PREPARING RETURN TO THEWILD: AN ASSESSMENT OF

PREPARING THE YUCATAN BLACK HOWLER MONKEY FOR ITS RETURN TO THEWILD: AN ASSESSMENT OF WILDTRACK’S APPROACH TO REHABILITATION AND REINTRODUCTION__________________________________A ThesisPresented toThe Graduate FacultyCentral Washington University___________________________________In Partial Fulfillmentof the Requirements for the DegreeMaster of ArtsPrimate Behavior ; Ecology___________________________________byBlanca Ponce-ValdezMay 2017ABSTRACTPREPARING THE YUCATAN BLACK HOWLER MONKEY FOR ITS RETURN TO THEWILD: AN ASSESSMENT OF WILDTRACK’S APPROACH TO REHABILITATION AND REINTRODUCTIONbyBlanca Ponce-ValdezMay 2017Nearly half of non-human primates are in danger of extinction due to the negative impact of anthropogenic activities. Some of these activities include habitat encroachment, hunting for bush meat, and illegal capture for the pet trade. Among the species most negatively affected is the family Atelidae (Campbell et al., 2011). For this reason, non-human primates remain a central focus in global conservation efforts.

Some of these efforts include welfare-based rehabilitation, re-introduction, and habitat preservation (Guy et al., 2014). Re-introduction projects have contributed significantly to conservation efforts, improved the lives of individual organism, promoted community education, and conservation values (Baker, 2002). However, Seddon et al.

(2007) reveals that often, very little development and post-release monitoring goes into poorly run projects and many fail to establish viable populations (Griffith et al. 1989; Wolf et al. 1996). Re-introduction projects can include animals from diverse backgrounds, including individuals removed from the wild, zoo-raised animals, or animals that have been confiscated from the illegal pet trade (Guy et al.

, 2014). Because many of these animals’ behaviors have been influenced by humans, many lack the social, behavioral, and ecological knowledge to survive in the wild and therefore must undergo an extensive rehabilitation process to ensure that individuals develop the appropriate behaviors necessary for their survival in the wild prior to being reintroduced (Cheyne et al., 2008). These behaviors include critical skills such as group formation, foraging abilities, response to predators, little to no human dependency, and behaviors like their wild conspecific’s (Guy et al., 2014).

Nonetheless, although methods used to achieve positive release outcomes exist, they are rarely reported in the literature (Guy et al., 2014), resulting in a major gap in the primate literature (Schwartz et al., 2016). In this study, I will assess the approach to rehabilitation and release of black howler monkeys (Alouatta pigra) at Wildtracks, Belize. The following organization has had a successful rehabilitation program in place for ten years, demonstrating 95% post-release survival rates (P.

Walker, personal communication, November 15, 2016). In this study, I will attempt to bridge the gap between pre-release training methods and rehabilitation outcomes through the identification and dissemination of information related to rehabilitation practices that result in positive release outcomes (IUCN/SSC, 2013).INTRODUCTIONNearly half of non-human primates are in danger of extinction. According to the International Union for Conservation of Nature Species Survival Commission’s (IUCN/SSC) Primate Specialist Group (2008), “48% of non-human primates are vulnerable, endangered, or critically endangered” (as cited in Guy et al., 2014). Of this 48%, 40% are Neotropical primates (Mittermeier et al.

, 2009). Among the species most negatively affected by the impacts of anthropogenic activities is the family Atelidae (Howler mMonkeys, Spider mMonkeys, Woolly mMonkeys, and Muriquis; ) (Campbell et al., 2011). Monkeys are also highly desired by humans as pets; , subsequently, there has been an intensification of illegally kept captive individuals (Cowlishaw ; Dunbar, 2000; Dietz et al., 1994; Harrington, 2015). For this reason, non-human primates remain a central focus in global conservation efforts. Some of these efforts include welfare-based rehabilitation, re-introduction, and habitat preservation (Guy et al.

, 2014).Re-introduction projects involving rehabilitated animals have offered many captive animals individuals a better quality of life (Kleiman et al., 1986) and contributed to the preservation of our wildlife biodiversity through the re-establishment of viable populations of threatened species (Tutin et al.

, 2001). However, re-introduction goals also present complications for rehabilitation programs and the animals being re-introduced (Cheyne et al., 2008), especially when the animals have become accustomed to a captive lifestyle (Baker, 2002, Guy et al., 2014). According to Fischer and Lindenmayer (2000) and Jule et al.

(2008), Ccaptive raised animals (13%) are less likely to demonstrate positive release outcomes compared to translocated wild animals (31%) (According to Fischer and; Lindenmayer, (2000); and Jule et al., (2008), as cited by Schwartz et al., 2016, p. 261). Rehabilitation is particularly challenging for animals that live in cohesive groups.

Group living animals typically learn survival skills (e.g. e.g., foraging, predator recognition, social, and reproductive behavior) from watching their parents or conspecifics (Cheyne et al.

, 2007; Schwartz et al., 2016). In addition, species that spend a significant amount of time learning essential subsistence strategies from their parents, demonstrate higher costs and spend more time in rehabilitation than other species (Cheyne, 2009). Animals raised in captivity that have not had the opportunity to grow with their natal group lack socially learned knowledge and therefore the skills necessary to survive in the wild (Cheyne, 2009).

For example, in a comparative study of captive raised lion tamarins and their wild born offspring, captive raised lion tamarins re-introduced to the wild showedindicated deficienciesy in foraging and locomotor skills in the re-introduced parents, while theirbut not their offspring demonstrated proficiency (Stoinski et al., 2003). In addition, the parents were more likely to come down to the ground, than their wild born offspring (Stoinski et al., 2003).Further challenges are presented in rehabilitation programs when the rehabilitants being considered for reintroduction are orphaned infants whose of species that forms strong familial or mother-infant bonds (Schwartz et al., 2016).

According to Cheyne (2009), Mmother-infant social bonds play a key role in the development of infants, and. fFor this reason, when infants often suffer negative stress when they are removed from their mothers at an early age, they often suffer negative stress (Cheyne, 2009; Schwartz et al., 2016). According to Schwartz et al. (2016) Pprimates deprived of species-specific social interactions often suffer developmental delays and display stereotypic behaviors (e.g.

e.g., pacing, over-grooming, coprophagy) (Cheyne 2006; Fritz ; Fritz 1978; Nash et al. 1999, According to Schwartz et al.

, (2016)). Yeager (1997) reveals that Tthe subsequent release of inadequately socialized individuals demonstrating developmental abnormalities will inevitably fail (Yeager 1997, as cited by Schwartz et al., 2016). For this reason, it may be most beneficial to encourage rehabilitants to form strong cohesive groups that can later be released together. In this way, inexperienced animals can take advantage of the benefits provided by group living.

According to Schwartz et al. (2016), some of these benefits includinge: more higher numbers of individuals to warn against predators, greater increased identification of palatable food resources, and increased access to mates (Hamilton, 1971; Krebs et al., 1972; Wrangham, 1980; Whitehead, 1986). Studies reveal that rehabilitating and releasing individuals in groups has improved reintroduction outcomes in many different animals (Shier, 2006; Cheyne, 2009). For example, Shier (2006) found that black-tailed prairie dogs (Cynomys ludovicianus) translocated with their families to beare five times more likely to survive and be reproductively successful than those translocated without families (Shier 2006).

Similarly, In addition, Schwartz et al. (2016) found that jjuvenile mantled howlers (Alouatta palliata) undergoing pre-release training in groups spent less time approaching humans and increased their time in the canopy (Schwartz et al., 2016). Nonetheless, although methods used to achieve positive release outcomes exist, they are rarely reported in the literature (Guy et al., 2014), thus resulting in a major gap in the primate literature (Schwartz et al., 2016). In this study, I will assess the approach to the rehabilitation and release of black howler monkeys (Alouatta pigra) at Wildtracks, Belize.

Wildtracks houses monkeys confiscated by the National Forest Department, rehabilitates them, and prepares them for release into the wild. Thise following organization has had a successful rehabilitation program in place for ten years, demonstrating 95% post-release survival rates (P. Walker, personal communication, November 15, 2016).

In this study, I will attempt to bridge the gap between pre-release training methods and rehabilitation outcomes through the identification and dissemination of information related to rehabilitation practices that result in positive release outcomes (IUCN/SSC, 2013). LITERATURE REVIEWAlouatta pigra: Recognition as a Species and Taxonomic History Alouatta spp. are among the most well studied (Gavazzi et al., 2008; Pavelka ; Knopff, 2004) and most widespread of all the Neotropical primates (Crockett ; Eisenberg, 1987). According to Cortés-Ortiz et al. (2015), Alouatta spp. can be found occupying ranges “from southern Veracruz State in Mexico to northern Argentina” (According to Cortés-Ortiz et al.

, (2015,), p. 56). The genus Alouatta has received special attention from ecologists and ethologists due to their seed dispersal abilities, sedentary lifestyle and colonial habitats, as well as their unique morphological characteristics (large bodies and loud vocalizations) (Estrada ; Coates, 1991; Smith, 1970).

However, most of what is known about howler monkeys is derived from studies of two howler species: the Central American mantled howler (Alouatta palliata) and the South American red (Alouatta seniculus) (Gavazzi et al., 2008). Meanwhile, little was is known about A. pigra (Pavelka ; Knopff, 2004).

Although the genus Alouatta has received a lot of attention in the scientific literature, relatively little is known about their taxonomy, and the recognition of individual species remains a topic of debate. For example, for many years, Alouatta A. pigra (as well as all Mesoamerican howlers) was considered a subspecies of A. palliata (Gray, 1845; Cortés-Ortiz et al., 2015).

It was not until Smith (1970) analyzed the morphological features (e.g. e.g., cranium, dentition, and hair) of two howler populations living sympatrically in Tabasco, Mexico, that Smith confirmed that A.

palliata and A. pigra were indeed two distinct species (as cited by Cortés-Ortiz et al., 2015). Horwich (1983) further supported the separation of A. palliata and A. pigra after noting morphological variances in male genitalia and group size.

According to Horwich (1983), Tthe testes of A. pigra males descend just aboutalmost entirely at the age ofduring infancy (Horwich 1983). In contrast, the testes of A.

palliata do not descend until they have reached sub-adulthood (Cortés-Ortiz et al.; 2015) (30-48 months) (Glander, 1980). Moreover, the Whitehead (1995) remarked on the differences in vocal patterns of the two species are different (Whitehead 1995). The separation of the two howler populations, A. palliata and A. pigra, was further reinforced by the identification of chromosomal differences and variances of thein male sex determinants. According to Cortés-Ortiz et al.

(2015), A. palliata exhibits 2n=54 chromosomes and A. pigra exhibits 2n=58. Moreover, in A. palliata, the sex of males is determined by the X1, X2, and Y sex chromosomes, whereaswhile in A.

pigra it is determined by the X1, X2, Y1, Y2 sex chromosomes (Cortés-Ortiz et al., 2003; Steinberg, 2008). Sequencing of mitochondrial DNA solidified the separation of the two species by revealing that they both belonged to two monophyletic groups, separating 3 MA, elevating A. pigra to species status (Cortés-Ortiz et al., 2003, 2015). According to Cortés-Ortiz et al.

(2015), Ccurrently there are nine confirmed species of howlers, including: A. palliata, A. pigra, A. seniculus, A. arctoidea, A. sara, A. macconnelli, A.

guariba, A. belzebul, A. caraya (According to Cortés-Ortiz et al., (2015),. However, there are three other taxa that are believed to be distinct species, but taxonomists are hesitant to elevate A. nigerrima, A.

ululataululate, and A. discolor to species status (Cortés-Ortiz et al., 2015, p. 55).

Further analysis of their genetic makeup is essential to confirm their species status (Cortés-Ortiz et al., 2015). As further genetic and morphological studies of howlers increase during the next few years, we expect the taxonomic arrangement proposed by Cortez et al. (2015) to change significantly.Alouatta pigra: Geographic Distribution, Ecology, and Conservation StatusHabitatThe black howler monkey (A. pigra), also known as “baboon” in Creole or “Saraguate” in Spanish, is one of the largest monkeys found throughout the Americas (Horwich ; Lyon, 1990).

Alouatta pigra occurs naturally in the Mesoamerican region, with a distribution limited to parts of the southern Yucatan Peninsula of Mexico, western Guatemala, and Belize (Baumgarten ; Williamson, 2007). H In Belize, the “baboon” is most common along the Belize River, demonstrating a preference for low-lying tropical rainforest under 1000 ft. (300 m) above sea level, but can also be found in the foothills of the Mayan mountains (Horwich ; Lyon, 1990). owever, gGroups primarily remain high in treetops along the river banks of “…terra firma rainforests, riparian forest, seasonally flooded riparian areas, and swamp areas, but can also be found in primary and secondary forests” (Marsh et al., 2008; Baumgarten ; Williamson, 2007). However, in areas lacking an appropriate habitat, howlers can be found living near urban areas in unsuitable habitats (Cuarón 1991, 1997; Marsh, 1999, 2001, 2002).

They are extremely flexible in their behavior and diet allowing them to adapt well to changing environments and the ability to inhabit a variety of habitats (Marsh et al., 2008; Horwich ; Lyon, 1990). They are highly arboreal, spending most of their time in treetops and seldom returning to the ground (Horwich ; Lyon, 1990).

According to Horwich and Lyon (1990), Iin Belize, the “baboon” is most common along the Belize River, demonstrating a preference for low-lying tropical rainforest under 1000 ft. (300 m) above sea level, but can also be found in the foothills of the Mayan mountains (Horwich ; Lyon, 1990). Home Range, Territoriality, and Group SizeThe home range of A.

pigra varies depending on troop size and availability of resources, but typically they inhabit small overlapping home ranges (Neville et al., 1988) between 3 to 25 acres (Horwich ; Lyon, 1990). For this reason, A. pigra is not considered strictly territorial, but there is no consensus on the territoriality of all species of Alouatta (Cornick ; Markowitz, 2002).

According to Horwich ; Lyon (1990), Tthe average territory size of A. pigra at the Community Baboon Sanctuary in Belize, is approximately 12-15 acres (Horwich ; Lyon, 1990). Although, A. pigra is not considered strictly territorial, but there is no consensus on the territoriality of Alouatta (Cornick ; Markowitz, 2002). In fact, at Bermuda Landing, Belize, Horwich and Gebhard (1983) found that A. pigra demonstrated territoriality (Horwich ; Gebhard, 1983).

It appears that they have established territories that they occupy year-round, and like many other primate species, they do not tolerate other groups in their immediate area (Horwich ; Lyon, 1990; Carpenter, 1965). It is believed that t is believed that howlers defend their territories from intruding troops by using their a set of loud vocalizations (Horwich ; Gebhard, 1983; Horwich ; Lyon, 1990). Because these howls are mostly performed at dusk and dawn, it is believed that they are utilized by howlers to promote spatial awareness and serve as a method to avoid conflict over resources or females (Kitchen et al., 2004; Horwich ; Lyon, 1990).

However, these calls can also be heard before it rains and when other animals are feeding, suggesting that spatial recognition may not be the chief function of howling behavior (Horwich ; Lyon, 1990). Alouatta. pigra lives in small groups that range on average from two to ten individuals with no groups exceeding ten (Horwich ; Lyon, 1990). These numbers are small compared to the numbers of A. palliata, whose groups can range from 2-45 individuals (Crockett ; Eisenberg, 1986). Troops are typically polygynous, meaning troops they generally have a single male living with multiple females and their young (Campbell et al.

, 2011). However, multi-male groups and solitary males living without a troop have been documented in the wild (Horwich ; Lyon, 1990). Howler troops remain stable from year to year and typically feed, sleep, and travel together. Occasionally, the troop will split up to feed, but later reform into the original troop (Horwich ; Lyon, 1990). Based on what we know about howler group structure,; group cohesion may be the key factor connected to the survival of A.

pigra. MorphologyHowler monkeys are one of the largest primate species inhabiting the Neotropics (Horwich ; Lyon, 1990). Males (A. pigra) typically weigh an average of 11.47-8 kg, while females average 6.

4 5-6 kg. On its own, the length of the body can be between 5245 and 7164 cm (Wildtracks, 1999; Fleagle, 1999). In addition, like similar to spider monkeys, A.

pigra possess a prehensile tail that is slightly longer than its body, averaging between 50 and 673 cm (20 and 24 in) (Richardson, 2006Wildtracks, 1999). The prehensile tail serves as another limb that allows howlers to hang from their tails and is used to grab onto branches, facilitating travel through the canopy, apy, and enabling them to harvest hard to reach food items (Campbell et al., 2007(Marsh et al., 2008; Milton, 1980). VocalizationsOne of the most unique characteristics of howler monkeys is their ability to produce one of the most powerful vocalizations in the Neotropics (Cortez et al. 2015) that can be heard from a mile away (Horwich and Lyon, 1990). These calls are produced using an elaborate set of throat structures, consisting of a pneumatized hyoid bone with a large hollow basihyal that serves as a resonating chamber (as cited by Cortez et al.

, 2015). Every howler species that has been studied exhibits two forms of loud calls: barks and roars (Altmann, 1959). In addition, Cortez et al. (2015) describes incipient forms of roaring and barking that are often observed at short range.

Consequently, they’re not classified as loud calls, but are typically produced during long calling bouts (Cortez et al., 2015). The incipient form of roaring generally consists of short pulses that resemble a brusque popping noise (Altmann, 1959).

In A. pigra, these incipient roars are not as common as in south American howlers and consist of short burst of popping (described as an ‘aw’ or ‘er’ sound) (Baldwin and Baldwin, 1976) that are often emitted before a full roar. Another call emitted prior to a full roar in A. pigra, is the incipient bark. The incipient bark has been described in A. palliata as an “unf unf unf” and a grunting sound in A. pigra (Kitchen DM unpubl.

data; Kitchen pers. Obs.; as cited by Cortez et al., 2015). On the other hand, a full roar is characterized by a high amplitude with a sound pressure level up to 90dB at a 5 m distance (Whitehead, 1995). Other common features of a howler’s roar are its low frequency and harshness (Cortez, et al.

2015). However, these calls can vary between species. For example, while many south American species emit full long roars with a long exhalatory and a short inhalatory phase, central American species (A. palliata and A. pigra) only emit short continuous roars with one long exhalatory emission that typically lasts 2.2 seconds (that is at times preceded by a short inhalation), followed by a short low amplitude call (as cited by Cortez et al., 2015).

Aside from loud calls, howlers also contain a vast repertoire of soft calls that are often neglected in the literature and continue to be understudied. Hence, most of the information on these vocalization is limited to studies on A. palliataand A. caraya. Soft calls discussed in the literature include: contact calls, immature calls, and alarm calls. Contact calls are produced when group members wander too far from their group.

These calls have been described as whimpers in A. palliata (Baldwin and Baldwin, 1976), cries (Calegaro-Marques and Bicca-Marques, 1997), and moo calls in A. caraya (Cunha and Byrne, 2013). All three calls have been observed in group progressions and stressful situations where the caller was observed away from the group. The moo call has been described as being representative of a true call and answer system in A. caraya(Byrne 2000; da Cunha and Byrne 2009) and is therefore thought to play a particularly important role in contact. However, further research is needed to fully understand the function of low amplitude calls in howlers (Cortez et al., 2015).One of the most unique characteristics of howler monkeys is their ability to produce one of the most powerful vocalizations in the Neotropics (Cortez et al. 2015). The call can be heard from miles away and has been described by Horwich and Lyon (1990), as being as loud as the call of a jaguar (Horwich ; Lyon, 1990). Howlers can produce these loud vocalizations using an elaborate set of throat structures, consisting of an enlarged hyoid bone placed near the vocal chords that serve as a resonating chamber. According to Horwich ; Lyon (1990), Hhowlers produce this sound by “narrowing their throat region around their relaxed vocal chords, increasing the pressure of the expulsed air, and extending the chambers in the hyoid cartilage, which funnel the sound into the large hyoid bone.” (Horwich ; Lyon, 1990). These elaborate throat structures have been found to beare much more developed in males who engage in most of this roaring behavior (Kitchen et al., 2004; Horwich ; Lyon, 1990). However, females will also join in, but produce higher pitched calls (Horwich ; Lyon, 1990).DietHowlers are assumed to be the most folivorous of all Neotropical primate communities (Eisenberg et al. 1972; Milton 1980) due to their dependence on leaves (Milton ; McBee, 1983) and dental morphology. Howlers have molars with large shearing crests that reveal an adaptation for chewing leaves (Marsh et al., 2008). However, recent studies of the feeding ecology of A. pigra revealed that black howlers balance their diet by eating a variety of foods, and their diet is dependent on the availability of those preferred foods (Pavelka ; Knopff, 2004). In addition, A. pigra is one of the only New World monkeys that includes mature leaves in its diet. Their dietary flexibility allows them to survive for extended periods of time on a strict leaf-based diet if leaves are all they have access to (Horwich ; Lyon, 1990). This may explain their ability to inhabit a variety of habitats. However, mature leaves are clearly not their first choice. A. pigra prefers to eat a variety of flowers, fruits, petioles, seeds, moss, stems, twigs, termites (when available), and young new leaves, with lower concentrations of toxic tannins and alkaloids (Emmons et al., 1996; Silver et al., 1998, 2000; Ostro et al., 1999), that are less fibrous, thus making them easier to digest (Milton, 1979). In Belize, they A. pigra demonstrates a preference for species such as bri-bri, fig and ramon (breadnut) (Wildtracks, 1999). Black howler monkeys at the Community Baboon Sanctuary in Belize have been best described as “as frugivorous as possible and folivorous as necessary” by Silver et al. (1998) (as cited by Pavelka ; Knopff, 2004, p. 106). Howlers consume young and mature leaves year-round, however, their consumption of fruit is dependent on its abundance (Silver et al., 1998). Studies reveal that theThe feeding ecology of A. pigra demonstrates that theyallows them tocan inhabit a variety of different habitat types. Their dietary flexibility facilitates the colonization of new habitats, either naturally or through a human-led process (Silver et al., 1998), hence, making them perfect good candidates for rehabilitation and reintroduction programs.Activity Behaviorally, the activity budget of A. pigra follows the typical Alouatta pattern (Pavelka ; Knopff, 2004). Howler monkeys are known for being large, energy-minimizing leaf-eating monkeys, spending up to 70% of their time resting high in the tree tops, fermenting leaves in their large caecum (Horwich ; Lyon, 1990; Marsh et al., 2008). Indeed, Rresting accounts for most of their daily activity, followed by feeding, locomotion, and social interactions (grooming and play) (Silver et al., 1998; Estrada et al., 1999; Pinto et al., 2003). Howler’s long elongated resting behavior is often correlated to their folivorous diet. Their energy minimizing lifestyle is thought to be a response to their consumption of low-quality leaves (Milton, 1980) that require extended periods of digestion and fermentation (Horwich & Lyon, 1990). However, other studies challenge this notion. Pavelka and Knopff (2004) found that A. pigra maintains this sedentary lifestyle even during times of high fruit availability, suggesting that, in this species, diet is much more generalized whereas behavior isn’t, indicating some form of phylogenetic constraint. “diet is much more ?exible and varied than is behavior and that activity levels may be more phylogenetically constrained.” On the other hand, playing and grooming form a minimal part of a howler’s daily activity (Horwich & Lyon, 1990). Social BehaviorHowler troops are maintained using a combination of friendly and aggressive behaviors directed between and within troops (Horwich & Lyon, 1990). Nonetheless, affiliative behavior is rarely observed in the genus Alouatta, as a result, social relationships are as being weak (as cited by Campbell et al., 2007). Grooming is rarely observed in howlers despite it being a typical behavior of many primate species to maintain social bonds. When it is observed, it is usually conducted in a relaxed situation between individuals of the opposite sex males and females that know each other well (Horwich & Lyon, 1990). Play is common among young howlers. However, adults will also chase and wrestle each other and display play faces (open mouth with their teeth showing), while making low-pitched play grunts. According to Horwich and Lyon (1990), Ssub-adult males elicit play from adult males as a strategy to extend their stay within the troop and avoid being forced, by the dominant male, to disperse (Horwich & Lyon, 1990). Play behavior is a common phenomenon among mammals (Oliveira et al., 2003) and has been widely documented in every primate species studied (Burghardt, 2005). Nonetheless, play and its functions have not been well defined in the literature (Bekoff, 1997). Many authors have defined play as behavior without a clear function, while others characterize it as being voluntary, spontaneous, pleasurable, intentional, and exaggerated (Bekoff, 1997; Burghardt, 2005). In respect to the functionality of play, it has been proposed that play may serve diverse functions (e.g. improving motor and cognitive skills) for individuals of different species, sex, and age (Bekoff, 1997) and may play a critical role in the development and socialization of young animals (Baldwin and Baldwin, 1978). Play may provide young animals many social skills (e.g. sexual behavior, predator avoidance, maternal behavior, controlled aggression) that may be useful to the individual, later in life. Play is common in young howlers. Often times, young howlers can be observed playing with themselves (feet, hands, tail) or with surrounding objects (leaves, twigs, fruit), but the most common form of play involves two or more individuals (wrestling, chasing) (Carpenter, 1934). In A. pigra, younger individuals typically chase and wrestle each other and display play faces (open mouth with their teeth showing), while making low-pitched play grunts. However, this phenomenon is not restricted to young monkeys, adults will also wrestle and chase each other. Young sub adult males have also been observed eliciting play from the dominant male as a strategy to extend their stay within the troop and avoid being forced, by the dominant male, to disperse (Horwich and Lyon, 1990). Nonetheless, in general, as individuals get older, play becomes more aggressive, and begins to resemble more serious physical aggression. Hence, as individuals mature, play is less frequent (Carpenter, 1934). Like many ungulate species, A. palliata and A. pigra males have been observed engaging in exploratory behavior toward female’s in estrus. These exploratory behaviors include: smelling the female’s genitalia, urine, or vaginal discharge (Carpenter, 1934, Horwich, 1983). Another sexual behavior that appears to play an important role in signaling copulation, is prolonged eye contact followed by rhythmic tonguing. This behavior appears specifically important to the female. Typically, a female will gaze at the male for a period of time and flick her tongue in a slow, but repetitive motion toward the male. However, rhythmic tonguing is not limited to females, these lingual gestures can be produced by either sex to signal copulation (Horwich and Lyon, 1990; Horwich, 1983; Carpenter, 1934). When threatened, adult males exhibit aggressive behaviors which serves as a warning to their aggressors. Some of these behaviors include: howling, piloerection, raised and hunched shoulders, branch grasping, and scent marking (Horwich and Lyon, 1990). For example, when an intruding troops impose on another group’s territory, resident groups roar and chase the intruders back to their own territories. These confrontations are often followed by roaring bouts between the two groups. Like other animals, when threatened, howlers will also raise their hair to make them look bigger and more intimidating. The latter, is typically followed by a behavior that consists of raising and hunching the shoulders, leaning frontward and grasping a tree branch. Male howlers also convey an angry message to other males using a gland on their throat region that leaves a scent after the male has rubbed his chest and throat on an object (Horwich ; Lyon, 1990). Black Howler Population in Belize ; Conservation StatusIn many areas of its range, the black howler monkey is rare and at risk of extinction (Horwich ; Lyon, 1990). However, Belize , however, is fortunate enough to have a healthy population of A. pigra, despite experiencing four catastrophic population crashes after devastating hurricanes swept through Bermudian Landing, Belize in 1931, 1954, and 1978 (Hartshorn, 1984; Bolin, 1981). In 1971, A. pigra faced another significant decline in its population after a devastating yellow fever epidemic nearly wiped out the entire Central American howler population (Baldwin, 1976; Hartshorn, 1984). Together, the four events nearly wiped outextirpated local howler populations, reducing them to significantly low levels and changing the behavioral dynamics of the remaining troops (Baldwin, 1976; Bolin, 1981). However, howler populations recovered rapidly (James et al., 1997) and in some areas “population densities of up to 250 individuals per km2 have been recorded” (Horwich ; Lyon, 1990), demonstrating the resiliency of this species. Nonetheless, high population densities of A. pigra are generally found in protected areas (Marsh et al., 2008). Unfortunately, A. pigra is listed as “endangered” under the IUCN Red List and is expected to experience a 60% decline over the next three generations (30 years) due to rapid rates of habitat decline, hunting for bush meat, and the pet trade (IUCN/SSC Primate Specialist Group, 2008). Young howlers are especially vulnerable to the illegal pet trade, as infants make appealing pets (Duarte-Quiroga ; Estrada, 2003). Generally, howler monkeys can adapt well to fragmented environments (Pavelka ; Knopff, 2004), and. thTheir generalized diets allow them to eat a variety of foods and their inactive lifestyles do not require large home ranges (Horwich ; Lyon, 1990). However, rapid rates of deforestation poses a major threat to howler populations. In fact, habitat disturbance is the major cause of decline (Marsh et al., 2008). Nonetheless, mMuch of the rainforest A. pigra inhabits has been cleared for agriculture and logging (Horwich ; Lyon, 1990). Among the most affected is Guatemala, with only 26% of its forest cover remaining, followed by Mexico (28%), and then Belize (59%) (Van Belle ; Estrada, 2006). For this reason, habitat fragmentation is a major focus in primate conservation due to its increased pressure on individual species and communities. Many conservationists are working together with local communities to develop conservation strategies to prevent the destruction of our tropical rainforests and preserve the biodiversity of wild populations. One of these conservation strategies is species re-introduction (Baker, 2002).Defining Welfare Based Primate Rehabilitation and Reintroduction for Conservation Re-introduction:The IUCN de?nes re-introduction as the “release of a taxon in an area from which it has been extirpated or become extinct” (Baker 2002). According to Kleiman (1989) humans have been reintroducing animals since the early 1900s, and although there is no clear documentation of the very first re-introduction, one of the earliest accounts has been traced back to 1907, when 15 American bison (Bison bison) were released into a reserve in Oklahoma (as cited by Seddon et al., 2007). However, the 1970s and the 1980s led to an increase in recognition and helped solidify species re-introduction as a conservation strategy, with the re-introduction of the “Arabian oryx (Oryx leucoryx), golden lion tamarins (Leontopithecus rosalia), and peregrine falcons (Falco peregrinus)” (Seddon et al., 2007, p. 304). Re-introduction projects have contributed significantly to conservation efforts, improved the lives of individual organisms, promoted community education, and conservation values (Baker, 2002). However, Seddon et al. (2007) reveals that often, very little development and or post-release monitoring goes is performed, particularly into poorly run projects, and many fail to establish viable populations (Griffith et al. 1989; Wolf et al. 1996), demonstrating and have high post-release mortality (Baker, 2002; Seddon et al., 2007). For example, a review on animal reintroductions conducted by Fischer and Lindenmayer (2000), “found that only 26% of the 116 projects assessed were deemed successful, failed re-introduction projects accounted for 27% failed, with the remaining 47% having unknown outcomes (Fischer & Lindenmayer, 2000 as cited by Guy et al. 2014, p. 140). Re-introduction projects can pose negative threats to wild populations and their natural ecosystem (Baker, 2002). For example, reintroduced animals habituated to humans can transmit diseases to wild populations if medical screening is not conducted prior to release. Such a problem arose with the reintroduction of hand-raised orangutans (Pongo pygmaeus) that were infected with tuberculosis (Mycobacterium tuberculosis) into an area with uninfected conspecifics (Jones, 1982). Regardless, wildlife restoration projects continued to increase globally (Seddon et al., 2007). As a result, the World Conservation Union’s (IUCN) Species Survival Commission formed the Reintroduction Specialist Group (RSG) (Seddon et al., 2007; Stanley Price & Soorae, 2003). In 1992, the RSG launched their first workshop leading to the formulation of reintroduction guidelines (Seddon et al., 2007). These guidelines were meant to serve as a guide to ensure that practitioners were utilizing a “best practice model or ideal code of conduct” when re-introducing wild animals (Baker, 2002). However, many continue to question the potential of species re-introduction as a conservation strategy, as it is believed that many of its practitioners fail to implement the IUCN guidelines into their projects. For example, a most recent review on welfare-based rehabilitation and reintroductions, found that of the “26 factors listed as being critical for rehabilitation and re-introduction (Table 1), only ten were implemented in less than 50 % of primate rehabilitation projects” (Guy et al., 2014, p. 142). Table 1. ‘Rehabilitation Stages IUCN Guideandlines and Pprocedures other crucial factors Cconsidered tto be Ccritical for Rrehabilitation and Rre-introduction, Aadapted from Tthe IUCN Guidelines for Non-Human Primate Re-introductions’ (Baker, 2002; as listed by Guy et al., 2014, p. 142).Rehabilitation StagesRehabilitation StagesIUCN GuidelinesIUCN 26 FactorsArrivalArrivalQuarantine (>31 days)Clinical Examination (e.g. dentition, reproductive organs, previous injuries, ectoparasites, weight), etc.) Disease Screening (e.g. endoparasites, viruses, etc.)Vaccines (e.g. yellow fever, rabies, etc.)History collection (as possible)QuarantineMedical assessmentAssessmentGroup FormationHistory Collection (as possible)Genetics (Geographic Origin)Socioecology and BehaviorBehavioral assessmentGeneticBehaviorCompatibilityWild group size and compositionTraining & PreparationRehabilitationReduce Human ContactFree of StereotypesNatural Enclosures Natural Enrichment Natural GroupingNatural BehaviorAssess release suitabilityConspeci?c re-socializationLimit human contactPredator awareness trainingNatural foodNatural enclosuresEnvironmental enrichmentPre-ReleasePre-release AssessmentHealth/Disease ScreeningAssess Suitability of Release Ssite (e.g. predators, habitat type, protective status, wild populations)Behavioral Assessment (e.g. foraging skills, human dependency, group stability)Further Reduce Human ContactObserve behavior and identify problemsHealth/disease screeningPre-releaseRelease Transport PlanSoft Release (acclimatization to new environment, supplemental food and water).Acclimatization to the release siteNatural food in pre-release enclosureFood provided in a way to develop foraging skillsFurther limit human contactPost-ReleaseReleaseLong Term Monitoring (>1 year)Periodic Assessment of Success and Success Criteria Soft releaseTransport planPost-releaseLong term monitoring (>1 year)Periodic assessment of success and success criteriaWelfare-Based RehabilitationRe-introduction projects can include animals fromspecies with diverse backgrounds, including individuals removed from the wild, zoo-raised animals, or animals that have been confiscated from the illegal pet trade (Guy et al., 2014). Others have been directly affected by human activities such as: clearing land for agriculture and hunting for the bush meat tradeOther animalss have been directly impacted by human activities such as “land clearing or hunting for the bush meat trade, resulting in many orphaned, injured, and illegally kept individuals” ((Yeager, 1997; Goossens et al., 2005; Wimberger et al., 2010). Because humans have influenced the behavior of many of these animals’ behaviors have been influenced by humans, , many lack the social, behavioral, and ecological knowledge to survive in the wild, and therefore must undergo an extensive rehabilitation process to ensure that individuals develop the appropriate behaviors necessary for their survival in the wild prior to being reintroduced (Cheyne et al., 2008). These behaviors include critical skills such as group formation, foraging abilities, response to predators, little to no human dependency, and a behavioral repertoire similar to s like their wild conspecifics (Guy et al., 2014). Even so, theThe rehabilitation and release of primates as a conservation strategy has not been well assessed in the primate literature (Guy et al., 2014). In fact, Tthe IUCN defines rescue and welfare rehabilitation as “the movement of wild primates from one area to another to rescue them from a hazardous situation or to resolve human-primate conflicts, or the release of captive primates, such as orphaned or surplus animals, to attempt to improve their welfare” (Baker 2002), but does not condone its use as a conservation strategy. For this reason, the IUCN does not specifically cover it under their guidelines or list it as a reintroduction or conservation approach because its main objective is “animal welfare” and not conservation (Baker, 2002; Guy, 2014). Nevertheless, the IUCN encourages rescue and rehabilitation programs to utilize the guidelines (Baker, 2002) as a framework for the assessment ofto assess rehabilitation programs (Guy et al., 2014). The IUCN iseven though they are not specific about what constitutes rescue and welfare rehabilitation (Baker 2002; Guy et al., 2014). Wildlife rehabilitation is defined more specifically in relation to animal welfare. T by the American National Wildlife Rehabilitation Association (NWRA) defines rehabilitation as “the treatment and temporary care of injured, diseased and displaced indigenous wildlife, and the subsequent return of healthy viable animals to appropriate habitats in the wild” (Atkinson, 1997, p. 355), and welfare is an individual’s . According to Broom (1988), “the welfare of an individual is its state as regards its attempt to cope with its environment” (Broom 1988, p. 6). For example, under stressful conditions, animals utilize a variety of coping methods to cope with such conditionsmechanisms. Animal welfare is typically defined in terms of natural living (e.g., an animal should be able to perform its natural behavior and live a natural life), an animal’s feelings (e.g. e.g., animals should be free from pain or stress), and an animal’s biological function (e.g. e.g., animal should not experience reduced fitness, diseases, injury) (Fraser et al., 1997). As more non-human primates find themselves displaced by negative man-madeanthropogenic influences, the need to formulate guidelines specific to the reintroduction of rehabilitated animals becomes more and more increasingly crucial. In addition, it is vital to disseminate any data related to welfare-based rehabilitation to address any issues that continue to plague these projects and to also ensure that they are improving the welfare of these individuals, as well asand promoting their long-term survival in the wild. Proposed Criteria for Assessing the Suitability of A. pigra for ReleaseAccording to the IUCN’s guidelines for reintroduction, “released animals should exhibit behaviors essential for their survival and reproduction, and for compatibility with conspecifics.” However, many ex-pets and rescued primates do not acquire the same skill level as their wild conspecifics (Cheyne, 2009). For this reason, it is crucial to perform an evaluation of individuals being re-introduced to assess their capacity to survive. Below, I have highlighted the important aspects of wild howler behavior that rehabilitated individuals must master prior to their release, which were used in this study to create an ethogram of howler behavior (Table 2). Table 2.Proposed Criteria for Assessing the Suitability of A. pigra for ReleaseBehaviorDescriptionActivityThe activity and dietary profiles of A. pigra in northern Belize is almost identical to that reported for other members of the genus in other areas (Silver et al., 1998). A. pigra in northern Belize spends 61.9% of its time inactive, 24.4% feeding, 9.8% locomoting, 2.3% engaged in social activities (playing and grooming), and 1.5% vocalizing. A similar dietary profile has been observed in southern Belize with a general level of inactivity at 66.33% followed by 18.57% spent feeding, 7.49% locomoting, and 3.6% spent socializing (Pavelka & Knopff, 2004, p. 107).Social BehaviorsPlay: Young howlers within a troop exhibit higher frequencies of play behavior. They will typically chase or wrestle each other, while giving low-pitched play grunts (Horwich & Lyon, 1990). Play behavior is important as it serves a key role in sensory, motor, social, and cognitive development (e.g., Fagen 1981, 1993; Spinka et al., 2001), which can be used later in life to “capture prey, avoid predators, ?ght with conspeci?cs, attract a mate, or in infant caretaking” (e.g., Fagen, 1981; Smith, 1982). Aggression: Howling: Howlers are infamous for their loud vocalizations that can be heard throughout the day when they hear loud noises, before it rains, and when others are feeding. They are most common at dawn and dusk (Horwich & Lyon, 1990).Aggressive threat: Adult males exhibit aggressive behaviors when threatened. They often exhibit piloerection, which serves as a warning to its aggressor. They then raise and hunch their shoulders, while quickly leaning forward and grasping a tree branch (Horwich & Lyon, 1990).Aggressive throat rubbing: Male howlers also convey an angry message to other males using a gland on their throat region that leaves a scent after the male has rubbed his chest and throat on an object (Horwich & Lyon, 1990). Grooming: Grooming behavior, a widespread practice in many monkeys to maintain group peace, is rarely documented in howlers. However, when it is observed, it typically occurs between a male and female in a relaxed situation (Horwich & Lyon, 1990). Copulation: Reproductive success will be determined by the presence of mating behavior (Van Belle & Bicca Marques, 2015; Horwich, 1983a).Foraging BehaviorThe inability to find food in natural environments poses a major problem for rehabilitation and release programs and is often associated with poor post-release survival rates (Britt et al. 1999; Cheyne 2009; Frantzen et al. 2001; Mills 1999). A survey response from rehabilitation centers associated with A. pigra, reported that they require assistance to recognize palatable foods (Guy et al., 2013). For this reason, it is important to evaluate the dietary profile of rehabilitated howlers prior to their release. The howler diet consists primarily of young leaves and fruit, with young leaf consumption averaging 37.2% and fruit averaging 40.8% of their monthly diet. However, mature leaves were consumed 7.9% of the time. On the other hand, flowers averaged 10.2% of their monthly feeding time, but flower consumption peaked during the dry season, making up 36.8% of their monthly feeding time (Silver et al., 1998).Height in canopy/observed on the groundWild howler monkeys are an arboreal primate species that lives high in the canopy of tropical rainforests. They generally avoid coming to the ground, but will occasionally descend to the ground to cross gaps between trees in highly fragmented forests (Pozo-Montuy & Serio-Silva, 2008). Nonetheless, arboreal species usually avoid being on the ground, as it poses an increased risk of predation. When released, it is important that howlers remain in the canopy and are not seen travelling near the ground.Observed Attracted to HumansAll howlers at the primate rehabilitation center have interacted with humans in some form during their time in captivity. As a result, many have become dependent on humans. Due to their dependence on humans during captivity, many of these primates demonstrate a low chance of surviving post-reintroduction. For this reason, it is important to provide A. pigra with semi-wild enclosures with limited human contact to ensure their independence from humans and enable their survival in the wild (Baker, 2002).LocomotionHowlers are highly arboreal, containing prehensile tails that serve as a fifth limb, to grasp branches and anchor the body during feeding time and locomotion (Marsh et al., 2008; Campbell et al., 2011).Group CohesionGroup cohesion is important for survival, territory defense, and raising successful offspring. Howlers feed, sleep, and travel together (Horwich & Lyon, 1990). For this reason, group cohesion is taken into consideration in this study and measured through proximity to conspecific.Wildtracks and the Primate Rehabilitation Program for A. pigraQuarantinePrimates that enter Wildtrack’s Primate Rehabilitation Center arrive at in various stagesconditions. Often, monkeys are brought in ill health, stressed, traumatized or behaviorally challenged. Many of these individuals that are rescued from the pet trade have been exposed to multiple pathogens and diseases due to inadequate husbandry and nutrition. Many times, pet monkeys share food and drinks consumed by their owners causing the exchange of zoonosiszoonoses. For this reason, when monkeys first arrive to the primate rehabilitation center, they are sent to quarantined where theyand are kept under close observation and screened for pathogens. This process usually lasts up to 30 days to reduce the risk of disease transmission to other monkeys at the center (P. Walker, personal communication, November 15, 2016).Stages of the rehabilitation process at Wildtracks:Monkeys at Wildtracks pass through four rehabilitation phases, depending on their age and species: nursery, forest cages, pre-release, and release.Stage One: NurseryThe nursery unit is where the youngest monkeys (ranging between one week to ten months of age) are housed after they have passed quarantine. During this time, young monkeys are given 24-hour care. Because many infants come in many distinct stagesmultiple conditions (traumatized, sick, injured, as young as a week old, or panicking because they have been separated from their mothers), they require intensive care, warmth and physical contact from trained personnel. Many times, babies require caregivers that can support and stimulate them until they have gained the confidence and skills to become part of a troop. Once these youngsters become comfortable in their pristine new environment, they are introduced to others of a comparable size and age and . Once they have formed a group, these young monkeys learn to work together as a troop (P. Walker, personal communication, November 15, 2016).Stage Two: Forest CagesMonkeys that demonstrate the confidence to be separated from the support of the nursery team are moved into large outdoor forest cages. The fForest cages are enriched with palm trees and bushes to help monkeys develop foraging and locomotion skills. In addition, contact with caregivers is substantially reduced to feeding times. During this time, the howlers are encouraged to develop group behavior and transfer their focus from their caregivers to operating as a social unit. The goals of this stage are to allow them to develop social bonds and learn to feed, move, and play as a group to enhance their chances of survival in the wild. Depending on several factors duringin their growth and development, the followingthis stage can be a quick or lengthy process with howlers spending between 6 to 12 months in this phase before being moved to the next stage of the rehabilitation process. Monkeys that came into the center as infants may spend a year or more in stage two (P. Walker, personal communication, November 15, 2016). Stage Three: Pre-releaseThe pPre-release stage is where howlers learn to perfect their coordination, locomotor, and communication skills required to facilitate movement throughout the rainforest canopy. In this stage, they are placed in extensive enclosures with ¾ acres of forest surrounded by electric fencing. During this time, they are still provided with supplemental food, but human and howler interaction is very limited. Throughout the process, they are monitored closely by caregivers to assess group cohesion, locomotor, and foraging skills before moving to the post-release stage in the Fireburn Reserve (P. Walker, personal communication, November 15, 2016).Stage Four: ReleaseThe subsequent release of howlers, between the ages of 2½-3 years, into the Fireburn Reserve usually occurs in June, which is categorized as a time of fruit abundance (P. Walker, personal communication, November 15, 2016; Cavada, 2012). The Fireburn Reserve provides a suitable site for the re-introduction of A. pigrablack howlers, meeting all guidelines listed by the IUCN/SSC Reintroduction Specialist Group (2002). For example, A. pigra is being re-introduced into an area within its historical home range (Fireburn Reserve) from which it became locally extinct (Baker, 2002), after populations were significantly decimated by devastating hurricanes and fatal yellow fever outbreaks (Hartshorn, 1984; Bolin, 1981; Baldwin, 1976). Moreover, the release of A. pigra the black howler into its former range contributes to the re-establishment of viable populations across the landscape. Studies conducted at the Fireburn Reserve to ensure that there were suitable areas for howler monkey releases, determined that the Fireburn Rreserve could sustain growing numbers of re-introduced populations (in terms of food abundance and canopy structure) (Fanigliulo, 2005). In addition, previous causes of the taxon’s decline are no longer present and hunting pressures have been identified and reduced to a safe level. The site currently exhibits low levels of hunting pressure, making it a suitable area for howler monkey releases (Wildtracks, 1999). Prior to the release of howlers to the Fireburn Reserve, howlers they undergo a soft-release where the monkeys are transported to the reserve in kennel crates (P. Walker, personal communication, November 15, 2016).This StudyWildtracks’ overall goal is to increase the viability of howler populations in Belize by working with the Forest Department to end the illegal primate trade in primates (a critical threat to primates throughout much of Central America) and by helping improve conservation planning to decrease habitat loss and fragmentation – a primary threat to the species. The aim of this study was to assess confiscated and rescued A. pigra black howler monkeys (Alouatta pigra) as they were rehabilitated for their reintroduction to the wild. Wildtracks’ overall goal is to increase the viability of howler populations in Belize by working with the Forest Department to end the illegal trade in primates (a critical threat to primates throughout much of Central America) and by helping improve conservation planning to decrease habitat loss and fragmentation – a primary threat to the species. The specific objectives of this study were the following: (1) identify what protocols and procedures are in place at Wildtracks for pre-release rehabilitation and post-release monitoring; (2) observe and record pre-and post-release behaviors to document the behavioral and social repertoires of individuals in each all stages of the rehabilitation process; (3) compare pre- and post-release behavior to that of wild conspecifics as reported in the primary literature; (4) formulate a set of recommendations (based on IUCN guidelines: Baker 2002; Beck et al., 2007) to further strengthen reintroduction protocols already in place at Wildtracks.’ Primate Rehabilitation Centre. Based on the information stated in the primate literature related to primate rehabilitation practices, I predicted that as time in rehabilitation increased:, (1) rehabilitants would demonstrate a decrease in observed stereotypic behaviors;, (2) an increase in naturalistic species-typical behaviors (e.g., social interactions);; (3) an increase in group cohesion, as (measured through proximity;), and (4) a reduction in behaviors associated with human dependency (e.g., approaching humans).METHODSThis StudyWildtracks’ overall goal is to increase the viability of howler populations in Belize by working with the Forest Department to end the illegal primate trade (a critical threat to primates throughout much of Central America) and by helping improve conservation planning to decrease habitat loss and fragmentation – a primary threat to the species. The aim of this study was to assess confiscated and rescued A. pigra as they were rehabilitated for reintroduction to the wild. The specific objectives of this study were the following: (1) identify what protocols and procedures are in place at Wildtracks for pre-release rehabilitation and post-release monitoring; (2) observe and record pre-and post-release behaviors to document the behavioral repertoires of individuals in each stage of the rehabilitation process; (3) compare pre- and post-release behavior to that of wild conspecifics as reported in the primary literature; (4) formulate a set of recommendations (based on IUCN guidelines: Baker 2002; Beck et al., 2007) to further strengthen reintroduction protocols already in place at Wildtracks.Based on the information stated in the primate literature related to primate rehabilitation practices, I predicted that as time in rehabilitation increased: (1) rehabilitants would demonstrate a decrease in observed stereotypic behaviors; (2) an increase in naturalistic species-typical behaviors (e.g., grooming, copulation, play); (3) an increase in group cohesion, as measured through proximity; and (4) a reduction in behaviors associated with human dependency (e.g., approaching humans).Identification of Protocols and Procedures To identify all protocols and procedures in place at Wildtracks, I created a checklist based on the guidelines listed by the IUCN (Guy et al., 2014) (Table 3), as these guidelines are considered “best practice” and deemed important to optimize successful rehabilitation and reintroduction. I then compared the two to determine how much of Wildtracks’ approach was adopted from the IUCN guidelines (because these guidelines are meant to maximize positive outcomes) and how much of the approach is taxon-specific for that region. The goal was to make this information accessible to other rehabilitation and re-introduction projects to ensure that they achieve their conservation goals with minimal side effects to the individuals being re-introduced. Table 3. Summary of Protocols in Place at Wildtracks in Comparison to IUCN Guidelines for Nonhuman Primate Re-introductions (Guy et al., 2014, p. 163-164). StagesWildtrack’s ProceduresArrivalQuarantine (>31 days) Clinical Examination (dentition, reproductive organs, previous injuries, ectoparasites, weight)Disease Screening (endoparasites, viruses)Vaccines (yellow fever, rabies) (MISSING)AssessmentHistory Collection (as possible)Genetics (Geographic Origin) (MISSING)Socioecology and BehaviorRehabilitationReduce Human ContactNatural EnclosuresNatural EnrichmentNatural GroupingNatural FoodPre-ReleaseHealth/Disease ScreeningAssess Suitability of Release Site (e.g. predators, habitat type, protective status, wild populations)Behavioral Assessment (e.g. foraging skills, human dependency, group stability)Further Reduce Human ContactReleaseTransport PlanSoft Release (acclimatization to new environment, supplemental food and water).Post-ReleaseLong Term Monitoring (>1 year)*Check marks indicate that procedures are in place, asterisks indicate that some procedures are missing, and no mark indicates that no protocols are in place.Protocols and Procedures in Place at Wildtracks for Pre-ReleaseArrival (Quarantine)Quarantine procedures are in place at Wildtracks. Upon arrival, every howler is placed in an 8’x8’x9′ ft. quarantine enclosure where they remain for a minimum of 30 days until they’re medically cleared by a veterinarian. However, veterinary visits were not observed. Arrival (Clinical Examination) The IUCN Guidelines for primate re-introduction recommend conducting a thorough clinical examination under general anaesthesia to ensure overall health and reduce the chance of spreading infectious disease. Nonetheless, a thorough clinical examination under anesthesia was not observed during my time at the rehabilitation center.Assessment (Disease Screening/Vaccines)Fecal samples are collected and tested for parasites (giardia, mange, roundworms, hookworms). Pyrantel is given to treat roundworms and hookworms. Serious cases of mange and giardia are assessed by a local veterinarian and treated with medication. However, vaccines are not given to howlers, as they’re not deemed necessary by the staff at Wildtracks. No other disease screening was observed at this time. Assessment (History Collection) Prior to arrival at the rehabilitation center, the staff at Wildtracks collects as much information (as possible) from the locals or authorities. Then, a physical assessment of the howler’s condition is performed. When assessing a howler’s condition, they look at their coat and weight for any obvious signs of ailments. A howler is considered to be in “good condition” if they demonstrate long, silky, dense black fur (Richardson, 2006; American Zoo, 2006) and are of the average weight for a male or female howler (Richardson, 2006). Poor condition is determined by poor fur and weight. If a howler appears to be seriously injured or highly emaciated, then veterinary care is provided. However, this is usually avoided due to lack of access to good veterinary care.Assessment (Genetics/ Geographical Origin)No genetic information exists for rehabilitants and geographic origin is difficult to determine without genetic information.Assessment (Socioecology and Behavior)Wildtracks does collect data on the ecology and behavior of this taxon, within its range. They are able to collect information year-round through their relationship with the University of Leeds, which offers graduate students grants to conduct research at Wildtracks (P. Walker, personal communication, November 15, 2016).Reduce Human ContactThe youngest monkeys (ranging between one week to ten months of age) are given 24-hour care from trained personnel. However, as they get older, their care is reduced to 8 hours. All other individuals in further stages of rehabilitation have human contact reduced to feeding times.Rehabilitation (Natural Enclosures & Environmental Enrichment)Young howlers in early stages of rehabilitation are provided with enrichment (ropes, swings, hammocks, kongs), lianas, and wooden structures to help them develop climbing skills. In the forest cage stage of rehabilitation, only natural wooden climbing structures, ropes, lianas, and hammocks are provided to promote more naturalistic movements across the enclosure. Pre-release enclosures are large patches of forest surrounded by electric fencing, containing trees similar to those found at their release site. However, within the enclosure they still contain a small cage where howlers can find fruit and water that is provided as a supplement by their caregiver. These enclosures do not contain enrichment and are arranged similar to their natural habitat with natural trees similar to the ones found at their release site. Pre- release enclosures are divided into three separate enclosures (pre-release one, two, and three). Pre-release one contains smaller trees than pre-release two. Pre-release two contains trees larger than pre-release one, but smaller than pre-release three. These enclosures are set up in this way to help newly introduced howlers adjust to new heights in the trees. Rehabilitation (Natural Groupings)Natural groupings exist for all individuals considered for release. For example, each group contained two or more individuals of the opposite sex or groups with all females. Rehabilitation (Natural Food)Howlers are not provided with a fully natural diet. They are fed a combination of fruit (watermelon, papaya, banana, mango, apples), not found in their natural habitat and leaf browse that does grow naturally at their release site. For example, species such as bri-bri and ramon are commonly given to encourage foraging skills. Young howlers and individuals below the average weight for a howler, are given Ensure as a replacement for milk and source of protein to help them regain their strength and obtain a healthy weight. Pre-release Assessment (Behavior and Foraging)Staff routinely assesses group cohesion, locomotor, and foraging skills before moving individuals to new stages in rehabilitation (P. Walker, personal communication, November 15, 2016). For example, young howlers that demonstrate group cohesion, confidence in their foraging abilities, and locomoter skills can be considered for the forest cage stage of rehabilitation. As you move further into the rehabilitation process there should be an increase in naturalistic behavior like the one listed in the proposed criteria for release. Volunteer caregivers are also encouraged to report any abnormal behavior in rehabilitants. However, these reports aren’t always consistent and dismissed if an individual is not familiar with natural primate behavior.Pre-release Assessment (Predators)No predator response training is in place at this moment. Pre-release Assessment (Health Check)In this case, a dose of pyrantel and anti-parasite medication based on individual weight was given to rehabilitants before being moved to the transport crate. Fecal examinations are conducted routinely to determine parasitic infection, but from my observations no pre-release health assessments exist, unless there are clear signs of physical ailments. No other health assessments were observed.Pre-release Assessment (Further Reduce Human Contact)During this time, they are still provided with supplemental food, but human and howler interaction is limited to feeding. Pre-release Assessment (Release site (Predators, Food & Water, Wild Conspecifics, Habitat Type, Protection Status))The suitability of the Fireburn Reserve as a release site was last assessed in 2005. The following study determined that the Fireburn Reserve could sustain growing numbers of re-introduced populations (in terms of food abundance and canopy structure) (Fanigliulo, 2005). However, no other assessments of the site have been conducted since then. The last population study was conducted by Fanny Tricone in 2015, but more recent population numbers are limited to tracker’s knowledge and difficult to determine (Tricone, 2018). Release (Release Transport Plan)Individuals were put into kennels and transported by boat to the reserve. After arrival, they were zip-tied to large bamboo sticks and carried by the volunteers to their release site, which was about a mile and a half from the drop off location. Release – Soft release (Acclimatize in Enclosure, Supplemental Food and Water))Soft release enclosures are similar to the quarantine enclosures and measure 8’x8’x9′ ft. Howlers remain in these enclosures for three days and continue to be provided with supplemental food and water. Volunteers and trackers are also encouraged to monitor their behavior and report any stress behaviors. However, from my observations, howlers that demonstrate stress behaviors may still be released.Post-Release (Monitor)Newly released individuals are monitored seven days a week for three months, then they transition to monitoring every other week for up to a year. During this time, trackers observe general behavior, inter-group interactions, group stability, health, and reproductive behavior. Research SiteThis research was carried outperformed in two different locations in northeast Belize, Central America. Pre-release observations of A. pigra were conducted at Wildtrack’s Primate Rehabilitation Center located in the northeast corner of Belize approximately two miles southeast of Sarteneja on the shore of Corozal Bay. Post-release observations were conducted at the Fireburn Reserve. The reserve is an 1818-acred area that is home to the Fireburn community and its surrounding farmland. It is also home to a variety of flora and fauna including 177 plant species, 36 species of mammals, 208 species of birds, and 65 species of reptiles and amphibians Together, Wildtracks and the Fireburn community manage the reserve located on the Eastern shore of Shipstern Lagoon in the Corozal District of northeastern Belize (18° 12′ 21.5994″ N, 88° 11′ 16.8″ W) (Figure 1) (Wildtracks, 2017).Figure 1. Map of Wildtrack’s’ protected areas in Belize and the location of the release sites. (Wildtracks, 2015).Study GroupOver the course of this study, behavioral observations were performed on 13 howlers housed at the rehabilitation center (Table 2), including four who were released in June 2017. Post-release observations were conducted on these four howlers, totaling two male-female pairs,. Pair one included one adult male (Balou-) and one adult female (Kat ). The second pair also included one male and (Darwin) and- one female (Sansa (F)) (Table 43). All howlers in this study were surrendered to Wildtracks or confiscated by authorities of the National Forest Department who brought them to the rehabilitation center. All howlers have undergoneunderwent an extensive rehabilitation process to ensure that they demonstrate the a similar behavioral repertoire like that ofto their wild conspecifics, which is necessary to for survivale in the wild. All individuals wereare considered “captive raised,” meaning they were wild born but spent time in captivity after their illegal capture (Cheyne, 2008).Table 42.Characteristics of howlers under studyStudy Ssubjects’ N demographics: name, Ssex, and Mmonths Sspent in Rrehabilitation, Age, Age Class, and Source.IndividualName Group Sex(M/F) Months in Rehabilitation Estimated Age Age Class SourceClifford N M 11 15.5 Juvenile WRoxy N F 13 17 Juvenile WPuck N M 4 9 Infant XPJade N F 4 10.8 Infant XPJo F1 M 25 61 Adult WBrea F1 F 14 50 Adult XPMolly F2 F 11 23 Sub adult WAnnie F2 F 23 29 Sub adult WAnerie F2 F 18 28 Sub adult XPKat PR F 34 43 Sub adult XPBalou PR M 20 38 Sub adult XPSansa PR F 33 51 Adult XPDarwin PR M 33 51 Adult XP*Source: W= Animals Born in the Wild, XP= Animals Kept as PetsData CollectionIn this study, individuals at each stage of rehabilitation were identified by group, sex, age, and source (Table 4). Age classes were divided into four groups: infant, juvenile, sub-adult, or adult (based on Clarke, 1990). I used Clarke (1990) to differentiate between the different groups. Individuals between 0-12 months were grouped into the infant category. Rehabilitants between 12-36 months were classified as juveniles. An individual between 30-48 months was considered sub-adult and adults were defined as being greater than 48 months. Age was calculated based on the estimated age at intake. Individuals were also identified based on their source of origin: captive, wild, pet, or rehabilitated. In this study, individuals in at each stage of rehabilitation were identified by group, sex, age, and source. Age classes were divided into four groups: adult, sub-adult, juvenile or infant. Age was calculated based on the estimated age at intake. Individuals were also identified based on their source of origin: captive, wild, pet, or rehabilitated. Observational data for the nursery, forest cage one, and forest cage two stages of rehabilitation was collected three days/week for four weeks between July 01, 2017 and July 31, 2017, resulting in 12 days of observations, divided into five observation periods. . Observational data for the post-release stage of rehabilitation was collected seven days/week for one week between June 12, 2017 and June 19, 2017, resulting in seven7 days of observations. Observations at the rehabilitation center began at 0700 and ended at 1700. Post-release observations began at 0500 and ended at 1900. Data was collected using two different observational methods: all occurrences sampling and scan sampling. All occurrences sampling was used during all stages of the rehabilitation process to record vocalizations and stereotypic behaviors (repetitive behaviors without a clear function; Mason, 1991) to provide a greater understanding of the variables that affect the length of the rehabilitation process and survival rates in the wild (e.g., rocking, pacing, self-mutilation (excessive grooming), bite caging, etc.). Data collection for the quarantine and pre-release stages of rehabilitation was not possible, as there were no individuals found during that time in those two stages at the time of the study. All occurrences sampling was used during all stages of the rehabilitation process to record the presence of vocalizations and stereotypic behaviors (repetitive behaviors without a clear function (Mason, 1991) that appeared noteworthy and could be used to hint at any social, affiliative, or aggressive behavior and provide a greater understanding of the different variables that affect the length of the rehabilitation process and survival rates in the wild (e.g., rocking, pacing, self-mutilation (excessive grooming), biting caging, etc.).For the following stages, the nursery unit, forest cages, and post-release stages, I performed used 30-second scan sampling intervals for one hour, with a 30-minute break for rest and relocation between every hour (see Table 5 for information on enclosures sampled). Scan sampling is particularly useful for observing social relationships (Altmann, 1974, Setchell ; Curtis, 2011). With every scan, I recorded social interactions, aggressive, affiliative, and feeding behavior, as well as documented their daily activities (e.g., time spent feeding, resting, locomoting, socializing, height in canopy, proximity, and interactions with humans) using an ethogram that I created of common howler behaviors found in the primate literature (Table 65). I then adjusted this ethogram during the course of this study to include observed behaviors not listed.Table 5. Enclosure Size Measured in Feet for Different Stages of RehabilitationEnclosureSize in ftGroupNursery Indoor Backroom7.5’x 7.7′ x 8’Cliff/Roxy/Puck/JadeNursery Indoor4’x4’x7Cliff/Roxy/Puck/JadeForest Cage Double Enclosure 120’x12’x11 (2)Jo/BreaForest Cage 216’x16’x9’Anie/Anerie/MollyTable 6.Ethogram of Social Interactions between A. pigraNon-Social BehaviorsDescriptionVocalizations (VO)Howls, loud, or quiet noises uttered from mouthAbnormal (AB)Pacing, rocking, cage-biting, over-grooming, self-mutilationResting (RE)Lying on the ground, surface, or human in an inactive and relaxed state.Locomoting (LO)Move from one area to another (one tree to another or one side of the enclosure to another side.Feeding-Drinking (FD)Consuming leaf browse, insects, fruit, or water.Observed on Ground (G)Sitting, playing, or locomoting on the forest floor or at the bottom of an enclosure.Proximity to Conspecific (P)a. 0-2 m apartb. 2.1-4 m apartc. 4.1-6 m apartc. 6.1-8 m apartc. 8.1-10 m apartSelf-Object PlayPlaying by themselves or with enrichment inside enclosures.Social BehaviorsDescriptionAffiliative SO(AF)Play, grooming, sexual behavior (copulating, sexual tonguing, exploratory behaviors: smelling the female’s genitalia, urine, or vaginal discharge (Carpenter, 1934, Horwich, 1983)). Agonistic SO(AG)Aggressive threat, back arching, branch shaking, howling at another individual, piloerection, throat rub, or genital displays.Human-Howler BehaviorsDescriptionApproaching Humans AHMoving toward the direction of people, resting on human, playing with human or requesting play from them.Approaching Humans AH(AG)Aggressive threat, back arching, branch shaking, howling, piloerection, throat rub, or genital displays at the sight of human.Table 5. Ethogram of social interactions between in A. pigraTroop LocationEight howlers (one group of four and two pairs between the ages of 3 and 5 years) were released into the Fireburn Reserve in June 2017. However, post-release observations were only possible on one released male-female pair (Darwin and Sansa). However, aA second pair was later introduced (Kat and Balou) when they came into contact with my primary subjectsthe first pair. Troops were located daily using auditory cues through exploration and auditory means with the assistance of Wildtrack’s staff. For example, oOn the first day, we began our exploration at the location of thefollow at the release cages. We sought out the tallest trees in the area, as well as noises in the branches forand listened for any sign of howlers. Once we located our group, we followed their every movethem until they settled in for the nighttheir sleeping tree, which usually took placetypically occurred around 1800. We then flagged the area we last saw them in and returned to the same site the following morningday at 0500. Because many howler groups demonstrate site-faithfulness and have been observed occupying the same home range annually (Horwich and Lyon 1990, Crocket 1996, Pavelka et al. 2003, Campbell et al. 2011), this method proved to be the most effective for locating our the group.Identification of Troops and IndividualsThe identification of the Rrehabilitated monkeys was performedwere identified using a method of identification tested at the siteWildtracks by Anthony Denice (during him time as a CWU student conducting graduate research), which has proven effective for identifying spider monkeys (Denice, 2017). This method uses photographss of faces and genitals of theache individuals during their time at the the primate rehabilitation center. Because each howler monkey (both males and females) has a unique pink shape on its posterior (Horwich, 1983b; Tricone, 2015), photographs of the face have beenwere taken from the front side of the howler, while the rear photographs were taken from an angle demonstrating the “continuity between the anus, perineum, and urogenital” (Tricone, 2015). Because a howler’s face can change substantially during maturation, as well as the challenge of not being able to viewlow visibility of their faces up in the canopy, this method proved to be the most efficient method tofor identifying howlers in the canopy. Identification of Protocols and Procedures To identify all protocols and procedures in place at Wildtracks, I created a checklist based on the guidelines listed by the IUCN, as presented by (Guy et al., (2014) (Table 7), as these guidelines are considered “best practice” and deemed important to optimize successful rehabilitation and reintroduction. I then compared the two to determine how much of Wildtracks’ approach was adopted from the IUCN guidelines listed by the IUCN (because these guidelines are meant to maximize positive outcomes) and how much of the approach is taxon-specific forto that region. The goal was to make this information accessible to other rehabilitation and re-introduction projects to ensure that they achieve their conservation goals with minimal side effects to the individuals being re-introduced. Table 7. Summary of protocols in place at Wildtracks in comparison to IUCN guidelines for nonhuman primate re-introductions (Guy et al., 2014, p. 163-164). Check marks indicate that procedures are in place, asterisks indicate that some procedures are missing, and no mark indicates that no protocols are in place.StagesIUCN Guidelines26 FactorsWildtracks ProceduresNotesArrivalQuarantine (;31 days)Clinical Examination Disease Screening Vaccines History collectionQuarantine Medical AssessmentVaccinesYesYesYesMissingQuarantine (min 31 days)Medical Assessment**Vaccines No Vaccines GivenMinimum 31 daysAssessmentHistory CollectionGenetics Socioecology and BehaviorYesMissingYes Genetics / geographical origin (Missing)History (e.g., wild, ex-pet, orphan)BehaviorNo Genetic WorkRehabilitationReduce Human ContactFree of StereotypesNatural Enclosures Natural Enrichment Natural GroupingNatural BehaviorNatural Food YesYes*YesYesYes* *Natural foodNatural enclosuresEnvironmental enrichmentResocialization with conspecificsReduce human contactGroup formation (behavior, compatibility, size ; composition similar to wild)Nursery Stage is Provided with Dog Toys (Kongs).Diet Contains Natural and Unnatural Foods.Prerelease AssessmentHealth/Disease ScreeningAssess Release SiteBehavioral Assessment Reduce Human Contact*YesYesYesBehavior Response to predators (Missing)Foraging abilities*Health checkFurther reduce human contactRelease site (predators, food ; water, wild conspecifics, habitat type, protection status)General Health and Fecal Testing Conducted Periodically. No Other Disease Screening.ReleaseTransport PlanSoft Release YesYesTransport planSoft release (acclimatize in enclosure, supplemental food and water)Post-releaseLong Term Monitoring Periodic Assessment of Success and Success CriteriaYesYesMonitor (min. 1 year)Establish and assess criteria for successProposed Criteria for Assessing the Suitability of A. pigra for ReleaseAccording to the IUCN’s guidelines for reintroduction, “released animals should exhibit behaviors essential for their survival and reproduction, and for compatibility with conspecifics.”. However, many ex-pets and rescued primates do not acquire the same skill level to survive in the wild as their wild conspecifics (Cheyne, 2009). For this reason, it is crucial to perform an evaluation of individuals being re-introduced to assess their capacity to survive in the wild. Below, I have highlighted the important aspects of wild howler behavior that rehabilitated individuals must master prior to their release, and which were used in this study to create an ethogram of howler behavior.Activity: According to Silver et al. (1998) Tthe activity and dietary profiles of Alouatta pigra in northern Belize is almost identical to that reported for other members of the genus in other areas (Silver et al., 1998). Alouatta pigra in northern Belize spends 61.9% of its time inactive, 24.4% feeding, 9.8% locomoting, 2.3% engaged in social activities (playing and grooming), and 1.5% vocalizing. A similar dietary profile has been observed in southern Belize by Pavelka & Knopff (2004), who reported with a general level of inactivity at 66.33%, followed by 18.57% spent feeding, 7.49% locomoting, and 3.6% spent socializing (Pavelka & Knopff, 2004, p. 107). Social Behaviors: Howler troops are maintained using a combination of friendly and aggressive behaviors directed between and within troops (Horwich & Lyon, 1990). Play: Young howlers within a troop exhibit higher frequencies of play behavior. They will typically chase or wrestle each other, while giving low-pitched play grunts (Horwich & Lyon, 1990). Play behavior is important as it serves a key role in sensory, motor, social, and cognitive development (e.g., Fagen 1981, 1993; Spinka et al., 2001), which can be used later in life to “capture prey, avoid predators, ?ght with conspeci?cs, attract a mate, or in infant caretaking” (e.g., Fagen, 1981; Smith, 1982). Aggression:Howling: Howlers are infamous for their loud vocalizations that can be heard throughout the day when theyhowlers hear loud noises, before it rains, and when others are feeding. They are most common at dawn and dusk (Horwich & Lyon, 1990).Aggressive threat: Adult males will exhibit aggressive behaviors when threatened., Tthey often will exhibit piloerection, which serves as a warning to its aggressor. They then raise and hunch their shoulders, while quickly leaning forward and grasping a tree branch (Horwich & Lyon, 1990).Aggressive throat rubbing: Male howlers also convey an angry message to other males using a gland on their throat region that leaves a scent after the male has rubbed his chest and throat on an object (Horwich & Lyon, 1990). Grooming: Grooming behavior, a widespread practice in many monkeys to maintain group peace, is rarely documented in howlers. However, when it is observed, it typically occurs between a male and female in a relaxed situation (Horwich & Lyon, 1990). Copulation: Reproductive success will be determined by the presence of mating behavior (Van Belle & Bicca Marques, 2015; Horwich, 1983a)Foraging behavior: The inability to find food in natural environments poses a major problem for rehabilitation and release programs and is often associated with poor post-release survival rates (Britt et al. 1999; Cheyne 2009; Frantzen et al. 2001; Mills 1999). A survey response from rehabilitation centers associated with A. pigra, reported that they require assistance to recognize palatable foods (Guy et al., 2013). For this reason, it is important to evaluate the dietary profile of rehabilitated howlers prior to their release. The howler diet consists primarily of young leaves and fruit, with young leaf consumption averaging 37.2% and fruit averaging 40.8% of their monthly diet. However, mature leaves were consumed 7.9% of the time. On the other hand, flowers averaged 10.2% of their monthly feeding time, but flower consumption peaked during the dry season, making up 36.8% of their monthly feeding time (Silver et al., 1998).Height in canopy/observed on the ground: Wild howler monkeys are an arboreal primate species that lives high in the canopy of tropical rainforests. They generally avoid coming to the ground, but will occasionally descend to the ground to cross gaps between trees in highly fragmented forests (Pozo-Montuy & Serio-Silva, 2008). Nonetheless, arboreal species usually avoid being on the ground, as it poses an increased risk of predation. When released, it is important that howlers remain in the canopy and are not seen travelling near the ground.Observed attracted to humans: All howlers at the primate rehabilitation center have interacted with humans in some form during their time in captivity. As a result, many have become dependent on humans. Due to their dependence on humans during captivity, many of these primates demonstrate a low chance of surviving post-reintroduction. For this reason, it is important to provide A. pigra with semi-wild enclosures with limited human contact to ensure their independence from humans and enable their survival in the wild (Baker, 2002).Locomotion: Howlers are highly arboreal, containing prehensile tails that serve as a fifth limb, to grasp branches and anchor the body during feeding time and locomotion (Marsh et al., 2008; Campbell et al., 2011).Group Cohesion: Group cohesion is important for survival, territory defense, and raising successful offspring. Howlers feed, sleep, and travel together (Horwich & Lyon, 1990). For this reason, group cohesion is taken into consideration in this study and measured through proximity to conspecific.DATA ANALYSISI conducted a cross-population study of rehabilitant howler monkeys from various sources and in various stages of the rehabilitation process to determine behavioral repertoire differences. I utilized the R software program (R Core Team, 2017) for all statistical computations and graphics. For scan and all occurrence sample data, I calculated the frequency that each group (nursery, forest cage one, forest cage two, and post-release) was observed on the ground (G), interacting with humans (AH), feeding (FD), resting (RE), vocalizing (VO), socializing (affiliation, SO (AF); aggression, SO (AG)), locomoting (LO), and playing by themselves or with an object (S (OP)). After calculating frequencies, I calculated the proportions of behaviors and compared the proportions observed across the different stages of rehabilitation. To determine the relationship between captive-type (e.g., amount of times observed on the ground (G) or interacting with humans (AH)) and wild-type behaviors (the proportions at which each individual was observed at different enclosure heights, foraging, locomoting, socializing or in close proximity to conspecifics) and age and time in rehabilitation, I conducted two correlation analyses. Pearson’s parametric correlation was used when the data was normally distributed. Kendall’s nonparametric correlation analysis was used when the data was not normally distributed and could not be transformed. Kendall’s correlation analysis was used over Spearman’s to reduce error associated with ties in the dataset. In this analysis, a value for p or r varies between +1 and -1, the first one indicating a perfct positive correlation and the latter, a perfect negative correlation. A value of 0 indicates that there is no correlation between the values of x and y (behaviors and time spent in rehabilitation). The null hypothesis is that there is no correlation between the variables (r=0) and the alternative indicates that there is a relationship between the variables (r0).The data met all assumptions of the Pearson’s correlation parametric test (random sampling, linear relationship, interval data). To test for normality, I performed the Anderson-Darling test, which indicated that age, time spent in rehabilitation, and average proximity to conspecifics were normally distributed. Average height spent in the trees was not normally distributed, neither were the counts for AH, G, FD, or SO(AG), and transformation was not possible. Consequently, Kendall’s non-parametric correlation analysis was used and all tests were analyzed using an ?0.05. RESULTSProportion of Total Behaviors ObservedAll behaviors across all rehabilitant howler groups were examined, and howlers were most often resting (57.28% of the time) or feeding (18.20%) followed by locomoting (8.18%), socializing with conspecifics (6.53%) or humans (6.27%) and playing (2.62%). Rehabilitants were observed on the ground 0.94% of the time. Vocalizations occurred in 9.93% (N=1,603) of observations. No stereotypic behavior was observed. Proportion of Behaviors Observed per GroupThe nursery group (Roxy, Jade, Puck, Clifford) spent the majority of its time at rest (39.98%) followed by interacting with humans (14.26%), feeding (14.13%), socializing (11.84%), locomoting (9.32%), and self-object play (6.38%). Howlers in the nursery often vocalized (31.33% of the time) and spent the most time on the ground (2.50%) out of all rehabilitant groups (Figure 2). Figure 2. Frequency of behaviors observed in the nursery rehabilitant group.The forest cage one group (Jo and Brea) spent 73.24% of its time resting, 14.80% feeding, 6.27% interacting with humans, 3.87% socializing, and 1.81% locomoting (Figure 3). This group was not observed on the ground and did not engage in play. Vocalizations were heard in 1.27% of observations.Figure 3. Frequency of behaviors observed in the forest cage one rehabilitant group.Compared to forest cage one, the forest cage two group spent less time resting (45.50%) and interacting with humans (3.26%) and more time feeding (30.21%), locomoting (11.14%) and socializing (7.41%). These rehabilitants also engaged in self-object play (2.21%) and were observed on the ground (0.26%) (Figure 4). Vocalizations were heard in 1.38% of observations.Figure 4. Frequency of behaviors observed in the forest cage two rehabilitant group.The post-release group (Darwin, Sansa, Kat, and Balou) spent 65.64% of their time resting, 9.63% feeding, 5.56% locomoting, 0.63% socializing, 0.26% on the ground, and 0.16% interacting with humans (Figure 5). Vocalizations were heard in 0.79% of observations.Figure 5. Frequency of behaviors observed in the post-release rehabilitant group.Time and BehaviorTo compare the effect of time spent in rehabilitation (in months) on behavior, I ran a set of correlations. Significant negative relationships were found between time spent in rehabilitation and time spent interacting with humans (tau= -0.66, p=.002) (Figure 6), time spent on the ground (tau= -0.57, p=.009) (Figure 7), and time spent engaging in affiliative social behavior (r= -0.63, df=11, p=.01). A significant positive relationship was found between time spent in rehabilitation and average height observed in the trees (tau=.61, p<.001) (Figure 8). Figure 6. Negative relationship between the frequency of human-howler interactions and time in rehabilitation (Kendall’s tau=-.66, p=.002).Figure 7. Negative relationship between the frequency of howlers observed on the ground and time in rehabilitation (Kendall’s tau= -.57, p=.009).Figure 8. Positive relationship between average height observed in trees and time in rehabilitation (Kendall’ tau=.61, p=.003).Age and BehaviorBecause the frequency data yielded differences in observed behaviors across the different rehabilitation stages with individuals of different ages, I ran a set of correlations to investigate the effects of age on behavior. Significant negative relationships were found between a rehabilitant’s age and time spent on the ground (tau= -.70, p<.001) (Figure 9), time spent interacting with humans (tau= -.50, p=.01) (Figure 10), time spent in social affiliative behavior (r= -.75, df= 11, p= .00) and time spent playing alone or with an object (tau= -.78, p<.001). A significant positive relationship was found between a rehabilitant’s age and average height observed in the trees (tau=.71, p; .001) (Figure 11). Figure 9. Negative relationship between time spent on the ground and age (Kendall’s tau=-.70, p<.001).Figure 10. Negative relationship between human-howler interactions and age (Kendall’s tau= -.50, p;.001).Figure 11. Positive relationship between average height spent in trees and age (Kendall’s tau=.55, p=.008).Non-significant ResultsIn this study, no significant differences were found between time spent in rehabilitation and time feeding (tau= -.24, p= .24), locomoting (r=-.08, p=.77), engaging in social agonistic behavior (tau= .17, p=.44), or average proximity to conspecifics (r=.39, df=7, p=.29). Differences in age were also not significantly correlated to feeding (tau= -.19, p=.35), time locomoting (tau= -.36, p=.22), time resting (tau=.40, p=.05), time engaging in social agonistic behavior (tau=.02, p=.89), and average proximity to conspecific (r=.23, df=7, p=.54) (see Figure 12-14). Figure 12. Frequency of proximity observed in F1.Figure 13. Frequency of proximity observed in F2.Figure 14. Frequency of proximity observed in PR.DiscussionThe activity pattern of rehabilitant howlers followed the typical howler behavior pattern reported in the literature (Silver et al., 1998; Pavelka and Knopff, 2004; Prates and Marques, 2008) and was similar to that reported by Pavelka and Knopff (2004) for the population of A. pigra at the Monkey River site in southern Belize. Howlers at Monkey River typically spent an average of 66.33% of their day inactive followed by 18.57% feeding, 7.49% locomoting, and 3.6% socializing (Pavelka and Knopff, 2004, p. 107). This activity budget is expected, as howlers are known for spending more time inactive and less time socializing than many other primate species (Baldwin and Baldwin, 1978; Silver et al. 1998; Estrada et al., 1999; Pinto et al, 2003). A high level of inactivity is often correlated with their mostly folivorous diet and is thought to be in response to the consumption of low-quality leaves (Milton 1980). Such leaves require an extended period of digestion and fermentation in the gut (Horwich and Lyon, 1990). Because much of a howler’s time and energy is devoted to digesting plant material, they have little energy to devote to being social (Baldwin and Baldwin, 1978). However, more recent studies challenge this notion. Pavelka and Knopff (2004) argue that activity levels may be phylogenetically constrained because howlers maintain a sedentary lifestyle even during times of high fruit availability. It is also important to note that behavior varied between the different stages (see figures 2-5).PredictionsThe results of this study support the predictions that as time in rehabilitation increased, the behaviors of rehabilitant howlers would become more similar to the behaviors of their wild counterparts. Rehabilitants would decrease stereotypic behaviors, increase naturalistic behaviors (e.g., social interactions; group cohesion (measured through proximity); greater heights in trees), and decrease behaviors associated with human dependency (e.g., approaching humans). In addition, we would expect older individuals with more time spent in rehabilitation spending less time engaging in unnatural behaviors (e.g., interacting with humans; coming down to the ground; remaining low in the trees) than younger individuals in earlier stages of rehabilitation. Human-Howler InteractionsHigher levels of human-howler interactions in group N1 were expected, primarily because in this rehabilitation stage, young howlers typically have a caregiver with them for an average of 8-10 hours per day. In the wild, non-human primates experience extensive parental care and long periods of infant and juvenile dependency (Yeager, 1997), resulting in strong social relationships between the mother and her infant. This is especially true in primate species that do not establish permanent sexual partnerships (Altmann, 1959). Often these relationships are mutual, affectionate, emotional, long-lasting and often characterized by a set of affiliative behaviors (allogrooming, provision of nourishment, warmth, protection, and maintaining close proximity) that allow for the transmission of information essential for the survival of the infant (Newberry and Swanson, 2007). Hence, a caregiver remains in close proximity to howlers in this stage to help them better adapt to separation from their mothers and reduce the negative impact associated with early (potentially traumatic) separation (e.g., cognitive impairment, depressed immunity, unresponsiveness, listlessness) (de Waal, 1996; Boccia et al.,1997). However, as howlers get older and move further along in the stages of rehabilitation, we can expect to see a reduction in human dependency. I did not expect to see individuals interacting with humans in F1 and F2 groups because Wildtracks reduces human contact to feeding times at these levels of rehabilitation. Indeed, human-howler interactions were limited to feeding times. This is a potential area for procedural improvement to further minimize human-howler interaction in this critical intermediate rehabilitation stage. I believe these interactions resulted from carelessness and poorly managed volunteers. With the PR group, interactions with humans were minimal and only observed after a fight between two adult male howlers. These human-howler interactions were mainly aggressive (e.g., howling at human observers).On the GroundNone of the F1 group members were observed on the ground. However, howlers in the N1, F2, and PR groups were observed coming down to the ground, but this behavior was rare. Nonetheless, this behavior still made up less than 3% of the N1 group’s activity and can be explained by the caregiver’s position within the enclosure. Caregivers typically sat on the ground in the far-right corner of the enclosure to avoid getting urine or feces on them. During infancy, howlers typically remain in close proximity to the mother, as it provides opportunities for the mother to transmit information to her young, such as, information about food sources and predators (Newberry and Swanson, 2008). Young howlers have also been observed playing with the mother’s fur, ears, and limbs, as well as resting and crawling on the mother’s body (Baldwin and Baldwin, 1978). This was also the case with N1 howlers. Many of the howlers were observed playing (e.g., biting caregiver, wrestling on them), resting on or next to the caregiver, and exploring the caregiver’s body (e.g., playing with hair, reaching for eyes). Howlers in the N1 group were observed on the ground at a much higher frequency than all other groups. In F2, individuals came down to the ground during play and at feeding times when a caregiver was present. Individuals typically wrestled with each other and when wrestling became too aggressive, they would drop to the ground, travel to the other side of the enclosure and climb back up into the trees. One particular individual, Anerie, had the tendency to hang by her tail (1.5m high), drop to the ground, sit there for a few seconds, and then climb back up to the top of the enclosure. In PR, only Darwin was observed on the ground. On one occasion, Darwin came down to the ground after noticing our presence. He came down to a height of approximately two meters then proceeded to rest on the ground. The next day, Darwin was observed engaging in the same behavior after noticing our presence. This behavior was alarming, as wild howlers are recognized as being arboreal with locomotion adapted to an arboreal lifestyle (Carpenter, 1934). Although this behavior is rarely seen in the wild, Carpenter (1934) reports having personally seen a wild group travelling on the ground near the bank of a stream, as well as locals observing howlers coming down to the ground to travel from one group of trees to another. They generally avoid coming to the ground but will occasionally to cross gaps between trees in highly fragmented forests (Pozo-Montuy & Serio-Silva, 2008). Nonetheless, terrestrial locomotion is not the preferred mode of travel for the genus Alouatta (Carpenter, 1934) and was rarely observed in the latter stages of rehabilitation.HeightBecause howler monkeys are highly arboreal with locomotion adapted to an arboreal lifestyle (Carpenter, 1934), I expected height to increase as individuals matured and spent more time in rehabilitation. The results indicated a positive correlation between age, time in rehabilitation, and average height in trees. However, 8 out of 13 individuals sampled, (individuals 9-61 months old with 4-25 months in rehabilitation) were observed, on average, at heights ?1m. The PR group was the exception. Individuals in PR (38-41 months old with 20-34 months in rehabilitation) were observed, on average, at heights 10m. We did not predict rehabilitants would spend most of their time in the lower half of their enclosures, as this is not common in arboreal species. In the wild, howlers can typically be found feeding and travelling high in the upper part of the canopy and are seldom observed in the understory (Carpenter, 1934; Smith, 1977). One potential reason for a lower average height was that individuals in N1, F1, and F2 were confined to 3.3-m enclosures (Table 5), which limited their arboreal mobility. At Fireburn Reserve, the PR group was surrounded by trees >15m, but these individuals were observed, on average, in trees measuring 10.57m. These results are similar to those reported by Estrada et al. (2003) for the population of A. pigra at the Mayan sites of Calakmul, Yaxchilan, Mexico and Tikal, Guatemala. Howlers at the Fireburn Reserve were sighted, on average, at heights between 6-10 and 11-15 meters. Social AffiliativeAge and time in rehabilitation were negatively correlated to socially affiliative behavior, meaning that younger individuals with less experience in groups N1 and F2 socialized at a much higher frequency than groups F1 and PR. These results were unexpected; as socially affiliative behaviors were being used in this study to measure group cohesion. Hence, we expected to see howlers in later stages of rehabilitation socializing at much higher frequencies than younger, unexperienced individuals. Although intragroup social interaction was observed in all stages of rehabilitation, the N1 and F2 groups had higher frequencies, predominantly play behavior. Play behavior is common amongst infants and juveniles, as it plays a critical role in the development and socialization of young animals (Baldwin and Baldwin, 1978; Fagan, 1981). It provides younger animals experiences that teach them social skills (e.g., sexual behavior, maternal behavior, controlled aggression) and expedite the process of integration into a social group (Baldwin and Baldwin, 1978). F1 was mainly observed engaging in mating behavior (sexual tonguing, copulating, genital licking) (Horwich and Lyon, 1990). PR was only observed engaging in agonistic social behavior, primarily after the PR group (Darwin and Sansa) came into close contact with another release group (Kat and Balou). At the sight of Balou, Darwin began to display a series of agonistic behaviors (e.g., piloerection, raised and hunched shoulders). Balou recognized the threat and attempted to run away, but Darwin approached piloerect and proceeded to attack him. The confrontation ended with Darwin knocking Balou out of the trees. Balou landed on a lower branch, but Darwin continued to chase him off. Balou finally dropped to the ground and ran off. This intergroup encounter is not unexpected, and although many howler species are not strictly territorial, they do not tolerate other groups in their immediate area (Horwich and Lyon, 1990). Although affiliative behavior is rare in many howler species, grooming between Darwin and Sansa was observed (Campbell et al., 2007; Horwich and Lyon, 1990).Non-significant ResultsIn general, one would expect to see variation in behavior between the different stages of rehabilitation because of the separate requirements of the different sex and age classes (Marques and Marques, 1994). For example, infants and juveniles may require more energy from food than a larger inactive individual to aid in their development, while females may have different requisites to increase reproductive success (Marques and Marques, 1994; Pavelka and Knopf, 2004). On the other hand, adult males have been observed spending less time feeding and more time resting than females or young animals. This phenomenon has been observed across different primate taxa (Alouatta villosa, Indri, Theropithecus gelada, Cercocebus albigena) and has primarily explained by the fact that males do not incur the costs of pregnancy and lactation (Clutton-Brock, 1977; Smith, 1977). The latter has been supported by Smith (1977) who observed females with dependent offspring spending more of their day feeding (18%) than males (14%), and females without dependent offspring. However, in sexually dimorphic species, males are also expected to consume more than females and younger individuals to sustain their larger bodies (Clutton-Brock, 1977).ProximityThe results of this study revealed that there were no significant differences between age, time, and average proximity to conspecifics. Proximity data revealed that F1, F2, and PR spent most of their time between 0 to 2 meters in proximity to conspecifics (see figures 12-14), signifying group cohesion. This may be due to the fact that many of these individuals have been undergoing rehabilitation together since an early age. ConclusionRehabilitation and release of primates as a conservation strategy has not been well assessed in the primate literature (Guy et al., 2014). The goal of this study was to assess the approach to rehabilitation and release of black howler monkeys (Alouatta pigra) at Wildtracks, Belize. Because this organization has had a successful rehabilitation program in place for over ten years, it was important to assess their techniques and make this information accessible to other rehabilitation and re-introduction projects. However, from my observations, like many other rehabilitation and release programs, Wildtracks fails to implement all procedures outlined by the IUCN (Baker, 2002). Despite this, Wildtracks continues to demonstrate high rates of survival for rehabilitated monkeys (Tricone, 2018). In addition, in this study, rehabilitants demonstrate a significant reduction in unnatural behavior, as individuals move into the further stages of rehabilitation. Certainly, Wildtracks has offered many captive individuals a better quality of life and contributed to the preservation of wildlife biodiversity through the re-establishment of viable populations of threatened species. Nonetheless, to further strengthen reintroduction protocols already in place at Wildtracks, I have outlined a set of recommendations based on my observations: I recommend redefining the projects objectives, establishing a multi-disciplinary team, reassessing the carrying capacity of the release site, taking measures to reduce behavioral aberrations, conducting thorough medical examinations before and after release, ensure all staff members are in good health, and increasing the size of the soft release enclosure to further strengthen acclimatization to release site.For this study, I conducted a cross-population study between rehabilitants from various sources and in various stages of the rehabilitation process to determine behavioral repertoire changes differences between atthe different stages of the rehabilitation process. I utilized the R software program for all statistical computations and graphics (R Core Team, 2017). For scan and all occurrence sample data, I calculated the frequency at which each group (e.g. e.g., nursery, forest cage one, forest cage two, and post- release) was observed on the ground (G), interacting with humans (AH), feeding (FD), resting (RE), vocalizing (VO), socializing (SO (AF); SO (AG)), locomoting (LO), and playing by themselves or with an object (S (OP)). After calculating frequencies, I calculated the proportions of behaviors and compared the proportions observed across the different stages of rehabilitation. To determine whether unnatural behaviors (e.g. e.g., the amount of times observed on the ground (G) or interacting with humans (AH)) decreased, as time in rehabilitation increased, and naturalistic behaviors (the proportions at which each individual was observed at different heights, foraging, locomoting, socializing or in close proximity to conspecifics), were related to each other in some consistent linear way and to test the strength of the relationship, as well as the direction of the relationship (positive or negative): I conducted two separate correlation analyses. Pearson’s parametric correlation analysis was used when the data was normally distributed and transformation was possible. Kendall’s non-parametric correlation analysis was used when the data was not normally distributed and could not be transformed. Kendall’s correlation analysis was used over Spearman’s to reduce error associated with ties in the dataset. In this analysis, a value for p or r varies between +1 and -1, the first one indicating a perfect positive correlation and the latter, a perfect negative correlation. A value of 0 indicates that there is no correlation between the values of x and y (behaviors and time spent in rehabilitation). The null hypothesis is that there is no correlation between the variables (p=0) and the alternative indicates that there is some relationship between the variables (p0).The following data met all the assumptions of the Pearson’s correlation parametric test: the sample from the population under study is random, the relationship between the two variables is linear, and measurements of both variables is on the interval scales. Pearson’s correlation test also requires both variables to be normally distributed. To test for normality of the variables, I utilized the Anderson-Darling test in R, which found the estimated age of individuals, the amount of time each individual spent in rehabilitation, and average proximity to conspecific normally distributed, with the exception of average height spent in the trees and the following observed behaviors: AH, G, FD, SO(AG). To make average height spent in trees variable fit a normal distribution, I used a log transformation code in R to transform the variable associated with average height spent in the trees and retested for normality. For variables AH, G, FD, SO(AG), transformation was not possible. Consequently, Kendall’s non-parametric correlation analysis was used.A regression analysis was also used in this study to test if estimated age or time spent in rehabilitation significantly predicted the average height rehabilitants spent in trees and average proximity to conspecifics. The following analysis uses a line equation (y=bx+a) to describe the relationship between two different variables that can predict values of y (proximity) at a particular value of x (time or age). In this formula, a=y-intercept and =slope of the line or the regression coefficient. The null hypothesis is determined from the slope of the line; H0: =0 and the alternative hypothesis is HA: 0. The following data, met all the assumptions of regression analysis. The relationship between the variables is linear, all observations are independent (each individual was only measured once, the sample from the population under study is random, the residuals of y are normally distributed (with the exception of average height spent in trees) with equal variance at all x-values, and values of y are on a continuous scale. Again, a log transformation code was used in R to transform the variable associated with average height spent in the trees and the variable was retested for normality until it yielded a p value ;.05RESULTSProtocols and Procedures in Place at Wildtracks for Pre-ReleasePrior to arrival at the rehabilitation center, the staff at Wildtracks collects as much information (as possible) from the locals or authorities. Then, a physical assessment of the howler’s condition is performed. When assessing a howler’s condition, they look at their coat and weight for any obvious signs of ailments. A howler is considered to be in “good condition” if they demonstrate long, silky, dense black fur (Richardson, 2006; American Zoo, 2006) and are of the average weight for a male or female howler (Richardson, 2006). Poor condition is determined by poor fur and weight. If a howler appears to be seriously injured or highly emaciated, then veterinary care is provided. However, this is usually avoided due to lack of access to resources and good veterinary care.Arrival (Quarantine)Quarantine procedures are in place at Wildtracks. Upon arrival, every howler is placed in an 8’x8’x9′ ft. quarantine enclosure where they remain for a minimum of 30 days until they’re medically cleared.Arrival (Medical Assessment/Vaccines)Fecal samples are collected and tested for parasites (giardia, mange, roundworms, hookworms). Pyrantel is given to treat roundworms and hookworms. Serious cases of mange and giardia are assessed by a local veterinarian and treated with medication. However, vaccines are not given to howlers, as they’re not deemed necessary by the staff at Wildtracks. Assessment (Genetics/ Geographical Origin)No genetic information exists for rehabilitants and geographic origin is difficult to determine without genetic information.Assessment (History)A behavioral assessment based on howler behavior found in the literature is done by the staff to determine whether an individual is from a wild population, ex-pet, or orphaned. For example, criteria similar to the one mentioned above: proposed criteria for assessing the suitability of A. pigra for release is used determine the source of a rehabilitant. However, most of this information is determined from the context in which the individual was found in or behavioral repertoire.Rehabilitation (Natural Food)Howlers are not provided with a fully natural diet. They are fed a combination of fruit (watermelon, papaya, banana, mango, apples), not found in their natural habitat and leaf browse that does grow naturally at their release site. For example, species such as bri-bri and ramon are commonly given to encourage foraging skills. Young howlers and individuals below the average weight for a howler, are given Ensure as a replacement for milk and source of protein to help them regain their strength and obtain a healthy weight. Rehabilitation (Natural Enclosures & Environmental Enrichment)Enclosures vary in size (see Table 8 in appendix). Young howlers in early stages of rehabilitation are provided with enrichment (ropes, swings, hammocks, kongs), lianas, and wooden structures to help them develop climbing skills. In the forest cage stage of rehabilitation, only natural wooden climbing structures, ropes, lianas, and hammocks are provided to promote more naturalistic movements across the enclosure. Pre-release enclosures are large patches of forest surrounded by electric fencing, containing trees similar to those found at their release site. However, within the enclosure they still contain a small cage where howlers can find fruit and water that is provided as a supplement by their caregiver. These enclosures do not contain enrichment and are arranged similar to their natural habitat with natural trees similar to the ones found at their release site. Pre- release enclosures are divided into three separate enclosures (pre-release one, two, and three). Pre-release one contains smaller trees than pre-release two. Pre-release two contains trees larger than pre-release one, but smaller than pre-release three. These enclosures are set up in this way to help newly introduced howlers adjust to new heights in the trees. Pre-release Assessment (Behavior and Foraging)Staff routinely assesses group cohesion, locomotor, and foraging skills before moving individuals to new stages in rehabilitation (P. Walker, personal communication, November 15, 2016). For example, young howlers that demonstrate group cohesion, confidence in their foraging abilities, and locomoter skills can be considered for the forest cage stage of rehabilitation. As you move further into the rehabilitation process there should be an increase in naturalistic behavior like the one listed in the proposed criteria for release. Volunteer caregivers are also encouraged to report any abnormal behavior in rehabilitants. However, these reports aren’t always consistent and dismissed if an individual is not familiar with natural primate behavior.Pre-release Assessment (Predators)No predator response training is in place at this moment. Pre-release Assessment (Health Check)In this case, a dose of pyrantel and anti-parasite medication based on individual weight was given to rehabilitants before being moved to the transport crate. Fecal examinations are conducted routinely to determine parasitic infection, but from my observations no pre-release health assessments exist, unless there are clear signs of physical ailments. Pre-release Assessment (Further Reduce Human Contact)During this time, they are still provided with supplemental food, but human and howler interaction is limited to feeding. Pre-release Assessment (Release site (Predators, Food ; Water, Wild Conspecifics, Habitat Type, Protection Status))The suitability of the Fireburn Reserve as a release site was last assessed by Fanigliulo in 2005. The following study determined that the Fireburn Reserve could sustain growing numbers of re-introduced populations (in terms of food abundance and canopy structure) (Fanigliulo, 2005). However, no other assessments of the site have been conducted since then. The last population study was conducted by researcher, Fanny Tricone in (2015), but more recent population numbers are limited to tracker’s knowledge and difficult to determine. Release (Release Transport Plan)Individuals were put into kennels and transported by boat to the reserve. After arrival, they were zip-tied to large bamboo sticks and carried by the volunteers to their release site, which was about a mile and a half from the drop off location. Release (Soft release (Acclimatize in Enclosure, Supplemental Food and Water))Soft release enclosures are similar to the quarantine enclosures and measure about 8’x8’x9′ ft. Howlers remain in these enclosures for three days and continue to be provided with supplemental food and water. Volunteers and trackers are also encouraged to monitor their behavior and report any stress behaviors. However, from my observations, howlers that demonstrate stress behaviors may still be released.Post-Release (Monitor)Newly released individuals are monitored seven days a week for three months, then they transition to monitoring every other week for up to a year. Post-Release (Establish and Assess Criteria for Success)Proportion of Behaviors Observed Across the Different Stages of RehabilitationNurseryThe nursery group spent the majority of its time engaging in resting behavior (39.98%) and vocalizing (31.33%). Followed by, interacting with humans (14.26%), feeding (14.13%), socializing (11.84%), locomoting (9.32%), self-object play (6.38%), on the ground (2.50%).Forest Cage OneThe forest cage one group spent 73.24% of its time resting, 14.80% feeding, 6.27% interacting with humans, 3.87% socializing, 1.81% locomoting, and 1.27% vocalizing.Forest Cage TwoForest cage two spent 45.50% of its time resting, 30.21% feeding, 11.14% locomoting, 7.41% socializing, 3.26% interacting with humans, 2.21% engaging in self-object play, 1.38% vocalizing, and 0.26% on the ground.Post-Release GroupThe Post-Release Group spent 65.64% resting, 9.63% feeding, 5.56% locomoting, 0.63% socializing, 0.26% on the ground, 0.79% vocalizing, and 0.16% interacting with humans.Correlations between Time in Rehabilitation and BehaviorAt the beginning of this study, I predicted that as time in rehabilitation increased, rehabilitants would demonstrate a decrease in observed stereotypic behaviors, an increase in naturalistic behaviors (e.g., social interactions; group cohesion (measured through proximity), and a reduction in behaviors associated with human dependency (e.g., approaching humans, coming down to the ground). In this section, only significant results are presented. Across the different stages in rehabilitation, Kendall’s correlation analysis revealed that time in rehabilitation and the number of times howlers were observed interacting with humans was significantly correlated, tau=-0.66, p=.002. Time in rehabilitation was also significantly correlated to and number of times individuals came down to the ground, tau= -0.57, p=.009. Pearson’s correlation analysis revealed that affiliative social behavior and time in rehabilitation was significantly correlated, r=-0.63, p=.01. Time in rehabilitation was also significantly correlated to average height rehabilitants spent in the trees, r=0.80, p=.0009397 (Table 9).A regression analysis was used to test if time spent in rehabilitation significantly predicted the average height rehabilitants spent in trees. A significant regression equation was found between time spent in rehabilitation and average height rehabilitants spent in the trees =1.640, t (3.858) = .002, p;0.5). Time in rehabilitation also explained a significant proportion of variation in average height, R^2= .53, F (1,11) =14.88, p;.05. A regression analysis was also used to test if estimated age significantly predicted the average height rehabilitants spent in trees. A significant regression equation was found between estimated age and average height rehabilitants spent in the trees =2.0743, t (2.343) =.03, p;0.5). Time in rehabilitation also explained a significant proportion of variation in average height, R^2=0.2723, F (1,11) = 5.491, p;.05.AppendixTable 8. Enclosure Size Measured in Feet for Different Stages of RehabilitationEnclosureSize in ftGroupQuarantine8’x8’x9’HelenaNursery Outdoor12’x6’x7′ Ivy/Sean/Max/MayaNursery Indoor6’x4’x7’Ivy/Sean/Max/MayaNursery Indoor Backroom7.5’x 7.7′ x 8’Cliff/Roxy/Puck/JadeNursery Indoor4’x4’x7Cliff/Roxy/Puck/JadeNursery Infant10’x12’x7Piper/PrimForest Cage Double Enclosure 120’x12’x11 (2)Jo/BreaForest Cage Double Enclosure 28’x8’x8 (2)Bean/KenyaForest Cage 316’x16’x9’Anie/Anerie/MollyPre-Release 1n/an/aPre-Release 230492 sq ftn/aPre-release 328314 sq ftn/aMile 40 8’x8’x9′ (2)Mile 40 (4)Pachuco24’x9’x9’PachucoTable 9Correlations with confidence intervalsNote. 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