THE GREATER BAMBOO LEMUR

 

The greater bamboo lemur (Prolemur simus), also known as the broad-nosed bamboo lemur and the broad-nosed gentle lemur, is the largest bamboo lemur, at over five pounds or nearly 2.5 kilograms. It has greyish brown fur and white ear tufts, and has a head-body length of around one and a half feet, or forty to fifty centimeters. They have relatively long tails and long back legs for leaping vertically amongst the trees of their forest habitat. It feeds almost exclusively on the bamboo species of Cathariostachys madagascariensis, preferring the shoots but also eating the pith and leaves. It is unknown how their metabolism deals with the cyanide found in the shoots. The typical daily dose would be enough to kill humans. Greater bamboo lemurs occasionally consume fungi, flowers, and fruit. Its main food source is bamboo and it is the main reason why it has become critically endangered.^[4][5] Areas with high density of bamboo have major human disturbances, where humans cut or illegally cut down bamboo.^[6] Its only confirmed predators are the fossa and the bushpigs,^[7] but raptors are also suspected. Its current range is restricted to southeastern Madagascar, although fossils indicate its former range extended across bigger areas of the island, including as far north as Ankarana.^[8][9] Some notable parts of the current range are the Ranomafana^[10] and Andringitra National Parks.^{[citation needed]}

Greater bamboo lemurs live in groups of up to 28. Individuals are extremely gregarious. The species may be the only lemur in which the male is dominant, although this is not certain. Because of their social nature, greater bamboo lemurs have at least seven different calls. Males have been observed taking bamboo pith away from females that had put significant effort into opening the bamboo stems. In captivity, greater bamboo lemurs have lived over the age of 17.^[11]

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Conservation status

The greater bamboo lemur (Prolemur simus), is one of the world's most critically endangered primates, according to the IUCN Red List. Scientists believed that it was extinct, but a remnant population was discovered in 1986.^[12] Since then, surveys of south- and central-eastern Madagascar have found about 500 individuals in 11 subpopulations.^[1] The home range of the species is likewise drastically reduced. The current range is less than 4 percent of its historic distribution. The reason for the endangerment is climate change and human activities which depleted the primary food source (bamboo). Greater bamboo lemur is a part of prosimian species, which appeared even before monkeys. This species of lemur is not capable of adapting to the rapidly changing habitat. Human activities and climate change have resulted in the depletion of populations and resulted in a few remaining patches of forest capable of supporting this species. The species is endangered by the following: slash and burn farming, mining, bamboo, and other logging, and slingshot hunting.^{[11] [13][14]} It was formerly one of "The World's 25 Most Endangered Primates."^[15]

 

 

 Binomial name

Prolemur simus Gray, 1871[3]

THE COTTON -TOP TAMARIN

 

The cotton-top tamarin (Saguinus oedipus) is a small New World monkey weighing less than 0.5 kg (1.1 lb). This New World monkey can live up to 24 years, but most of them die by 13 years. One of the smallest primates, the cotton-top tamarin is easily recognized by the long, white sagittal crest extending from its forehead to its shoulders. The species is found in tropical forest edges and secondary forests in northwestern Colombia, where it is arboreal and diurnal. Its diet includes insects and plant exudates, and it is an important seed disperser in the tropical ecosystem.

The cotton-top tamarin displays a wide variety of social behaviors. In particular, groups form a clear dominance hierarchy where only dominant pairs breed. The female normally gives birth to twins and uses pheromones to prevent other females in the group from breeding. These tamarins have been extensively studied for their high level of cooperative care, as well as altruistic and spiteful behaviors. Communication between cotton-top tamarins is sophisticated and shows evidence of grammatical structure, a language feature that must be acquired.

Up to 40,000 cotton-top tamarins are thought to have been caught and exported for use in biomedical research before 1976, when CITES gave them the highest level of protection and all international trade was banned. Now,^[when?] the species is at risk due to large-scale habitat destruction, as the lowland forest in northwestern Colombia where the cotton-top tamarin is found has been reduced to 5% of its previous area. It is currently classified as critically endangered and is one of the rarest primates in the world, with only 6,000 individuals left in the wild.

 The cotton-top tamarin

Taxonomy and naming

 

 

 

S. oedipus has the common names "cotton-top tamarin" and "cotton-headed tamarin" in English. Its name comes from the white hair that spans its head and flows down past the neck.^[3] In Spanish, it is commonly called bichichi, tití pielroja, "tití blanco, tití cabeza blanca, or tití leoncito.^[2][4] In German-speaking areas, the cotton-top tamarin is commonly known as Lisztaffe (literally "Liszt monkey") most likely due to the resemblance of its crest to the hairstyle of Hungarian composer and piano virtuoso Franz Liszt.^[5]

The species was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae.^[2] as Simia oedipus.^[6] Linnaeus chose the specific name oedipus, which means swollen foot, but as the species does not have particularly large feet, it is unknown why he chose this name. (Linnaeus often selected names from mythology without any particular rationale, and he may have used the name of Oedipus, the mythical Greek king of Thebes, more or less arbitrarily.)^[7] In 1977, Philip Hershkovitz performed a taxonomic analysis of the species based on fur coloration patterns, cranial and mandibular morphology, and ear size. He classified Geoffroy's tamarin S. geoffroyi as a subspecies of S. oedipus.^[8] Subsequent analyses by Hernández-Camacho and Cooper (1976),^[9] Russell Mittermeier and Coimbra-Filho (1981),^[8] and later Grooves (2001)^[10] consider the S. oedipus and S. geoffroyi types to be separate species.

Some researchers, such as Thorington (1976),^[8] posit that S. oedipus is more closely related to the white-footed tamarin (S. leucopus) than to S. geoffroyi. This view is supported by Hanihara and Natoria's analysis of toothcomb dental morphology (1987) and by Skinner (1991), who found similarities between S. oedipus and S. leucopus in 16 of 17 morphological traits considered.^[8]

This species of white-headed tamarin is thought to have diverged from the other Amazonian forms such as S. leucopus. This is supported by morphological considerations of the transition from juvenile to adulthood, during which the fur coloration patterns change. significantly and are similar between the two species.^[11] Hershkovitz proposed that the separation of the two species happened in the Pleistocene at the height of the Atrato River, where it intersected the Cauca-Magdalena. At that time, the area was covered by a sea, which created a geographic barrier that caused the species to diverge through the process of allopatric speciation. Today, the two species are principally separated by the Atrato River.^[11]

 

Physical characteristics

 

 

The cotton-top tamarin is part of the most diminutive family of monkeys, Callitrichidae, the marmosets and tamarins; it weighs 432 g (15.2 oz) on average. Its head–body length is 20.8–25.9 cm (8.2–10.2 in), while its tail—which is not prehensile—is slightly longer at around 33–41 cm (13–16 in).^[11] The species is not sexually dimorphic, the male and female are of a similar size and weight.^[4] Members of the Callitrichinae subfamily (including this species) have sharp nails (tegulae) on all digits except the big toes, which have the flat nails (ungulae) common to other primates. Tegulae resemble a squirrel's claws and help with movement through trees.^[2][4]

The white hair on the back of the head and neck inspire its common name, "cotton-top".

The cotton-top tamarin has a long sagittal crest, consisting of white hairs, from forehead to nape flowing over the shoulders. The skin of the face is black with gray or white bands located above the eyes. These bands continue along the edge of the face down to the jaw.^[12] Tamarins are generally divided into three groups by their facial characteristics: hairy-faced, mottled-faced, and bare-faced. The cotton-top tamarin has fine white hair covering its face, but they are so fine as to appear naked, thus it is considered a bare-faced tamarin. Its lower canine teeth are longer than its incisors, creating the appearance of tusks.^[13] Like other callitrichids, the cotton-top tamarin has two molar teeth on each side of its jaw, not three like other New World monkeys.^[2]

The cotton-top tamarin has fur covering all of the body except the palms of the hands and feet, the eyelids, the borders of the nostrils, the nipples, the anus, and the penis. The back is brown, and the underparts, arms, and legs are whitish-yellow. The rump and inner thighs and upper tail are reddish-orange. The fur is distributed with varying densities throughout the body: the genital region (scrotum and pubic zone), axilla, and the base of the tail have lower densities, while the forward region is much higher. Many individuals have stripes or whorls of fur of striking coloration on their throats. The cotton-top also has whiskers on its forehead and around its mouth.^[11]

 

Habitat and distribution

A sign in Tayrona National Natural Park in northern Colombia pointing out the tamarin's endangered status in the only part of the world where it still exists

The cotton-top tamarin is restricted to a small area of northwest Colombia, between the Cauca and Magdalena Rivers to the south and east, the Atlantic coast to the north, and the Atrato River to the west. They are found exclusively in Colombia; 98% of their habitat has been destroyed. Historically, the entire area was suitable for the cotton-top tamarin, but due to habitat loss through deforestation, it survives in fragmented parks and reserves. One of the most important areas for the cotton-top is the Paramillo National Park, which consists of 460,000 hectares (1,800 sq mi) of primary and secondary forests.^[2]

The cotton-top tamarin is found in both primary and secondary forests, from humid tropical forests in the south of its range to tropical dry forests in the north. It is seldom found at altitudes above 400 m (1,300 ft), but has been encountered up to 1,500 m (4,900 ft).^[2][9] It prefers the lower levels of the tropical forests, but may also be found foraging on the ground and between the understory and the canopy. It can adapt to forest fragments and can survive in relatively disturbed habitats. In the dry forests are pronounced seasons. Between December and April, it is dry, while heavy rainfall occurs between August and November which can flood the forest floor. Across its range, annual rainfall varies between 500 and 1,300 mm (20 and 51 in).^[4]

 

 

Ecology

 

The cotton-top tamarin has a diet of mainly fruit (40%) and animal material (40%).^[14] This includes insects, plant exudates such as gum and sap, nectar, and occasionally reptiles and amphibians. Due to its small body size and high food passage rate, its diet must be high-quality and high-energy. Insectivory is common in the cotton-top and the species hunts for insects using a variety of methods: stealth, pouncing, chasing, exploring holes, and turning over leaves.^[13]

Tamarins act as seed dispersers in tropical ecosystems. While larger primates eat larger seeds, tamarins eat the smaller ones. The expelled seeds have a higher germination rate than others and ingesting larger seeds may help to dislodge and expel intestinal parasites.^[4]

The cotton-top tamarin is diurnal and sleeps with its social group in trees with foliage cover. The group leaves the sleeping tree together an hour after dawn and spends the day foraging, resting, travelling, and grooming.^[4][15] The species is thought to rise late and increases the speed of its foraging and travelling before dusk to avoid crepuscular and nocturnal predators. Its main predators include raptors, mustelids, felids, and snakes.^[16][17] The cotton-top tamarin is extremely vigilant, always looking for potential predators. When the group is resting, one individual moves apart and acts as a lookout to alert the group if it sees a threat.^[4]

The cotton-top tamarin can live as long as 24 years in captivity, while its lifespan in the wild averages 13 years.^[4]

Behavior

Play media

Two cotton-top tamarins feed at Ueno Zoo, in Japan (video)

Social systems

The cotton-top tamarin is a highly social primate that typically lives in groups of two to nine individuals, but may reach up to 13 members.^[2][15][18] These small familial groups tend to fluctuate in size and in composition of individuals and a clear dominance hierarchy is always present within a party. At the head of the group is the breeding pair. The male and female in this pair are typically in a monogamous reproductive relationship, and together serve as the group's dominant leaders.^[18]

Dominant pairs are the only breeding pair within their groups, and the female generally has authority over the breeding male. While nonbreeding group members can be the leading pair's offspring, immigrant adults may also live with and cooperate in these groups. This social grouping in cotton-top tamarins is hypothesized to arise from predation pressure.^[19] Cotton-top tamarins exhibit prosocial behavior that benefits other members of the group,^[20] and are well known for engaging in cooperative breeding whereby the group's subordinate adults help in rearing the offspring of the dominant pair. The dominant female is more likely to give birth to non-identical twins than a singleton, so it would be too energetically expensive for just one pair to raise the young.^[21]

To prevent younger, subordinate females within the group from breeding, the dominant female uses pheromones. This suppresses sexual behavior and delays puberty.^[22][23] Unrelated males that join the group can release the females from this reproductive suppression; this may result in more than one female of the group becoming pregnant, but only one of the pregnancies will be successful.^[24]

 

 

Cooperation

A male grooming a female as part of the species' cooperative ritual

In cooperative breeding, the effort put into caring for the dominant breeders' offspring is shared by the group members. Parents, siblings, and immigrant adults share young rearing duties for the breeding pair's young. These duties include carrying, protecting, feeding, comforting, and even engaging in play behavior with the group's young. Cotton-top tamarins display high levels of parental investment during infant care. Males, particularly those that are paternal, show greater involvement in caregiving than do females.^[25] Despite this, both male and female infants prefers contact and proximity to their mothers over their fathers.^[25] Males may invest additional support in rearing offspring as a form of courtship to win the favor of the group's dominant female. However, evidence indicates that time spent carrying infants does not correlate with a male's overall copulation frequency.^[26]

Since only one female in a group breeds, heavy investment in infant care ensures that all offspring survive until independence. Accordingly, cotton-top tamarins bear excessive costs to care for the group's young.^[26][27] Male carriers, especially paternal carriers, incur large energetic costs for the sake of the group's young. This burden may cause some male cotton-tops to lose up to 10–11% of their total body weight.^[28] The large weight loss may occur from reduced food intake as infant-carrying inhibits foraging ability for a carrier. The trend of male-carrier weight loss and decreased food intake is in contrast to the dominant female's periovulatory period, when she gains weight after increasing her own food intake and relinquishing much of her infant-carrying duties.^[27]

 

 

Altruism

 

 

While caregiving by males appears to be altruistic, particularly in cotton-top sires, the costs of infant care may in fact be tolerated for selfish reasons. Namely, the costs to male weight and foraging ability may, in turn, promote consecutive pregnancies in dominant females, thereby providing more offspring bearing the sire's genes.^[27] Additionally, the cooperative breeding structure of cotton-tops can change with group size and parental experience. First-time sires spend a greater amount of time carrying the infant than experienced ones, and in smaller groups, sires do a greater proportion of carrying and feeding the infant than in larger groups, where helpers take on more of the work. Total care for infants remains constant with varying group size, and infant outcome is not significantly different in groups that have differing levels of experience in raising offspring.^[29]

Once infants reach sufficient age, they permanently leave the backs of their carriers and begin contributing to the group.

The cooperative breeding hypothesis predicts that cotton-top tamarins engage with this young-rearing paradigm, and in turn, naturally embrace patterns of prosocial behavior.^[20] These monkeys engage in such behavior by acting altruistically within their groups in caring for infants, vocalizing alarm calls, and in sharing food. Though some studies indicate that cotton-top tamarins have the psychological capacity to participate in reciprocally mediated altruism,^[30] it is unclear whether the cotton-top tamarin acts solely using judgments on reinforcement history.^[31]

Other studies involving cotton-top tamarins have hinted that positive reciprocity and reciprocal altruism are irrelevant in the prosociality of these primates.^[20] Some researchers believe these primates tend to cooperate for selfish reasons and in situations where they incur some benefit for themselves. That is, cooperation in cotton-top tamarins can be better described by mutualism than by true altruism.^[31]

Tamarins in captivity have shown the ability to distinguish other individuals based on cooperative tendencies and past behavior. Cotton-tops ultimately use this information to guide future cooperation. Brief periods of defection tend to cause swift, irreparable breakups between these primates and their cooperators. To avoid this, cotton-top tamarins may make economically-driven decisions based on the projected incentives of a potential cooperator.^[31]

Spite and aggression

Despite an expansive array of altruistic behaviors, cotton-top tamarins engage in great bouts of spite through negative reciprocity and punishment. They have been observed to immediately start denying cooperation with monkeys that deny them benefits.^[31] Further, in captivity, these primates are not observed to increase altruistic behavior with fellow primates that are committed fully to cooperation. Based on this, researchers believe that repeated interactions in a cooperative society like that of the cotton-top tamarin can heighten the chances that an individual will designate behavioral punishments to others in its group.^[32] This reaction has also been observed in other species.^[33] However, these reciprocal punishments, or relative lack of altruistic actions, may alternatively happen as a result of response facilitation that increases the chances of a cotton-top punishing another primate after watching that individual perform a similar action.^[34]

Dominant females may evict subordinate females from the group out of spite.

Another way to look at punishment in cotton-top tamarins is by observing their aggressive behavioral responses within and between groups, as well as between species. The cotton-top tamarin, like many marmosets, other tamarins, and specifically those in the genus Saguinus, stages aggressive displays almost exclusively towards fellow monkeys that belong to the same gender.^[35] These intrasexual displays of aggression are more frequent in females, and are vital when a breeding female is forcing both subadult and adult females to emigrate out of a familial group.^[15]

Though aggression can occur within groups, the response towards intruders of another species is much more drastic and can involve a sexual dimorphism in displays. Females typically employ scent-marking intruder response tactics, whereas males are more prone to vocalizing threats, physical aggression, and piloerection.^[36] Scent-marking in cotton-top tamarins is done in two ways: either using anogenital scent-marking, or suprapubic scent-marking. The ability to use both of these separate glandular fields for threat signals may indicate females have developed diverging evolutionary threats through differential use of these markings.^[36] These variable signals may be used to sign a territorial encounter, or serve as a reproductive signal. The intensity of female threats is generally comparable when directed at intruders of either gender. In contrast, male cotton-tops are considerably more threatening towards fellow males than towards females.^[36]

 

 

Communication

 

 

The cotton-top tamarin vocalizes with bird-like whistles, soft chirping sounds, high-pitched trilling, and staccato calls. Researchers describe its repertoire of 38 distinct sounds as unusually sophisticated, conforming to grammatical rules. Jayne Cleveland and Charles Snowdon performed an in-depth feature analysis to classify the cotton-top's repertoire of vocalizations in 1982. They concluded that it uses a simple grammar consisting of eight phonetic variations of short, frequency-modulated "chirps"—each representing varying messages—and five longer constant frequency "whistles". They hypothesize that some of these calls demonstrate that the cotton-top tamarin uses phonetic syntax, while other calls may be exemplars of lexical syntax usage.^[37] Each type of call is given a letter signifier; for example, C-calls are associated with finding food and D-calls are associated with eating.^[38] Further, these calls can be modified to better deliver information relevant to auditory localization in call-recipients.^[37] Using this range of vocalizations, the adults may be able to communicate with one another about intention, thought processes, and emotion, including curiosity, fear, dismay, playfulness, warnings, joy, and calls to young.^[39]

 

 

Language acquisition

 

 

Over the first 20 weeks, after a cotton-top tamarin is born, it is not fully capable of producing the range of vocalizations that an adult monkey can. Despite this limitation on speech producibility, researchers believe that language acquisition occurs early on with speech comprehension abilities arising first.^[38] Infants can at times produce adult-like chirps, but this is rarely done in the correct context and remains inconsistent across the first 20 weeks of life. Regardless, infant cotton-tops are able to respond in behaviorally appropriate ways to varying contexts when presented with adult chirps. This indicates that verbal perception is a quickly acquired skill for offspring, followed closely by auditory comprehension, and later by proper vocal producibility.^[38]

Although limited in their own vocal ranges, juvenile cotton-tops respond appropriately to varying contexts provided by adult vocalizations.

Castro and Snowdon (2000) observed that aside from inconsistent adult-like chirping, cotton-top infants most often produce a prototype chirp that differs in vocalization structure from anything seen in the full adult range of vocalizations. Infants are thought to imitate adult speakers, which use differing calls in various contexts, but by using solely the infant prototypical chirp. For instance, adult cotton-tops are known to significantly reduce the amount of general alarm calling in the presence of infants.^[37] This is likely adapted so that adults in close proximity to the groups young do not attract the attention of predators to infant-dense areas. Additionally, infants reduce their prototype chirping in the presence of predators. Whether infants are shadowing the calling behavior of adults or they are comprehending danger remains unclear. However, researchers argue that young cotton-top tamarins are able to represent semantic information regardless of immature speech production.^[38]

To confirm the notion that language acquisition occurs as a progression of comprehension before production, Castro and Snowdon (2000) showed that infants respond behaviorally to vocalizing adults in a fashion that indicates they can comprehend auditory inputs. When an adult produces a C-call chirp, used to indicate food preference and when navigating to a food source, an infant approaches the adult caller to be fed, but do not use the prototype calling as a proxy for C-calls.^[38] This finding argues for the idea that infants are able to understand vocalizations first, and later acquire the ability to communicate with adult vocalizations.

 

 

General calling

 

Among the typical cotton-top tamarin communicative vocalizations, the combination long call (CLC) and the alarm call (AC) are the most heavily represented in the literature. CLCs encompass a range of contact calls that are produced by isolated individuals using chirps and whistles.^[37][40] This type of call is also used for seemingly altruistic alarm calls, thus adding to its range of cooperative behaviors. It is issued in the presence of kin when a threatening llamas predator is seen. Predators of the cotton-top tamarin include snakes, ocelots, tayras, and most notably, hawks.^[19] Early observations by Patricia Neyman even showed that cotton-tops produce diverse sets of alarm calls that can discriminate the presence of birds of prey versus ground-based predators.^[15]

A mature cotton-top tamarin producing vocalization for group mates

CLCs involve the production of complex sequence multisyllabic vocalizations. Researchers have argued that long calls exhibit individual differences, thus can carry information sufficient for recipients to determine caller identity. Using habituation-discrimination paradigms in language experiments, this theory has been confirmed multiple times in literature.^[40][41] However, the individual syllables within a complete CLC vocalization in isolation of each other do not transfer sufficient information to communicate messages between monkeys. Scientists thus consider the whole, intact string of vocalizations to be the unit of perception for CLCs in the cotton-top tamarin.^[42] These examinations may confirm that cotton-tops incorporate a lexical syntax in areas of their communication.

Since tamarins can discriminate between predatory threats using varying vocalizations, recipients of an AC are thought to extract various complex signals from this form of communication. Primarily, cotton-tops are able to glean the identity of the cooperating tamarin through differences in individuals' alarm calls.^[19] Further, adults are able to discriminate the gender of callers from their ACs and determine the range of calls within a related tamarin's alarm calling repertoire.^[19] Alarm call-based identification is postulated to play a number of functional roles in the cotton-top tamarin. Firstly, an AC recipient is able to identify a cooperating tamarin, and by recognizing which in their group it is, be able to judge the reliability of the AC from past experience. This may arise from a selective pressure for being able to statistically determine the amount of risk present, and how endangered an individual and its group are.^[19]

Additionally, being able to localize auditory signals may help determine predator location, especially in the presence of a second AC from a different tamarin in the group. This can help confirm predator presence, type (e.g. flying versus ground-based), and support the recipient in triangulating a predator's location. In the context of the cotton-top's cooperative breeding groups, this is postulated as being adaptive for determining the variable risk to one's group members.^[19] For example, a call recipient is able to determine which of its kin are and are not at risk (e.g. young offspring, mates, subordinates, relatives, carriers, etc.) and plan subsequent actions accordingly.

Food calls

The species is thought to vocalize food preference using C-calls and food retrieval and eating using D-calls.

The cotton-top tamarin makes selective, specialized vocalizations in the presence of food.^[43] These include the C-call, produced when a cotton-top approaches and sorts through food, and the D-call, which is associated with food retrieval and is exhibited while eating.^[37]

C-call chirping is believed to be an honest signal for communicating food preference, and a cotton-top tamarin more often and more rapidly vocalizes with these chirps when approaching a highly favored food source. Functionally, this behavior may inform other tamarins of the actions the caller will take in a feeding context and whether a preferable food source is available.^[43] Despite this research indicating that food calls may be informative to fellow group mates, other observations of cotton-tops show that quantity and distribution of food and audience do not significantly alter a caller's food-centered vocalizations.^[44]

The cotton-top tamarin is seen to produce food calls both in the presence and absence of group members.^[44] Additionally, response to food calls are directed back to an original caller independent of visual confirmation of a food source. While this may appear to be a result of a very primitive form of communication, Roush and Snowdon (2005) maintain that the food-calling behavior confers some mentally representable information about food to recipient tamarins.

 

 

Conservation status

 

 

The wild population is estimated at 6,000 individuals, with 2,000 adults.^[2] This species is critically endangered, and was listed in "The World's 25 Most Endangered Primates between 2008 and 2012."^[45] The publication lists highly endangered primate species and is released every two years by the International Union for Conservation of Nature Species Survival Commission Primate Specialist Group. The cotton-top tamarin was not selected for the 2012–2014 publication.^[46]

The species is critically endangered, with a wild population of merely 6,000 individuals including about 2,000 free-roaming adults.

Habitat destruction through forest clearing is the main cause of this collapse, and the cotton-top has lost more than three-quarters of its original habitat to deforestation,^[2] while the lowland forest in which it lives has been reduced to 5% of its historical range. This land is then used for large-scale agricultural production (i.e. cattle) and farming, logging, oil palm plantations, and hydroelectric projects that fragment the cotton-top tamarin's natural range.^[47]

The illegal pet trade and scientific research have also been cited as factors by the IUCN. While biomedical studies have recently limited their use of this species, illegal capture for the pet trade still plays a major role in endangering the cotton-top. Before 1976, when CITES listed the species under Appendix I banning all international trade, the cotton-top tamarin was exported for use in biomedical research.

In captivity, the cotton-top is highly prone to colitis, which is linked to an increased risk of a certain type of colon cancer. Up to 40,000 individuals were caught and exported for research into those diseases, as well as Epstein-Barr virus, for the benefit of humans. The species is now protected by international law. Although enough individuals are in captivity to sustain the species, it is still critically endangered in the wild.^[47]

The Proyecto Tití ("Project Tamarin")^[48] was started in 1985 to provide information and support in conservation of the cotton-top tamarin and its habitat in northern Colombia. Proyecto Tití's programs combine field research, education, and community programs to spread awareness about this endangered species and encourage the public to participate in its protection. It now has partner status with the Wildlife Conservation Network.^[49]

In January 2015, two captive cotton-top tamarins at the Alexandria Zoological Park in Alexandria, Louisiana, died when a caretaker left them outside overnight in temperatures as low as 30 °F. One other individual survived.^[50][51]

 

 Binomial name

 

 Saguinus oedipus

(Linnaeus, 1758)

 

 

^{Geographic range}  

  

 

 

 

THE GOLDEN LION TAMARIN

 

The golden lion tamarin (Leontopithecus rosalia, Portuguese: mico-leão-dourado [ˈmiku leˈɐ̃w̃ dowˈɾadu], [liˈɐ̃w̃ doˈɾadu]), also known as the golden marmoset, is a small New World monkey of the family Callitrichidae. Native to the Atlantic coastal forests of Brazil, the golden lion tamarin is an endangered species.^[4] The range for wild individuals is spread across four places along southeastern Brazil, with a recent census estimating 3,200 individuals left in the wild^[5] and a captive population maintaining about 490 individuals among 150 zoos.^[3][6][7]

 

 

 

Physical characteristics

Closeup on the golden lion tamarin's face

The golden lion tamarin gets its name from its bright reddish orange pelage and the extra long hairs around the face and ears which give it a distinctive mane.^[8] Its face is dark and hairless. The bright orange fur of this species does not contain carotenoids, which commonly produce bright orange colors in nature.^[9] The golden lion tamarin is the largest of the callitrichines. It is typically around 261 mm (10.3 in) and weighs around 620 g (1.37 lb). There is almost no size difference between males and females. As with all New World monkeys, the golden lion tamarin has tegulae, which are claw-like nails, instead of ungulae or flat nails found in all other primates, including humans.^[10] Tegulae enable tamarins to cling to the sides of tree trunks. It may also move quadrupedally along the small branches, whether through walking, running, leaping or bounding.^[11] This gives it a locomotion more similar to squirrels than primates.

 

 

Habitat and distribution

 

 

The Golden Lion Tamarin has a very limited distribution range, as over time they have lost all but 2%–5% of their original habitat in Brazil.^[12] Today, this tamarin is confined to three small areas of the tropical rain forest in southeastern Brazil: Poço das Antas Biological Reserve, Fazenda União Biological Reserve, private land through the Reintroduction Program.^[6] The first population estimate made in 1972 approximated the count at between 400 and 500. By 1981 the population was reduced to less than 200. Surveys from as recently as 1995 suggested that there may only have been at most 400 golden lion tamarins left in the wild; they have made a nice comeback and now number 3200 in the wild. Tamarins live along the far southeast border of the country in the municipalities of Silva Jardim, Cabo Frio, Saquarema, and Araruama.^[13] However, they have been successfully reintroduced to the municipalities of Rio das Ostras, Rio Bonito, and Casimiro de Abreu.^[14] Tamarins live in coastal lowland forests less than 300 m (984 ft) above sea level.^[15] They can be found in hilltop forests and swamp forests.

 

 

Behaviour and ecology

 

The golden lion tamarin is active for a maximum of 12 hours daily. It uses different sleeping dens each day.^[16][17] By frequently moving their sleeping nests around, groups minimize the scent left behind, reducing the likelihood of predators finding them.^[18] The first activities of the day are traveling and feeding on fruits. As the afternoon nears, tamarins focus more on insects. By late afternoon, they move to their night dens. Tamarin groups use hollow tree cavities, dense vines or epiphytes as sleeping sites. Sites that are between 11 and 15 m (36 and 49 ft) off the ground are preferred. The golden lion tamarin tends to be active earlier and retire later in the warmer, wetter times of the years as the days are longer.^[16] During drier times, it forages for insects longer as they become more scarce.^[16][17]

Golden lion tamarins are characterized by using manipulative foraging under tree barks and epiphytic bromeliads. Their sites of foraging are usually distributed around their home ranges, which are large territories (averaging 123 hectares) in which multiple foraging sites are located, to find sufficient resources over long periods of time. These areas are sufficient enough in size so that even if there is overlap in between the home range of two different groups, the interactions are minimal due to the distribution of the foraging sites (they spend 50% of their time in approximately 11% of their home range).^[19]

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Leontopithecus rosalia in Singapore Zoo

The golden lion tamarin has a diverse, omnivorous diet consisting of fruits, flowers, nectar, bird eggs, insects and small vertebrates. They rely on microhabitats for foraging and other daily activities and tamarins will use bromeliads, palm crowns, palm leaf sheaths, woody crevices, lianas, vine tangles, tree bark, rotten logs, and leaf litters.^[16][17] The golden lion tamarin uses its fingers to extract prey from crevices, under leaves, and in dense growth; a behavior known as micromanipulation.^[20] It is made possible by elongated hands and fingers. Insects make up to 10–15% of its diet. Much of the rest is made of small, sweet, pulpy fruits. During the rainy season, the golden lion tamarin mainly eats fruit, however during drier times, it must eat more of other foods like nectar and gums.^[16] Small vertebrates are also consumed more at these times as insects become less abundant.

 

 

Social structure

Family groups may consist of up to eight members.

Golden lion tamarins are social and groups typically consist of 2-8 members. These groups usually consist of one breeding adult male and female but may also have 2–3 males and one female or the reverse.^[21] Other members include subadults, juveniles and infants of either sex. These individuals are typically the offspring of the adults. When there is more than one breeding adult in a group, one is usually dominant over the other and this is maintained through aggressive behavior. The dominance relationship between males and females depends on longevity in the group. A newly immigrated male is subordinate to the resident adult female who inherited her rank from her mother.^[22] Both males and females may leave their natal group at the age of four, however females may replace their mothers as the breeding adult, if they die, which will lead to the dispersal of the breeding male who is likely her father. This does not happen with males and their fathers. Dispersing males join groups with other males and remain in them until they find an opportunity to immigrate to a new group. The vast majority of recruits to groups are males.^[23] A male may find an opportunity to enter into a group when the resident male dies or disappears. Males may also aggressively displace resident males from their group; this is usually done by two immigrant males who are likely brothers. When this happens, only one of the new males will be able to breed and will suppress the reproduction of the other. A resident male may also leave a vacancy when his daughter becomes the breeding female and he must disperse to avoid inbreeding.^[24] Golden lion tamarins are highly territorial and groups will defend their home range boundaries and resources from other groups.^[25]

Tamarins emit "whine" and "peep" calls, which are associated with alarm and alliances respectively.^[26] "Clucks" are made during foraging trips or during aggressive encounters, whether directed at conspecifics or predators.^[27] "Trills" are used to communicate over long distances to give away an individual's position. "Rasps" or "screeches" are usually associated with playful behavior. Tamarins communicate though chemicals marked throughout their territories. Reproductive males and females scent mark the most and their non-reproductive counterparts rarely do so. Dominant males use scent marking to show their social status and may suppress the reproductive abilities of the other males.

 

 

Reproduction

The mother provides transportation at the early stages of the infant's life.

The mating system of the golden lion tamarin is largely monogamous. When there are two adult males in a group only one of them will mate with the female. There are cases of a male mating with two females, usually a mother and daughter.^[21] Reproduction is seasonal and depends on rainfall. Mating is at its highest at the end of the rainy season between late March to mid-June and births peak during the September–February rains.^[28] Females are sexually mature between of 15–20 months but it isn't until they are 30 months old when they can reproduce.^[27] Only dominant females can reproduce and will suppress the reproduction of the other females in the group.^[29] Males may reach puberty by 28 months.^[28] Tamarins have a four-month gestation period. Golden lion tamarin groups exhibit cooperative rearing of the infants. This is due to the fact that tamarins commonly give birth to twins and, to a lesser extent, triplets and quadruplets. A mother is not able to provide for her litter and needs the help of the other members of the group.^[30] The younger members of the groups may lose breeding opportunities but they gain parental experience in helping to rear their younger siblings.^[22] In their first 4 weeks, the infants are completely dependent on their mother for nursing and carrying. By week five, the infants spend less time on their mother’s back and begin to explore their surroundings. Young reach their juvenile stage at 17 weeks and will socialize other group members. The sub-adult phase is reached at 14 months and a tamarin first displays adult behaviors.

Ecosystem roles

Vocalizing.

The golden lion tamarin has a mutualistic interaction with 96 species of plants found in the Atlantic Forest. This interaction is based on seed dispersal and food sources for the tamarins. The tamarins show repeat visits to those plants with abundant resources. They tend to move around their territories, and therefore, seeds are dispersed to areas far from the parent shadow, which is ideal for germination. Their seed distribution is important to forest regeneration, and genetic variability and survival of endangered plant species.^[31]

Predation

 

 

A study has shown that increased predation has caused significant decreases in the population numbers.^[32] A survey conducted in 1992 found the number of wild population of golden lion tamarins to be 562 individuals in 109 groups. Currently, the average group size includes 3.6 to 5.7 individuals and densities from 0.39 groups/km to 2.35 groups/km.^[33] These predatory attacks occur at the golden lion tamarin sleeping sites. The predators make those sleeping sites, which are mainly tree holes (about 63.6%), larger in order to attack the golden lion tamarins, sometimes wiping out the entire family. The preferred sleeping sites of most golden lion tamarins are tree holes in living trees next to other larger trees with a small percentage of canopy cover. These sleeping sites not only provide a place for sleep, but also offer protection and easy access to foraging sites. Most of the tree holes are lower to the ground, so they are easier to enter. Tree holes that are located in living trees are drier, warmer, and have a lower number of insects and therefore a decreased percentage of transmitted diseases. A smaller percentage of canopy coverage allows the golden lion tamarins to detect the predators faster, and being surrounded by other large trees allows them access to escape routes.^[32] Due to degradation of their habitats, there are fewer trees that can support entire social groups and some have to resort to using bamboo (17.5%), vine tangles (9.6%), and bromeliads (4.7%) as a sleeping site, making them more susceptible to predators. Golden lion tamarins are known to use different den sites, but do not change sites often. They are more likely to reuse secure sites that will offer protection. However, the disadvantage of doing so is that predators are able to learn where these sites are located. Golden lion tamarins also scent mark their den holes, so they can quickly return to them in the afternoon time when predators are most active. While excessive scent makes it easier for golden lion tamarins to find their sleeping sites, it also helps predators locate their prey. Moreover, increased deforestation has decreased habitat space, providing predators easy access to their prey, causing a decline in the golden lion tamarin population.^[34]

 

 

Conservation

Aerial view of Poço das Antas Biological Reserve.

Threats to the golden lion tamarin population include illegal logging, poaching, mining, urbanization, deforestation, pet trading,^[35] and infrastructure development and the introduction of alien species. In 1969, the number of individuals in the Atlantic Forest was found to have dropped to a low of 150 individuals.^[36] In 1975 the golden lion tamarin was listed under Appendix I of CITES, given to animals threatened with extinction that may be or are being affected by trade.^[37] The species was listed as Endangered by the IUCN in 1982,^[3] and by 1984 the National Zoological Park in Washington, D.C. and the World Wide Fund for Nature, through the Golden Lion Tamarin Association, began a reintroduction programme from 140 zoos worldwide.^[36] Despite the success of the project, the IUCN classification rose to Critically Endangered in 1996.^[3] By 2003 the successful establishment of a new population at União Biological Reserve enabled downgrading the species to endangered,^[38] but the IUCN warns that extreme habitat fragmentation from deforestation means the wild population has little potential for any further expansion.^[3] In an attempt to curb the golden lion tamarin's precipitous decline, several conservation programs have been undertaken. The intent is to strengthen the wild population and maintain a secure captive population in zoos worldwide. The survival rate of re-introduced animals has been encouraging, but destruction of unprotected habitat continues.

Reintroduction

Because of the extensive habitat loss of the golden lion tamarin, the wild population reached endangered status in the early 1980s. Beginning in 1983, there has been a huge effort on behalf of scientists and conservationists to reintroduce captive-born golden lion tamarins back into the wild. With the help of the Brazilian government, conservationists established the Poço das Antas Biological Reserve and the União Biological Reserve as sites for reintroduction. The goals of the reintroduction process include increasing the size as well as the genetic diversity of the wild population, increasing the available range to better encompass the historic range of the tamarins in Brazil, and widening the scope of public awareness and education programs.^[39]

The first step of reintroduction begins with zoo free ranging programs, where tamarins have access to explore the entire zoo. However, they are kept on zoo grounds by the presence of a nest box, an ice box like container where their food is kept. When the tamarins are reintroduced in Poço das Antas Biological Reserve, they require a large amount of post-release training and veterinary care. For the first 6–18 months the reintroduced groups are monitored. Additionally, 1-2 tamarins from each group are radio collared to allow careful monitoring, and all reintroduced tamarins are tattooed and dye marked for easy identification.^[39]

Translocation

Secondly, in an effort to save the golden lion tamarins from extinction, some of the golden lion tamarins have been removed from small, isolated unsafe forests and placed into a larger, protected forest; specifically they were moved to União Biological Reserve and Poço das Antas reserve. This effort to move the golden lion tamarins into União Biological Reserve in Brazil began in 1991.^[40] The golden lion tamarins faced the potential of getting new diseases that they had not been previously exposed to. Many were exposed to callitrichid hepatitis, and contracted the disease.^[41]

Despite the challenge of illness, the forty-two translocated golden lion tamarins' population grew to over 200 in União Biological Reserve. The number of wild golden lion tamarins is now up in the thousands in all reserves and ranches combined in Brazil. These numbers were once down in the 200s in 1991. By 2025, the number of golden lion tamarins that are protected is projected to be greater than 2000.^[40]

 

 

Effects of habitat loss

 

 

Golden lion tamarins are native to the Atlantic Forest of Brazil. Their original habitat was located from the southern part of the state of Rio de Janeiro to the southern part of the state of Espirito Santo. However, deforestation of Atlantic Forest for commercial purposes, predation, and capture of the golden lion tamarins for animal trade and sale as pets has limited their population to about five municipalities across Rio de Janeiro. Most of the population is now found in the Poco des Antas Biological Reserve in Rio de Janeiro.^[33]

However, due to the deforestation and fragmentation of the Atlantic forest, their home ranges have decreased in size.^[19] The decrease in size has been reported in terms of fragmentation, and today the forest consists of thousands of fragments equaling only 8% of its former size.^[42] This directly affects their areas of foraging and subsequently, the amount of resources available.^[19]

 

 

Effect on juvenile behavior

 

The habitat of the tamarins also affects their behavior and social interactions. For example, the type of trees present has a significant effect on the behavior of juvenile golden lion tamarins. Their juvenile behavior is characterized by social play between individuals of different ages and species. This is a key aspect of their social, cognitive and motor skill development, and it influences their behavior when facing competition and predators; how they play mirrors the way they act when facing predatory or competitive interactions. Social play is observed more in large branches (>10 cm) and vine tangles (4m above ground), which is considered safe for them, as they are less vulnerable to predators, compared to play in the dangerous areas including canopy branches and the forest floor. Therefore, deforestation affects the diversity in the forest and decreases the "safe" areas for play for the juvenile tamarins. As a result, play decreases and therefore the development of learned survivorship behaviors does as well. Also, if play is observed in the dangerous areas, the individuals are more exposed to predators, leading to a population decline; which resembles the effect of predation on their sleeping sites. The exposure to predation not only affects the juvenile tamarins but the adults as well, since it has been observed that play happens in the center of the group for protection of the young.^[43]

 

 

Increase in inbreeding

 

Additionally, this deforestation and fragmentation also leads to demographic instabilities, and an increased probability of inbreeding, consequently leading to inbreeding depression and a population decline.^[44] In the case of inbreeding, the problem lies in the increase of the isolated fragments where golden lion tamarins live. Inbreeding leads to low levels of genetic diversity and has a negative effect on survivorship; inbred offspring have a lower survivorship than non-inbred offspring. Fragmentation leads to a decline in dispersal and as a result, a decline in breeding with individuals of other groups. Consequently, inbreeding depression is observed in these populations.^[45] With delay breeding, the decrease and shortage of territory puts pressure on golden lion tamarins to disperse in order to find necessary resources and areas suitable for their survival. However, dispersal is risky and requires a lot of energy that could have been used for reproduction instead.^[46]

 Binomial name

 

 Leontopithecus rosalia

(Linnaeus, 1766)