Cotton-top tamarin

Appearance

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



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. 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 hairs covering its face, but they are so fine as to appear naked, thus is considered a bare-faced tamarin. Its lower canine teeth are longer than its incisors, creating the appearance of tusks. Like other callitrichids, the cotton-top tamarin has two molar teeth on each side of its jaw, not three like other New World monkeys.

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 , 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.

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. In Spanish, it is commonly called ''bichichi, tití pielroja, "tití blanco, tití cabeza blanca'', or ''tití leoncito''. In German-speaking areas, the cotton-top tamarin is commonly known as ''Lisztaffe'' most likely due to the resemblance of its crest to the hairstyle of Hungarian composer and piano virtuoso Franz Liszt.

The species was first described by Linnaeus in 1758 as ''Simia oedipus''. Linnaeus chose the species name ''oedipus'', which means ''swollen foot'', but as the species does not have particularly large feet, it is unknown why he chose this name. 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''. Subsequent analyses by Hernández-Camacho and Cooper , Mittermeier and Coimbra-Filho , and later Grooves consider the ''S. oedipus'' and ''S. geoffroyi'' types to be separate species.

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

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. 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.

Distribution

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 mostly live Brazil; two-thirds 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 of primary and secondary forests.

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 , but has been encountered up to 1,500 m . 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 .

Status

The wild population is estimated at 6,000 individuals, with 2,000 adults. This species is critically endangered, and was listed in "The World's 25 Most Endangered Primates between 2008 and 2012." 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.



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, 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 and farming, logging, oil palm plantations, and hydroelectric projects that fragment the cotton-top tamarin's natural range.

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.

The Proyecto Tití 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.

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.

Behavior

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. 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.

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. Cotton-top tamarins exhibit prosocial behavior that benefits other members of the group, 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 nonidentical twins than a singleton, so it would be too energetically expensive for just one pair to raise the young.

To prevent younger, subordinate females within the group from breeding, the dominant female uses pheromones. This suppresses sexual behavior and delays puberty. 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.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. 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. Further, these calls can be modified to better deliver information relevant to auditory localization in call-recipients. 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.

Habitat

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 mostly live Brazil; two-thirds 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 of primary and secondary forests.

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 , but has been encountered up to 1,500 m . 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 .The cotton-top tamarin has a diet of mainly fruit and animal material . 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.

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.

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. 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. 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.

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

Food

The cotton-top tamarin makes selective, specialized vocalizations in the presence of food. 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.

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. 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.

The cotton-top tamarin is seen to produce food calls both in the presence and absence of group members. 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 from a very primitive form of communication, Roush and Snowdon maintain that the food-calling behavior confers some mentally representable information about food to recipient tamarins.