I  Natural History

• Cotton-top tamarins are small monkeys weighing between 400-700g and are approximately 23.07cm long (including tail).
• The cotton-top tamarin is a highly endangered species, endemic to the northwest region of Colombia.
• Major threats to the cotton-top tamarin’s existence in the wild include , but are not limited to, habitat destruction, hunting, and live capture.
• The cotton-top tamarin has been an important model for the biomedical research since it is the only primate that spontaneously develops colonic adenocarcinoma in captivity.

 

Introduction

    Although the cotton-top tamarin is abundant in captivity with populations found in both zoos and research institutions throughout the world (Tardif, 1989), it is one of the most endangered primates in its native habitat of Colombia. Found only in northwestern Colombia, the cotton-top tamarin is continually threatened by the destruction of its habitat, live capture for local and international pet markets and the biomedical industry (Mast & Patiiio, 1988). During the late 1960's and early 1970's between 20,000-40,000 cotton-top tamarins were imported into the U.S. for use in biomedical research (Hernandez Camacho & Cooper, 1976). In 1973, the species was declared endangered and exportation was banned. The cotton-top tamarin is one of the most important primate models for biomedical research and has been used in studies from Epstein-Barr virus to colitis and colon cancer. However, it's primary use in the biomedical community has been the study of colon adenocarcinoma, as it is the only primate model which, like humans, spontaneously develops colitis and/or colon cancer (Clapp, 1993).

The cotton-top tamarin is just one of the many endangered species found in the country of Colombia. Highlighting such an important species in education and public awareness campaigns can generate support for the conservation of Colombia's natural resources.

Taxonomy

The Callitrichidae comprise the most diverse family of New World monkeys, with 32 species. Callitrichids are the smallest of the New World monkeys, have nonprehensile tails, possess claws instead of nails, and move quadrupedally (Hershkovitz, 1977). All callitrichids lack a set of paired molars that are typically present in other New World primate species. In addition, Callithrix and Cebuella can be distinguished on the basis of dentition from Saguinus and Leontopithecus. Only Callithrix and Cebuella have "short tusked" lower anterior dentition allowing them to perforate tree bark and induce the flow of exudates (gum and sap) which are important food sources. In contrast, Saguinus and Leontopithecus have the "long-tusked" dental configuration in which the canines are much longer than the incisors.

Of the 12 tamarin species within the genus Saguinus (NEttermeier et al., 1992; Mittermeier & Coimbra-Filho, 1981), Snowdon and Soini (1988) have divided the tamarins into two groups, the Hylaen (or Amazonian) and the extra-Amazonian. The latter group of trans-Andean tamarins comprise three taxa (S. geoffroyi, S. oedipus, and S. leucopus), all of which are found in Colombia.

There has been considerably discrepancy regarding the taxonomy of S. oedipus and S. geoffroyi. Hershkovitz (1977) describes both the cotton-top tamarin and the Panamanian tamarin as subspecies of Saguinus oedipus (S. o. oedipus and S. o. geoffroyi respectively), and Hernandez Camacho and Defler (1983; 1985) have also suggested that these two taxa fall beneath a single superspecies. However, reports by Skinner (1991) and Rosenberger (1992) have suggested the more widely accepted view that both of these taxa are full species (see Mast et al., 1993 for a complete review). Skinner (1991) suggests that when the geographic distribution and ecology of related varieties is poorly known, as in the case of the cotton-top tamarin and the Panamanian tamarin, taxonomists must resort to other methods, such as morphological comparisons. Skinner (1991) compared the morphological traits for 17 characteristics among S. geoffroyi, S. leucopus, and S. oedipus. She found that S. leucopus and S. oedipus were more closely related than either species were to S. geoffroyi. Therefore, she concluded that S. oedipus and S. geoffroyi were two separate species. It is also important to note that only S. oedipus spontaneously develops colon cancer.

 Physical Description

The large shock of white fur on its head gives the cotton-top tamarin its most appropriate name. Males and females are not sexually dimorphic weighing approximately 404-417 g in the wild to 565-700 g in captivity (Savage, 1990; Savage et al., 1993). Knee-to-heel length (M=7.26 cm) and head to tail length (M=23.07 cm) appear to be similar for both wild and captive cotton-top taimarins (see Savage, 1990 for a complete review). The face of the cotton-top tamarin is black, temples and sides of head are covered with short adpressed silvery hairs. The face is adorned with grayish or whitish supraorbital band, with a grayish fringe across the muzzle to each comer of the mouth. There is a wedge-shaped midfrontal white crest. The dorsal surface of the body is primarily black or brown, while the underparts of the body, arms, and legs are predominantly white (Hershkovitz, 1977).

Scent Gland Morphology

Female cotton-top tamarins have highly developed anogenital and suprapubic scent glands. Females have larger scent glands than males. Perkins (1969) reported that the sebaceous glands, apocrine secretary coils, and the secretary ducts associated with these units were more extensive and more highly developed in females. The thickness of glandular skin also differs between the sexes, with sebaceous glands observed up to approximately 1.6 mm below the skin surface in females but only to a depth of 0.4 mm below skin surface in males. Total area of the scent glands in female cotton-top tamarins range from 7.89-8.31 CM2 (Savage et al., 1988). Use of the anogenital and suprapubic glands differ between males and females.

Distribution

Cotton-top tamarins are found only in Colombia, from the eastern bank of the Atrato River to the western bank of the Cauca and lower Magdalena Rivers, bounded by the Colombian Caribbean coast to the north. To the south, the distributional range proposed by Mast et al., (1993) follows the 1500-m contour from east to west beginning at the Cauca River and crossing the Serranfa de Ayapel and the Serranfa de San Jer6nimo (Hernandez-Camacho and Defler, 1983; 1985; Hershkovitz, 1977) (Figure 1).

Threats to the Survival of Wild Cotton-top Tamarins

Colombia is one of the most biologically diverse countries and is second only to Brazil in overall numbers of plants and animal species. Given its size (one seventh that of Brazil), Colombia harbors greater concentrations of species per unit area than any other country on the planet (Alderman, 1989; Mast et al., 1993; Mittermeier & Mast, 1990). One of the biggest threats to the cotton-top tamarin, and to Colombian biodiversity in general, is forest destruction. Colombia is among the top ten countries worldwide in terms of deforestation, and is surpassed only by Brazil, in the Western Hemisphere, in terms of numbers of hectares deforested. Each year more than 4000 km' of tropical habitat is destroyed (Myers, 1989).

Threats to wild cotton-top tamarins and many of the primates in Colombia, can be characterized as direct pressures to the animals themselves (e.g. hunting and

live capture) or dangers associated with the loss of habitat (Mast et al., 1993; Mittermeier et al., 1989). In the northern part of the cotton-top tamarin's range, the majority of the forest that has been destroyed has been for large-scale clearance for agriculture or ranching purposes. The remaining forest patches in this part of the country generally lie atop agriculturally useless land (e.g. limestone outcropping, seasonally flooded river margins) (Mast et al., 1993).

The portion of the cotton-top tamarin's habitat that lie in the foothills of the northern termini of the western and central Andean cordilleras face fuelwood collection and small-scale agricultural encroachment threats of unknown intensity. However, the most damaging imminent threat comes from flooding of forest for hydroelectric projects (see Mast et al., 1993 for a complete review).

Colombia's electric power is approximately 70% hydroelectric, yet only about 6% of the country's hydroelectric potential has been exploited to date. Planned hydroelectric projects for Colombia, if completed, would flood thousands of hectares of the country's high diversity ecosystems. One proposed hydroelectric project alone, URRA (comprised of LTRRA I and URRA 11) could flood over 60,000 ha in the upper Sin-6 river basin. This area included more than 54,000 ha of primary and secondary forest lying inside the Parramillo National Park and its buffer zone, one of the last major strongholds for the cotton-top tamarin (Mast & Cubberly, 1987; Mast & Patiiio, 1988; Mast et al., 1993; Ramirez Cerquera, 1985).

Fortunately, Colombia's power sector has avoided any major negative environmental and social impacts resulting from hydroelectric compared to other countries. In recent years under the terms of the World Bank's power sector adjustment loan (loan 2889-CO) the Colombian central power agency (ISA) and its eight regional affiliates have undertaken a program to minimize the environmental impact of hydroelectric expansion under the National Power Expansion Plan (Mast et al., 1993). Efforts have been made to develop methodologies for more effectively prioritizing projects to minimize their adverse environmental and socioeconomic impacts, to provide environmental training for power sector staff, and to develop more stringent environmental standards for hydroelectric and thermal projects (Mast et al., 1993). Mast et al., (1993) provides a detailed description of the proposed hydroelectric projects and their probably impact on the natural resources of Colombia.

In addition, to the dramatic impact forest destruction has on the future survival of this species, capture for the pet trade and/or exportation has and will continue to have, an impact on the survival of cotton-top tamarins. Between 1968 and 1972 as many as 14,000 cotton-tops were imported to the U.S. and between 30,000-40,000 were exported from Barranquilla, Colombia between 1960-1975 along (Heernandez Camacho & Cooper, 1976). The actual numbers of cotton-top tamarins captured from the wild during this period is likely to be much higher given the high number of animals that died during capture and/or export.  Despite the 1973 Colombian ban and the listing of Saguinus oedipus in Appendix I of CITES, importation of cotton-top tarnarins to the U.S. continued in small numbers, most shipped through countries such as, Panama (Mack & Mittermeier, 1984; Mittermeier & Coirnbra-Filho, 1983; Thorington, 1972). There is still an active local market for cotton-top tainarins within Colombia (Mast & Cubberly, 1987; Mast & Patifio, 1988). Wildlife dealers in Colombia are constantly selling cotton-top tamarins as pets and may be smuggled to other countries (Barbosa et al., 1988). As Mast et al., 1993 states "Notwithstanding laws to the contrary, if there is money to made through the capture and sale of wild species, there will be someone willing to take the risk to earn that money. The best way to curtail the threat posed by live captive is to eliminate all demand for wild-captured animals." (p. 37)