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CONTENTS Introduction 1 Richard W. Thorington, Jr., and Paul G. Heltne Censusing Alouatta palliata, Ateles geoffroyi, and Cebus capucinus in the Costa Rican Dry Forest 4 Curtis Freese Comparison of Census Data on Alouatta palliata from Costa Rica and Panama 10 Paul G. Heltne, Dennis C. Turner, and Norman J. Scott, Jr. Primate Populations in Chiriqui, Panama 20 John D. Baldwin and Janice I. Baldwin Movements of a Wild Night Monkey (Aotus trivirgatus) 32 Richard W. Thorington, Jr., Nancy A. Muckenhirn, and Gene G. Montgomery The Nonhuman Primates of Colombia 35 Jorge Hernandez-Camacho and Robert W. Cooper Neotropical Primates: Aspects of Habitat Usage, Population Density, and Regional Distribution in La Macarena, Colombia 70 Lewis L. Klein and Dorothy J. Klein Notes on the Ecology and Behavior of the Pygmy Marmoset (Cebuella pygmaea) in Amazonian Colombia 79 Martin Moynihan The Nonhuman Primate Trade in Colombia 85 Ken M. Green Addendum to the Nonhuman Primate Trade in Colombia 99 Nancy A. Muckenhirn The Population and Conservation of Howler Monkeys in Venezuela and Trinidad 101 Melvin Neville Problems and Potentials for Primate Biology and Conservation in the New World 110 Paul G. Heltne and Richard W. Thorington, Jr. Subject Index 125 Author Index 131 Participants 133 Contributors 135
INTRODUCTION Richard W. Thorington, Jr., and Paul G. Heltne New World monkeys have constituted about one- quarter of all primates utilized for biomedical purposes in recent years in the United States. Next to the rhesus monkey (Macaca mulatta), the South American squir- rel monkey (Saimiri sciureus) has been the most frequently used experimental primate. Several of the New World species are critical for certain types of research, e.g., the night monkey (Aotus) for studies of malaria (Millar, 1974) and some of the tamarins of the genus Saguinus for studies of viral sarcoma and hepatitis (Deinhardt, 1971). The ceboid monkeys offer special opportunities for the study of the ecology of coexistent primate species in highly diverse com- munities. Some species, like the marmosets, provide excellent subjects for investigation of parental be- havior. Recent work has pointed to the extreme similarities between the morphology of some extant New World monkeys and Proconsul africanus of the African Miocene (Schon and Ziemer, 1973). Other anatomical studies have emphasized similarities of hip morphology in certain ceboids and man (Stern, 1971). So little is known of most New World genera that further research will almost certainly pay unexpected dividends for medicine and biology. Not widely appreciated is the fact that these impor- tant species are under severe pressure due to the widespread destruction of their forest habitats. In an effort to emphasize the present status of primate populations, the organizers of this symposium invited participants who had done recent fieldwork in Central and South America. They were requested to sum- marize available population data and ecological infor- mation relevant to the present and future conditions of wild neotropical primates. There were obvious gaps in coverage, for example, a lack of papers on Brazilian primates. To our knowledge, there are simply no data available on the status of Brazilian populations of primates in the Amazon. Certain taxonomic underrep- resentations were also evident, such as the absence of material dealing with any of the species of the Pithecinae, whereas studies of Alouatta are overrep- resented. We believe these omissions and overrep- resentations, both geographically and taxonomically, were a valid reflection of the information, and lack of information, on South American monkeys at the time of the symposium. The situation has changed only slightly since then. We hope that publication of this volume and the recognition of hiatuses will stimulate future work that will narrow these gaps. The distribution of primates is usually documented from museum collections. This has the advantage that the identifications can be reevaluated and verified. There are several disadvantages. Most collections are old and specimens may have been obtained from areas in which the species no' longer occurs due to habitat changes or other factors. Also, museum collections never document the ranges of animals as thoroughly as the local naturalist can. Nevertheless, good descrip- tions of the geographic ranges of South American primates are available in the literature (e.g., Law- rence, 1933; Kellogg and Goldman, 1944; Hershkovitz, 1949, 1963, 1968: Cabrera, 1957; Fooden, 1963). Un- fortunately, the most readily available syntheses (Hill., 1957, 1960, 1962) of geographic ranges, complete with
8 FREESE the park's population was between 250 and 350 indi- viduals. Most troops contained between 15 and 20 individu- als. Infrequently, small groups of only one to six individuals were encountered, sometimes under cir- cumstances indicating that particular groups were temporarily separated from larger troops. Adult females outnumbered adult males. One troop inhabit- ing a semideciduous forest contained about five adult males (one was subadult), six or seven adult females (at least two were subadults), three or four juveniles, and two infants. If individuals classified as subadults were included instead in the juvenile category, the age distribution for this troop would more closely approx- imate Oppenheimer's (1968) results. The largest troop size observed by Oppenheimer (1968) on Barro Colorado Island was 15, although he noted that significantly larger troops have been seen by other observers. He also found there were more females than males and usually twice as many infants and juveniles as adults. The territory of one Santa Rosa troop was estimated at approximately 0.5 km2, as compared to an average of about 0.9 km2 for slightly smaller troops observed by Oppenheimer. Op- penheimer's data suggest that more Cebus births occur during the dry season or early wet season on Barro Colorado Island. I observed infants during every month and noted one birth at the beginning of the dry season and another at the beginning of the wet season. However, these data are too inconclusive to determine the presence or absence of a seasonal reproductive peak for Cebus in Santa Rosa. SUMMARY Of the three monkey species in Santa Rosa National Park in the dry forest of Guanacaste Province, Costa Rica, Cebus were the most numerous, Ateles inter- mediate in number, and Alouatta the least numerous. Similarly, Cebus had the most extensive distribution and Alouatta the smallest. John Christy (personal communication) has found in another area of the Costa Rican dry forest that Alouatta are more numerous than Cebus and that Ateles are absent. It seems likely that Alouatta inhabit almost exclu- sively evergreen forests in the park because they are largely folivores. During the dry season leaves are scarce in the deciduous forests, and the howlers are not mobile enough to regularly penetrate deciduous forests to reach fruiting trees. Ateles probably have a larger proportion of fruits to leaves in their diet than Alouatta, and they are much more mobile. Because dry-season fruiting is common in the deciduous forest, Ateles can obtain the most important part of their diet in the deciduous forest, as well as in the evergreen forests, year-round. And they can easily cover long distances to obtain fruit in deciduous forests and leaves in evergreen forests. Also, the small groups of Ateles can probably more efficiently utilize the widely scattered fruit sources than the large Alouatta troops, because more time can be spent at each source before it is exhausted. Similarly, the differences in the diet and locomotor abilities of Cebus compared to the other two species suggest why they are more widespread in Santa Rosa. Cebus eat primarily fruits and insects, both of which occur year-round in varying abundance in the deciduous forests. Insects, but possibly not fruits, also can be found year-round in young, second- ary, deciduous growth; and insect-foraging by Cebus appears to be a frequent activity in such growth. Cebus are usually widespread during insect-foraging so that each individual is a distinct foraging unit covering a different area. Important for exploiting young, second- ary growth are the comparatively small size of Cebus and their quadrupedal locomotion, which allow easier movement through the weakly structured, dense, short vegetation. The physiognomy and types of food resources of young, deciduous forests may largely exclude their utilization by Ateles and Alouatta. The extremely variable forests of Santa Rosa con- trast with the relatively uniform, tall, evergreen forest on Barro Colorado Island. Within a small area, appar- ent differences in suitable forest habitat exist for each species. Models of the division of resource space can be tested. The marked seasonality and relative lack of uniformity of the tropical dry forest, as compared to the tropical wet forest, have certainly imposed differ- ent pressures upon resident primates. These pres- sures may be reflected in behavioral, physiological, and other biological differences between tropical wet and tropical dry forest monkey populations. Compara- tive studies of troops of the same species in different habitats within the park and between wet and dry seasons could greatly enhance our understanding of socioecology in New World primates. Rummer (1971) has discussed the importance of understanding ecolog- ical adaptation and resource partitioning among pri- mates. Beyond the boundaries of the park, the rapid cutting and clearing of the tropical dry forest in northwestern Costa Rica continues. Ateles are already scarce in this region, and Alouatta and Cebus populations will be seriously affected if present trends continue. If size- able populations of the primate species and other fauna are to persist, land-use practices must change. Hope- fully, the continued protection of wildlife and forests in Santa Rosa by the Costa Rican government will insure
CENSUSING ALOUATTA PALLIATA, ATELES GEOFFROYI, AND CEBUS CAPUCINUS 9 their survival under more or less natural conditions in this biologically unique area. ACKNOWLEDGMENTS Special thanks are due to the other three biologists in the parkâ Douglas Boucher. Steve Cornelius, and Keither Leberâwhose observations and helpful suggestions have added immensely to the content of this chapter. I also want to thank the director of the Costa Rica National Parks Department, Mario Boza, for his cooperation, and the administrator of Santa Rosa, Alvaro Ugalde, for his cooper- ation and valuable observations. I extend my appreciation to Dr. Paul Heltne, who offered helpful suggestions on the manuscript. Finally, my gratitude goes to the park guards, who often pointed the way to a monkey troop. REFERENCES Carpenter, C. R. 1934. A field study of the behavior and social relations of howling monkeys (Alouatta palliata). Comp. Psychol. Monogr., 10:1-68. Carpenter, C. R. 1935. Behavior of red spider monkeys in Panama. J. Mammal. 16(3): 171-180. Chivers, D. J. 1969. On the daily behavior and spacing of howling monkey groups. Folia Primatol., 10:48-102. Collias, N. E., and C. H. Southwick. 1952. Afield study of population density and social organization in howling monkeys. Proc. Am. Philos. Soc., 96:143-146. Eisenberg, J. F., and R. E. Kuehn. 1966. The behavior of Ateles geoffroyi and related species. Smithson. Misc. Collect., 151(8): 1-63. Glander, K. 1971. The howlers of Finca La Pacifica. M.S. Thesis. Univ. of Chicago. 90 pp. Kummer, H. 1971. Primate Societies. Aldine and Atherton, Chicago and New York. 160 pp. Moynihan, M. 1970. Some behavior patterns of platyrrine monkeys. II. Saguinus geoffroyi: and some other tamarins. Smithson. Contrib. Zool., no. 28. Oppenheimer, J. R. 1968. Behavior and ecology of the white-faced monkey, Cebus capucinus. Ph.D. Thesis. Univ. of Illinois. 181 pp. Richard, A. 1970. A comparative study of the activity patterns and behavior of Alouatta villosa and Ateles geoffroyi, Folia Primatol.. 12:241-263.