ISSN:0015-5713    

DOI:10.1159/000157240

出版商:S. Karger AG    

年代:1997

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000157241

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Muriquis (Brachyteles arachnoides) are unusual among polygamous primates in the nonaggressive, egalitarian relationships that exist among group members. Yet, despite their relative freedom to express strong preferences in their choice of mates, 18 sexually active females and 10 sexually active males routinely copulated with multiple partners during a 60-month period from July 1990 to June 1995 at the Estação Biologica de Caratinga on Fazenda Montes Claros, Minas Gerais, Brazil. Females with different reproductive and social histories differed in the ways they expressed their promiscuity. The number of different partners was positively related to copulation frequencies for long-term female residents, but not for recent female immigrants or mature or young males. Mother-son matings and matings between recent female immigrants and males from their natal group were rare. Preferential mating occurred between recent female immigrants and young males, while experienced long-term female residents tended to copulate more frequently with mature males. Prior reproductive experience appears to be a less important determinant of muriqui mating patterns than the constraints imposed by avoiding close inbreeding and the preferences exhibited by close social associate

ISSN:0015-5713    

DOI:10.1159/000157242

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Primates are important indicators for tropical forests as a fundamental component in the establishment of strategies for biodiversity conservation in biomes, regions and countries. Priority setting at the species’ level is dependent on taxonomic studies and the evaluation of population status. The most recent listing of the Neotropical primates recognised the existence of 16 genera, 98 species and 202 species and subspecies. Sixteen of these primates are critically endangered, 19 are endangered, and a further 35 are vulnerable according to the Mace-Lande system recently adopted by the World Conservation Union (IUCN). Thirty-five percent of the Neotropical primate taxa are threatened. In this paper we review the conservation status of these threatened primates, and analyse their distributions in 21 countries and seven phytogeographic regions, evaluating richness, endemism and number of threatened tax

ISSN:0015-5713    

DOI:10.1159/000157243

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

The geographic distribution and conservation status of the golden-headed lion tamarin, Leontopithecus chrysomelas, were studied during a survey carried out through an area of about 37,000 km2 in southern Bahia from March 1991 to March 1993. The survey involved interviews of local people and direct censusing in 33 forest patches using playback recordings of a male and female lion tamarin long-call. Populations were found to occur in 94 localities. An Appendix provides a full gazetteer of these localities and a further 28 localities recorded in previous studies. The distributional limits were found to agree closely with the ranges described by previous authors, except for its absence in the extreme north-east of its range, from the south of the Rio de Contas to the Rio Almada, where it might have become extinct. The total geographic range was estimated to cover approximately 19,462 km2, including two distinct regions in terms of land use and forest cover. The forests in both regions are severely reduced and fragmented. Unlike the other three species of lion tamarins, L. chrysomelas evidently still occurs throughout a large part of its historic range, but the fragmentation and rapid rate of forest destruction clearly indicate that the species is endangered. The Una Biological Reserve is the only protected area within its range, and is believed to be too small (7,059 ha) to maintain a genetically viable population. The conservation status of L. chrysomelas is discussed, particularly in terms of the socioeconomy of the region where it occurs, as well as the need for further ecological research.

ISSN:0015-5713    

DOI:10.1159/000157244

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Central American squirrel monkeys, Saimiri oerstedi, have never been abundant. This species is apparently extinct in Panama and nearly so in Costa Rica. Less than 4,000 are estimated to survive in Costa Rica. In recent years only a limited number of squirrel monkey troops have been documented outside of two Costa Rican national parks, Parques Nacionales Corcovado and Manuel Antonio. Numerous factors contribute to a pessimistic prognosis for this species, most importantly, the continued deforestation and tourist development with concomitant demands on prime squirrel monkey habitat from hotels, restaurants, roads, and vacation villas in the Pacific Wet Lowland habitat of squirrel monkeys. We also highlight features of the natural history of this species most relevant to conservation efforts with the goal of enhancing the success of surveys and maintenance and breeding of captive groups.

ISSN:0015-5713    

DOI:10.1159/000157245

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

A free-ranging group of Saimiri sciureus was studied in a semi-natural forest habitat in eastern Amazonia, where behaviour patterns were broadly similar to those recorded for the species in the wild. According to focal-animal samples, the monkeys spent the vast majority of their time foraging and feeding, in particular for arthropod prey, which contributed almost half of identified food items. The predation of a small-bodied bat was also observed, although the study animals did not appear to forage systematically for chiropterans in the manner recorded for Saimirí oerstedi.

ISSN:0015-5713    

DOI:10.1159/000157246

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

This large-scale geographic comparison examines the effects of subsistence hunting pressure and several indirect indicators of habitat quality on the abundance of howler monkeys {Alouatta spp.), the best studied and the most folivorous of all platyrrhine primates. Alouatta population densities were obtained from a standardized series of line-transect censuses undertaken at 23 Amazonian forest sites (1987–1995), including annually flooded (várzea), unflooded (terra firme), and eastern Amazonian transitional terra firme forests. A total of 83 density estimates from elsewhere were compiled from a comprehensive review of field studies from southern Mexico to northern Argentina. Howler density and biomass in Neotropical forests is profoundly affected by degree of hunting pressure, structural heterogeneity of the forest canopy, and to a lesser extent, the rainfall seasonality, total rainfall, and latitude of a given site. Mild gradients of forest elevation were a poor predictor of howler densities. In evergreen forests of lowland Amazonia, distance to major white-water rivers, which covaries with forest heterogeneity and soil fertility, is the best single predictor of howler densities. In Amazonia, habitat-specific patterns of distribution and abundance of Alouatta and other arboreal folivores conform to geochemical gradients determined by watershed types and their consequences for soil fertility. Results presented here confirm suggestions for Old World generalist herbivores that howler monkeys face strong dietary constraints which are most likely related to quality, phenology and productivity of digestible foliage during periods of resource scarci

ISSN:0015-5713    

DOI:10.1159/000157247

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

With the sakis (Pithecia) and the bearded sakis (Chiropotes), the uakaris (Cacajao) constitute the cebid subfamily, Pitheciinae. The most recent revision recognized six Cacajao subspecies in two species, confined to the Amazon basin. Before 1970 most field information derived from 19th century travellers. Studies still lag behind those of other cebid genera. This paper summarises the known ecology of Cacajao, and identifies future research and conservation priorities. The relevance of Pleistocene refugia and metachromism in analysing its biogeography is discussed. Range size remains obscure but, with the exception of C. c. calvus, may be extensive, as all other subspecies appear to migrate in the dry season from flooded riverine forest to terra firme. Observed group size ranges from 5 to 50, indicating the operation of a fission-fusion society. Social organization appears to be multi-male and non-hierarchical. This accords with the minimal sexual dimorphism. The highly developed canines function primarily as fruit openers. Cacajao is a dietary specialist on hard-shelled fruit, and appears unique among Amazonian cebids in its dependence (at least seasonally) on riverine forests. Hunting may be a problem locally, but local taboos sometimes offer protection. They appear vulnerable to habitat disturbance. On the Rio Negro, the range of C. m. melanocephalus appears to have greatly diminished. To ensure protection of viable populations, the inferred dietary dependence on seasonal migration may require accommodation. Research priorities include the status, habitat preference, diet and social ecology of all taxa except C. c. calvus. A more complete knowledge of the biogeography of the genus would be valuable.

ISSN:0015-5713    

DOI:10.1159/000157249

出版商:S. Karger AG    

年代:1997

数据来源: Karger

摘要:

Despite a large body of data on diet and ranging patterns in prosimians, monkeys and apes, little is known regarding the types of information that non-human primates use when making foraging decisions. In a series of controlled field experiments, we tested the ability of wild capuchins (Cebus capucinus) at La Suerte Biological Research Station in north-eastern Costa Rica to remember the spatial positions of 13 feeding platforms and use olfactory and visual cues to identify baited (real bananas) versus sham (plastic bananas) feeding sites. The results indicate that when ‘place’ was predictable, the capuchins learned the spatial locations of food and non-food sites rapidly (one-trial learning). In a second experiment, the positions of baited feeding sites were random. In the absence of other information, the capuchins used the presence of a local landmark cue (yellow block) placed at reward platforms to select feeding sites. In a final experiment, there was evidence that expectations regarding the amount of food available at a platform (2 bananas vs. 1/2banana) had a significant influence on capuchin foraging decisions. Although the capuchins were sensitive to changes in experimental conditions, when they were given conflicting cues, spatial information was predominant over other information in selecting feeding si

ISSN:0015-5713    

DOI:10.1159/000157250

出版商:S. Karger AG    

年代:1997

数据来源: Karger