Fecal samples were collected from black howler monkeys (Alouatta pigra) in north central Belize and analyzed for evidence of endoparasite life stages. At least six types of endoparasites were found in Alouatta pigra fecal samples collected in the Lamanai Archaeological Reserve and the Community Baboon Sanctuary in 1999. These include a digenean trematode, an oxyurid nematode, a strongyle-type nematode, an ascarid presumed to be Ascaris sp., Entamoeba coli and Iodamoeba bütschlii. Higher trematode prevalence was found in adult Alouatta pigra compared to juveniles and higher prevalence of nematode larvae in all animals was found in the wet season compared to the dry season.

A literature review of howler parasites provides the basis for an overview of the ecological significance of parasite surveys in primates. Within this framework, we have added insights into the interactions between primate hosts and their parasites from a long-term study in Costa Rica. We collected fecal samples from mantled howlers (Alouatta palliata) over a 9-year period (1986–1994 inclusive) and analyzed them for parasite eggs, larvae, cysts, and oocysts. We found many misperceptions inherent in the typical methodology of primate parasite surveys and in the reporting of the findings. Our work in Costa Rica suggests that a snapshot effect occurs with most surveys. A static view does not reflect the dynamic and changing ecological interaction between host and parasite. We describe some problems with parasite data analyses that emphasize the need for long-term longitudinal surveys in wild primate groups.

Examinations of primate parasitic infections can inform both primatologists and parasitologists about evolutionary and ecological relationships. Interspecific, intraspecific, and interindividual variation in parasitic infections may correlate with environmental, demographic, behavioral, and human variables. Understanding these relationships is particularly important for conservation management issues for endangered species. We describe techniques for the noninvasive collection and preservation of fecal samples from wild primates and the salvaging of parasitological information from primate hosts in the field.

One hundred twenty-eight fecal exami- nations from 57 muriquis or woolly spider monkeys, Brachyteles arachnoides, and 62 fecal samples from 9 brown howling monkeys, Alouatta fusca, that coexist in the Atlantic forest in southeastern Brazil were ex- amined for evidence of parasite infections. Hosts from 4 sites, 2 in Minas Gerais (EBC and FE) and 2 in Sao Paulo (FBR and PECB), showed differences in parasite prevalence and diversity. Neither muriquis nor brown howling monkeys from site 1 (EBC) revealed parasites. Monkeys from site 2 (FE) had only eggs presumed to be Strongyloides cebus and those from site 3 (FBR) had only Trypanoxyuris brachytelesi. Eggs and larvae pre- sumed to be Strongyloides cebus, Trypanoxyuris brach- ytelesi, Graphidiodes berlai, and an unidentified dige- nean were found at site 4 (PECB). The 4 study sites differ substantially in size (40-37,000 ha), degree of human disturbance, climate, plant species composi- tion, and muriqui densities. Contrary to expectations, muriquis from the largest and least-disturbed forest (with the lowest population density) had the highest prevalence and diversity of parasitic infection. A va- riety of factors, including vegetation and climatic dif- ferences, could explain this paradoxical pattern. How- ever, the fact that PECB is the site least affected by human disturbance also suggests that the complex eco- logical web involved in parasitic transmission has been disrupted at the other sites. Our findings reaffirm the importance of using parasites as ecological indicator species in studies of wild primates and suggest that management plans which involve translocations must be sensitive to the potential effects of parasites on naive hosts.

One hundred twenty-eight fecal exami- et a1. (1969) reported both .8. arachnoides and