98 



NORTH AMERICAN FAUNA 75 



ORDER PRIMATES 



Primates currently are protected throughout Costa Rica, and probably little 

 poaching occurs. However, historically in this region, spider, howler, and capuchin 

 monkeys were a meat source. Use of these primates for food continued in some 

 areas of Costa Rica as late as the early 1970's, and undoubtedly the indigenous 

 Indians in remote areas are still harvesting them. As the monkeys at La Selva in 

 recent years have received complete protection from hunters, they are undoubted- 

 ly less wary of humans. Perhaps their recent abundance is attributable to a decrease 

 in wariness and thus increased visibility as well as an increase in absolute numbers. 



Primate populations throughout much of the Caribbean lowlands of Central 

 America were decimated by an epidemic of mosquito-borne yellow fever during 

 the early 1950's (see Fishkind and Sussman 1987, and references therein). Although 

 data are not available for La Selva or the adjacent Braulio Carrillo region, we assume 

 that this epidemic had a tremendous negative effect on the populations of indigenous 

 primates. Far fewer primates were observed at La Selva during the late 1960's, 

 1970' s, and early 1980's than in similar tracts of primary forest elsewhere in the 

 Neotropics. During the past several years, however, primate populations at La Selva 

 have certainly rebounded. It is now common to see capuchin, howler, and spider 

 monkeys almost daily and often in large troops. 



Family Cebidae 



Alouatta palliata 

 Mantled Howler Monkey, Mono Congo or Mono AuUador 



Mantled howler monkeys are found from southern Mexico south through Cen- 

 tral America to extreme northwestern South America, where they occur on the 

 western slope of the Andes in Colombia and Ecuador to Guayaquil (Fig. 77). Two 

 subspecies are found from sea level to forested high elevations (2,500 m) in Costa 

 Rica. The nominate race, Alouatta palliata palliata, is widespread in Costa Rica, 

 including Parque Nacional Braulio Carrillo; A. p. aequatorialis is restricted to ex- 

 treme southwestern Costa Rica on the Osa Peninsula. This species adapts well to 

 the presence of humans, usually being as abundant near rural towns and in second 

 growth forests as it is in primary forests. 



Howler monkeys were seen or heard by us on numerous occasions in the park 

 from the lower elevations to 1 ,200 m. Although they are widespread in Costa Rica, 

 howler monkeys are less abundant within Parque Nacional Braulio Carrillo than 

 we have observed them to be in other areas of the country. Additionally, both howler 

 monkeys and white-faced capuchins were wary of us, suggesting that they have 

 been hunted in this area. Corroborating this is Vaughan's (1972) observation of 

 howler monkeys that were shot for human consumption in the vicinity of Cariblanco. 



Howler monkeys were observed along the trail from 100 to 200 m; calling 

 troops heard at 200, 300, and 700 m; and a troop observed at 500 m. This is a 

 commonly reported species at La Selva, although it is not as abundant there as 

 are white-faced capuchins (Timm, in press). These monkeys have been seen or 

 heard howling at La Selva in every month of the year. Troop sizes are variable 



