Alouatta caraya: Population density and demography in Northern Argentina

Abstract

A long-term study was carried out on a black howler monkey (Alouatta caraya) population living in 150 ha of forest patches spread out in a 3,000 ha rural area in Northern Argentina. A total of 22 different groups were located between 1980 and 1984 and 11 of these were monitored regularly during 28 months.Ecological density varied between 12.14 and 12.93 groups per sq km of tall dense forest (0.80 to 1.15 ind.iha; biomass 306 to 365 kgisq km). Solitaries and small associations of adult or subadult individuals of both sexes were also recorded but occupied habitats of inferior quality. Mean sizes of reproductive groups varied from 6.4 to 8.4 and the range was 3 to 15 individuals. Reproductive groups had 1 to 3 adult males, 1 to 3 adult females, and several immatures. Sex ratio was biased toward females among the adults but it varied in other age classes. Births occurred throughout the year showing a peak in the colder and drier season. Subadult or young adult males and females dispersed from suspected natal groups and became solitaries or joined associations. Males invaded groups and displaced or coexisted with resident males. Infanticides and disappearances of infants were associated with male changes.Comparative censuses on an island not far from the main study area showed higher density and biomass (2.8 ind./ha; 1,117 kg/sq km) and different group sizes and composition. Habitat features as well as the history of each study site may account for the observed demographic differences.

Comparison of the diet of Alouatta caraya (Primates: Atelidae) between a riparian island and mainland on the Upper Parana River, southern Brazil

“…On the mainland, on the other hand, during spring leaves of F. obtusiuscula were consumed in greater proportions. On the island, instability imposed by variable water levels, favors those plants that grow rapidly and tolerate flooding (RUMIZ 1990, CAMPOS & SOUZA 1997, such as C. pachystachya, which is dominant in riparian forests . The abundance of the most consumed species by the animals may reflect environmental quality (GAULIN et al 1980) and perhaps favors howlers in this area.…”

Diet and Activity Patterns of Black Howler Monkeys Alouatta Caraya (Humboldt, 1812, Primates, Atelidae) in Ecotone Cerrado-Pantanal in the Left Bank of Aquidauana River, Mato Grosso Do Sul, Brazil

“…The social organization and behavior of the genus Alouatta can be characterized mainly by polygyny, low activity rates and high levels of folivory in most populations (Bicca-Marques 2003, Miranda & Passos 2004, Ludwig et al 2008. Alouatta caraya follows this general pattern, although there are only some ecological data available for the species, most of which were obtained from studies in the extreme south of the species geographical distribution (Rumiz et al 1986, Rumiz 1990, Bicca-Marques 1991, Agoramoorthy & Lohmann 1999, Bravo & Sallenave 2003. Until the present study, only two (Nantes & Rímoli 2008, Odalia-Rímoli et al 2008 were available and provided ecological data of the contact zone of the Cerrado and Pantanal biomes, the region known as Bororo (Coimbra-Filho 1982), and one in the Atlantic Forest/Cerrado contact zone (Ludwig 2006).…”

Consumo de néctar por <i>Aotus lemurinus</i> y su rol como posible polinizador de las flores de <i>Inga edulis</i> (Fabales: Mimosoideae)

“…The study was carried out at San Cayetano (27° 30' S, 58° 41' W), Corrientes Province, Argentina (Rumiz, 1990). The climate is subtropical with an average annual temperature of 21.7° C and an average annual of rainfall of 1,230 mm; the rainfall decreases slightly in the winter (July to August) (Zunino et al, 2007).…”