Cebus Apella Nigritus Research Articles

Food-associated Calls of Tufted Capuchin Monkeys (Cebus Apella Nigritus) Are Functionally Referential Signals

In this paper I explore the possibility that tufted capuchin monkeys ( Cebus apella nigritus ) have food-associated calls, vocalizations that are functionally referential and may provide information about the presence of food to other individuals in the group. Functionally referential signals are those that meet two criteria: (1) they are context specific and (2) they elicit a response that is context independent. The study was conducted on a wild group of capuchins in a subtropical rain-forest in NE Argentina. To evaluate the degree of context specificity of the vocalizations I obtained focal animal sound recordings of the vocalizations emitted by individually recognized animals and indicated the socio-ecological context of call emission. I performed playback experiments to see if animals can respond to the food-associated calls in the absence of contextual information. Two vocalizations, grgrs and whistle series, were considered putative food-associated calls, because previous observations suggested an association of these vocalizations with the presence of food. Grgrs and whistle series were given at a higher rate when the focal animal was feeding on fruit at a highly productive source than in other socioecological contexts. Whistle series were also produced, although at a lower rate, in contexts other than feeding but whistle series given when feeding belong to an acoustically distinct type. Animals responded to the playback of food-associated calls with a rapid and direct movement to the speaker in almost 50% of the trials. Capuchins did not show this response to the playback of control stimuli. Food-associated calls in tufted capuchins can thus be considered functionally referential signals.

Reproductive Socioecology of Tufted Capuchins (Cebus apella nigritus) in Northeastern Argentina

We describe the reproductive parameters of tufted capuchins (Cebus apella nigritus) in the Iguazu National Park, NE Argentina. We obtained data on six different groups (33 individually recognized adult females) studied for periods of 2–9 years. Estimated birthrate is 0.59 infants per female per year in unprovisioned groups. A group that was provisioned for 6 years during the winter period of low fruit availability (May–August), showed a similar birth rate of 0.61, but a lower infant mortality rate than unprovisioned groups. The birthrate estimated for this population is higher than the one reported for white-faced and wedge-capped capuchins. The mean interbirth interval is 19.35 months, but a female can have infants in successive years, even when her previous infant has survived. The modal age at first delivery is 7 years, which is similar to the one observed in wedge-capped capuchins. When young adult females come into estrous they avoid copulating with the alpha male that sired them, thus providing evidence for a behavioral mechanism of inbreeding avoidance. Births are very seasonal at Iguazu, occurring during the spring and summer months (October–February) when food availability is at its peak. Tufted capuchins at Iguazu are more seasonal breeders than other capuchin populations, probably as a result of their more seasonal environment. The secondary sex ratio does not deviate significantly from 1:1, despite the known ability of capuchins to adjust secondary sex ratio to local conditions.

Population density of primates in a large fragment of the Brazilian Atlantic rainforest

We performed a line transect survey (352.4 km) of primates in the Serra de Paranapiacaba, at one of the largest relatively undisturbed fragments of the Atlantic rainforest of Southeastern Brazil (ca. 1400 km2), in August 1998. The brown capuchin, Cebus apella nigritus, was the most common species found in the area (20 groups, density estimate: 5.31 ± 2.05 individuals per km2, mean ± SE). Nine groups of the brown howler monkey, Alouatta guariba clamitans, and eight of the woolly spider monkey, Brachyteles arachnoides arachnoides, were also recorded, with preliminary density estimates of 0.79 ± 0.40 and 2.33 ± 1.37 individuals per km2, respectively. Density estimates for these species in other fragments of Atlantic rainforest are reviewed, showing that densities in Paranapiacaba are among the lowest reported. It is suggested that the higher densities reported for isolated populations in small forest patches (<50 km2) is related to the absence of main primate predators, the density compensation phenomenon and the ecological plasticity of some primate species. In contrast, local extinction in many small patches is probably related to hunting pressure. Given the important primate populations found in the Paranapiacaba fragment, conservation strategies for the studied species should give priority to effective protection of the largest remnant fragments from illegal hunting and deforestation, rather than translocation of individuals or captive breeding programs to introduce monkeys in small forest fragments vulnerable to hunting and of uncertain future.

Home‐range use by the tufted capuchin monkey (Cebus apella nigritus) in a subtropical rainforest of Argentina

AbstractThe pattern of home‐range use by seven groups of tufted capuchin monkeys Cebus apella nigritus is described in the Iguazú National Park, Argentina, during 1991–94. The seasonal changes in home‐range use by one of these groups between August 1997 and December 1998, are correlated with changes in food distribution and availability. Fruit availability was estimated with fruit traps, and the abundance and distribution of food was experimentally changed within the home range of one group by using feeding platforms filled with bananas. Average home‐range size is 161 ± 77 ha (range = 81–293 ha, n= 7). There is a positive relationship between the number of females per group and home‐range size. Neighbouring groups have partially overlapping home ranges and aggressive relationships. Fruit abundance is scarce during the winter and peaks during the spring and early summer. The pattern of home‐range use by the main study group of capuchins was consistent with the hypothesis that fruit distribution and availability is the most important factor affecting the spatial use of their range. This is evidenced by the changes in range size and in range use as the distribution and abundance of their main fruit sources change seasonally. Range use shifted dramatically during the experimental phase of this study; the capuchins reduced their range and most frequently visited the areas where the feeding platforms were located. For most populations of frugivorous monkeys, fruit distribution and availability are the main factors that determine the pattern of home‐range use. However, in some populations the availability of water sources and sleeping sites can have some effect on range use. For capuchin monkeys in particular, within‐species variation in home‐range size, degree of range overlap and interactions between neighbouring groups are large and do not serve to characterize any species of Cebus monkeys.

Sleeping site preferences in tufted capuchin monkeys (Cebus apella nigritus)

The characteristics and availability of the sleeping sites used by a group of 27 tufted capuchin monkeys (Cebus apella nigritus) were studied during 17 months at the Iguazú National Park, Argentina. We tested different hypotheses regarding possible ultimate causes of sleeping-site selection. Most sleeping sites were located in areas of tall, mature forest. Of the 34 sleeping sites the monkeys used during 203 nights, five were more frequently used than the others (more than 20 times each, constituting 67% of the nights). Four species of tree (Peltophorum dubium, Parapiptadenia rigida, Copaifera langsdorfii and Cordia trichotoma) were the most frequently used. They constituted 82% of all the trees used, though they represent only 12% of the trees within the monkeys' home range which had a diameter at breast height (DBH) > 48.16 cm (1 SD below the mean DBH of sleeping trees). The sleeping trees share a set of characteristics not found in other trees: they are tall emergent (mean height ± SD = 31.1± 5.2 m) with large DBH (78.5 ± 30.3 cm), they have large crown diameter (14± 5.5 m), and they have many horizontal branches and forks. Adult females usually slept with their kin and infants, while peripheral adult males sometimes slept alone in nearby trees. We reject parasite avoidance as an adaptive explanation for the pattern of sleeping site use. Our results and those from other studies suggest that predation avoidance is a predominant factor driving sleeping site preferences. The patterns of aggregation at night and the preference for trees with low probability of shedding branches suggest that social preferences and safety from falling during windy nights may also affect sleeping tree selection. The importance of other factors, such as seeking comfort and maintaining group cohesion, was not supported by our results. Other capuchin populations show different sleeping habits which can be explained by differences in forest structure and by demographic differences. Am. J. Primatol. 50:257–274, 2000. © 2000 Wiley-Liss, Inc.

Habitat, density and group size of primates in a Brazilian tropical forest.

Habitats, population densities and group sizes of 5 primate species (Callithrix flaviceps, Callicebus personatus personatus, Cebus apella nigritus, Alouatta fusca clamitans, and Brachyteles arachnoides) were estimated, using the method of repeated transect sampling, in an area of montane pluvial forest in eastern Brazil (Atlantic forest). A. fusca and C. apella had the highest densities in terms of groups and individuals per square kilometer, respectively, while B. arachnoides was least abundant. The highest primate densities were observed in areas of secondary vegetation. Both group sizes and population densities for the 5 species were generally lower at the Reserva Biologica Augusto Ruschi than those reported in other areas of Atlantic forest. Hunting pressure and the different carrying capacity of the habitat are suggested as possible causes for the low number of sightings registered for these species.

Female Primate Sexual Behavior and Conception: Are There Really Sperm to Spare? [and Comments and Reply

Female Primate Sexual Behavior and Conception: Are There Really Sperm to Spare? [and Comments and Reply