Male-male affiliation and cooperation characterize the social behavior of the large-bodied pitheciids, Chiropotes and Cacajao: A review.

Cooperation and affiliation between males may be key to the evolution of large multimale-multifemale primate groups in some species. Cacajao and Chiropotes form multimale-multifemale groups larger than those of most other platyrrhines (Cacajao: over 150 and Chiropotes: up to 80 individuals), and groups exhibit a high degree of fission-fusion dynamics. In both genera, males engage in affiliative, sex-specific behaviors and form all-male parties. Males in both genera also have conspicuous genitalia but can demonstrate sexual crypsis, or mimicry, wherein testes are retracted, resembling labia. Observed egalitarian interactions among males suggest that there is scramble competition for access to females, and aggression between males is uncommon relative to other social primates. As of yet, there are no genetic data to clarify dispersal patterns, and while relatedness among males would in part explain their affiliative relationships, there is some limited evidence for dispersal by males in Cacajao. In this review of recent studies of male-male social interactions in Chiropotes and Cacajao, we posit that the ability to maintain large groups in these genera may be related to the affiliative and perhaps coalitionary relationships between males, who may or may not be related. Affiliative male-male relationships may allow for monopolization of groups of females and facilitate group cohesion by reducing intragroup aggression; however data on male-male interactions with identified individuals will be required to determine patterns of affiliation, while genetic studies may be the most practical way of determining dispersal patterns for these genera.

Mixed-species associations in cuxiús (genus Chiropotes).

Polyspecific or mixed-species associations, where two or more species come together to forage and travel as a unit, have been reported in many primate species. These associations appear to offer a number of benefits to the species involved including increased foraging efficiency and decreased risk of predation. While several researchers have suggested that cuxiús (genus Chiropotes) form mixed-species associations, previous studies have not identified the circumstances under which cuxiús form associations or whether they form associations more often than would be expected by chance. Here we present data on the formation of mixed-species associations by four species of cuxiús at eight different sites in Brazil, Suriname, and Guyana. We analyzed data from two of the study sites, (Biological Dynamics of Forest Fragments Project (BDFFP), Brazil and the Upper Essequibo Conservation Concession (UECC), Guyana, to assess whether associations occurred more than would be expected by chance encounters and identify the factors influencing their formation. Cuxiús showed a high degree of inter-site variation in the frequency of time spent in association (ranging from 2 to 26% of observation time) and duration of associations (mean duration from 22 min to 2.5 hr). Sapajus apella was the most common association partner at most sites. At BDFFP, cuxiús formed associations more frequently but not for longer duration than expected by chance. For much of the year at UECC, associations were not more frequent or longer than chance. However, during the dry season, cuxiús formed associations with S. apella significantly more often and for longer duration than predicted by chance. Cuxiús at UECC formed associations significantly more often when in smaller subgroups and when foraging for insects, and alarm called significantly less frequently during associations. We suggest cuxiús form mixed-species associations at some sites as an adaptive strategy to decrease predation risk and/or increase foraging efficiency.

Geographic comparison of plant genera used in frugivory among the pitheciids Cacajao, Callicebus, Chiropotes, and Pithecia.

Pitheciids are known for their frugivorous diets, but there has been no broad-scale comparison of fruit genera used by these primates that range across five geographic regions in South America. We compiled 31 fruit lists from data collected from 18 species (three Cacajao, six Callicebus, five Chiropotes, and four Pithecia) at 26 study sites in six countries. Together, these lists contained 455 plant genera from 96 families. We predicted that 1) closely related Chiropotes and Cacajao would demonstrate the greatest similarity in fruit lists; 2) pitheciids living in closer geographic proximity would have greater similarities in fruit lists; and 3) fruit genus richness would be lower in lists from forest fragments than continuous forests. Fruit genus richness was greatest for the composite Chiropotes list, even though Pithecia had the greatest overall sampling effort. We also found that the Callicebus composite fruit list had lower similarity scores in comparison with the composite food lists of the other three genera (both within and between geographic areas). Chiropotes and Pithecia showed strongest similarities in fruit lists, followed by sister taxa Chiropotes and Cacajao. Overall, pitheciids in closer proximity had more similarities in their fruit list, and this pattern was evident in the fruit lists for both Callicebus and Chiropotes. There was no difference in the number of fruit genera used by pitheciids in habitat fragments and continuous forest. Our findings demonstrate that pitheciids use a variety of fruit genera, but phylogenetic and geographic patterns in fruit use are not consistent across all pitheciid genera. This study represents the most extensive examination of pitheciid fruit consumption to date, but future research is needed to investigate the extent to which the trends in fruit genus richness noted here are attributable to habitat differences among study sites, differences in feeding ecology, or a combination of both.

Strategies for navigating large areas: a GIS spatial ecology analysis of the bearded saki monkey, Chiropotes sagulatus, in Suriname.

Animals with long day paths and large home ranges expend a considerable amount of energy on travel. Studies have shown that in the interest of reducing energy expenditure, animals selectively navigate the landscape using a variety of strategies. However, these studies have generally focused on terrestrial animals. Here we present data on an exceedingly mobile arboreal animal, bearded saki monkeys, in a topographically variable landscape in Suriname. Using ArcMap and Google Earth, we explore two potential navigation strategies: the nonrandom use of travel areas and the use of ridges in slope navigation. Over a year of data collection, bearded sakis were found to use relatively long travel paths daily, use some areas more intensely than others for travel, and when travel paths were converted to strings of points, 40.3% and 63.9% of the points were located on (50 m from the main ridgeline) or near (100 m from the main ridgeline) ridge tops, respectively. Thus in a habitat of high relief we found support for intensive use of ridge tops or slopes close to ridge tops by bearded sakis. Selective habitat use may be related to surveying tree crowns for fruit by large, fast moving groups of bearded sakis or monitoring the presence of potential predators.

Natural canopy bridges effectively mitigate tropical forest fragmentation for arboreal mammals.

Linear infrastructure development and resulting habitat fragmentation are expanding in Neotropical forests, and arboreal mammals may be disproportionately impacted by these linear habitat clearings. Maintaining canopy connectivity through preservation of connecting branches (i.e. natural canopy bridges) may help mitigate that impact. Using camera traps, we evaluated crossing rates of a pipeline right-of-way in a control area with no bridges and in a test area where 13 bridges were left by the pipeline construction company. Monitoring all canopy crossing points for a year (7,102 canopy camera nights), we confirmed bridge use by 25 mammal species from 12 families. With bridge use beginning immediately after exposure and increasing over time, use rates were over two orders of magnitude higher than on the ground. We also found a positive relationship between a bridge's use rate and the number of species that used it, suggesting well-used bridges benefit multiple species. Data suggest bridge use may be related to a combination of bridge branch connectivity, multiple connections, connectivity to adjacent forest, and foliage cover. Given the high use rate and minimal cost, we recommend all linear infrastructure projects in forests with arboreal mammal populations include canopy bridges.

Records of Coendouichillus (Rodentia, Erethizontidae) from the Lower Urubamba Region of Peru.

Coendouichillus was first described in 2001 by Voss and da Silva, with a range from Amazonian Ecuador to Iquitos, Peru. Here, we describe an adult female Coendouichillus specimen collected in a Tomahawk trap in the forest canopy of the Lower Urubamba Region of Peru in October 2013. We also describe pathologies and behaviors observed through 379 camera trapping photo events (2,196 photos) gathered in natural canopy bridges over the course of a year (7,198 trap nights), including information on activity period over the course of the day and over the course of the lunar cycle. We conservatively estimate that 17 individuals were photographed, including one juvenile. Being 900 km away from Iquitos, Peru (the site of the closest record), discovery of this species in the Lower Urubamba constitutes a significant range extension.