Wildfire smoke impacts activity and energetics of wild Bornean orangutans.

Indonesia's peatlands experience frequent and intense wildfires, producing hazardous smoke with consequences for human health, yet there is a lack of research into adverse effects on wildlife. We evaluated the effects of smoke on the activity and energy balance of Bornean orangutans (Pongo pygmaeus wurmbii) in a peat swamp forest at the Tuanan Research Station, Central Kalimantan. We collected behavioural data and urine samples from four adult flanged males before, during, and after wildfires between March 2015 and January 2016. During fires, particulate matter (PM10) concentrations were hazardous. Orangutans increased rest time during and after the smoke period, and decreased travel time and distance and increased fat catabolism post-smoke. The increase in post-smoke ketones was not related to changes in caloric intake and was likely due to an increase in energy expenditure, possibly related to immune response. Results show that wildfire smoke negatively affects orangutan condition, and sustained research is needed to assess the magnitude of the threat to the long-term viability of this Critically Endangered species.

Predicting the frequency of food-related agonism in white-faced capuchin monkeys (Cebus capucinus), using a novel focal-tree method.

Food abundance and distribution have played a central role in the conceptual theory of primate socioecology [Janson, Behaviour 105:53-76, 1988; Isbell, Behavioral Ecology 2:143-155, 1991; Sterck et al., Behavioral Ecology and Sociobiology 41:291-309, 1997; van Schaik, In: Standen V, Foley RA, editors, Comparative Socioecology. Oxford: Blackwell. p 195-218, 1989]. This theory predicts that agonistic ("contest") competition should occur when food is distributed in discrete, defensible patches; in contrast, when food sources are distributed uniformly or randomly, non-agonistic ("scramble") competition is expected. Primatologists usually measure resource density and patchiness from a botanical perspective, ignoring the biology of the animal being studied. Such an approach may be irrelevant in terms of how animals view the dispersion of resources. Using a novel focal-tree method that measures resource availability on a scale that is both spatially and temporally relevant to the animal under investigation, we take a cost-benefit approach to predict the frequency of food-related agonism in white-faced capuchin monkeys (Cebus capucinus) from 11 ecological and social variables. We retained four variables in the regression model: two representing the opportunity for aggression (i.e., feeding bout length and the number of feeding adult females), and two representing opportunity costs (i.e., fruit abundance and the number of potential feeding sites in the focal tree). The results of this study indicate that the amount of food-related aggression in white-faced capuchins can be predicted by variables representing the costs and benefits of contesting a food resource.

Rescue behavior in white-faced capuchin monkeys during an intergroup attack: support for the infanticide avoidance hypothesis.

In this work we report the first published observational evidence of rescue behavior during an intergroup interaction in white-faced capuchin monkeys (Cebus capucinus). The study groups (groups AA and RR) inhabit the forest of Lomas Barbudal Biological Reserve in Guanacaste, Costa Rica, and have been under investigation since 1990 and 1997, respectively. Here we report a single interaction in which a victim mother-infant pair was rescued from potential injury or death by the intervention of an adult male from their social group during an intergroup encounter. We discuss several hypotheses that may be relevant in explaining this unique observation.

Polymorphism of visual pigment genes in the muriqui (Primates, Atelidae).

Colour vision varies within the family Atelidae (Primates, Platyrrhini), which consists of four genera with the following cladistic relationship: {Alouatta[Ateles (Lagothrix and Brachyteles)]}. Spider monkeys (Ateles) and woolly monkeys (Lagothrix) are characteristic of platyrrhine monkeys in possessing a colour vision polymorphism. The polymorphism results from allelic variation of the single-locus middle-to-long wavelength (M/L) cone opsin gene on the X-chromosome. The presence in the population of alleles coding for different M/L photopigments results in a variety of colour vision phenotypes. Such a polymorphism is absent in howling monkeys (Alouatta), which, alone among platyrrhines, acquired uniform trichromatic vision similar to that of Old World monkeys, apes, and humans through opsin gene duplication. Dietary and morphological similarities between howling monkeys and muriquis (Brachyteles) raise the possibility that the two genera share a similar form of colour vision, uniform trichromacy. Yet parsimony predicts that the colour vision of Brachyteles will resemble the polymorphism present in Lagothrix and Ateles. Here we test this assumption. We obtained DNA from the blood or faeces of 18 muriquis and sequenced exons 3 and 5 of the M/L opsin gene. Our results affirm the existence of a single M/L cone opsin gene in the genus Brachyteles. We detected three alleles with predicted lambdamax values of 530, 550, and 562 nm. Two females were heterozygous and are thus predicted to have different types of M/L cone pigment. We discuss the implication of this result towards understanding the evolutionary ecology of trichromatic vision.