The relationship between bats and primates, which may contribute to zoonotic disease transmission, is poorly documented. We provide the first behavioral accounts of predation on bats by Cercopithecus monkeys, both of which are known to harbor zoonotic disease. We witnessed 13 bat predation events over 6.5 years in two forests in Kenya and Tanzania. Monkeys sometimes had prolonged contact with the bat carcass, consuming it entirely. All predation events occurred in forest-edge or plantation habitat. Predator-prey relations between bats and primates are little considered by disease ecologists, but may contribute to transmission of zoonotic disease, including Ebolavirus.

Several species of primates, including owl monkeys (Aotus spp.), anoint by rubbing their fur with odiferous substances. Previous research has shown that capuchin monkeys (Cebus and Sapajus) anoint socially by rubbing their bodies together in groups of two or more while anointing. Owl monkeys housed at the DuMond Conservancy have been observed to anoint over the last 10 years, and we report detailed new information on the anointing behavior of this population, including descriptions of social anointing which occurs frequently. We first investigated the occurrence of self-anointing in 35 Aotus spp. presented with millipedes. Detailed descriptions regarding body regions anointed were obtained for all anointers (n = 28). The median duration for a self-anointing bout was 3.6 min (range from approx. 2 s to 14.15 min). While the latency and length of anointing bouts showed considerable interindividual differences, no statistically significant differences were found between sexes, wild- or captive-born owl monkeys or across age groups. However, we found the lower back and tail were anointed at a rate significantly greater than other body parts, but there were no differences in these patterns across sex or wild- or captive-born owl monkeys. More recently, social anointing was investigated in 26 Aotus spp. presented with millipedes, of which half were observed to anoint socially. The average duration for all social anointing bouts was 72.88 s, with a median duration of 30 s (range 5-322 s). A detailed ethogram was also generated that included behaviors that were performed while anointing, including facial expressions and vocalizations. The intraindividual variability for 8 monkeys used in both investigations is discussed. These findings extend our knowledge of anointing and confirm the existence of social anointing in another genus with a unique biology (nocturnal and socially monogamous) distinct from capuchins.

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Owl monkeys (Aotus spp.) are socially monogamous, yet allogrooming is reported to be rare. Because Aotus are nocturnal and arboreal, allogrooming is difficult to observe in natural settings. We observed 21 male-female pairs of captive Aotus nancymaae during 2 nonconsecutive study periods in order to describe the details of allogrooming between mates (partner grooming). We found that grooming bouts are brief and consist of tugging the hair or skin with flexed fingers and/or the mouth. Males groomed females most often, and their rates of partner grooming were negatively related to age. Partner grooming occurred regardless of mating behavior. Camera trap data revealed that the rate of partner grooming (1.50 bouts/h) is greater than that recorded from our direct observations in the early evenings (0.51 bouts/h, in 2013; 0.37 bouts/h in 2003) given that most bouts occurred later in the night. A positive relationship between the rates of the parents' partner grooming and those of their offspring later in life suggests intergenerational transmission. This relationship is influenced by the fathers' rates of partner grooming. We conclude that allogrooming in Aotus is a normal part of their behavioral repertoire that likely serves social functions similar to those in other pair-bonded primates.

Objectives Hair (i.e., pelage/fur) is a salient feature of primate (including human) diversity and evolution—serving functions tied to thermoregulation, protection, camouflage, and signaling—but wild primate pelage evolution remains relatively understudied. Specifically, assessing multiple hypotheses across distinct phylogenetic scales is essential but is rarely conducted. We examine whole body hair color and density variation across Indriidae (Avahi, Indri, Propithecus)—a lineage that, like humans, exhibits vertical posture (i.e., their whole bodies are vertical to the sun). Materials and methods Our analyses consider multiple phylogenetic scales (family‐level, genus‐level) and hypotheses (e.g., Gloger's rule, the body cooling hypotheses). We obtain hair color and density from museum and/or wild animals, opsin genotypes from wild animals, and climate data from WorldClim. To analyze our data, we use phylogenetic generalized linear mixed models (PGLMM) using Markov chain Monte Carlo algorithms. Results Our results show that across the Indriidae family, darker hair is typical in wetter regions. However, within Propithecus, dark black hair is common in colder forest regions. Results also show pelage redness increases in populations exhibiting enhanced color vision. Lastly, we find follicle density on the crown and limbs increases in dry and open environments. Discussion This study highlights how different selective pressures across distinct phylogenetic scales have likely acted on primate hair evolution. Specifically, our data across Propithecus may implicate thermoregulation and is the first empirical evidence of Bogert's rule in mammals. Our study also provides rare empirical evidence supporting an early hypothesis on hominin hair evolution.