Owl monkeys (Aotus spp.) perform self- and social anointing in captivity

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.