# Contexts of Anointing Behavior in a Group of Blond Capuchin Monkeys (Sapajus flavius) Inhabiting an Atlantic Forest Fragment

## TL;DR

Blond capuchin monkeys use millipedes to anoint themselves, possibly to repel parasites, with adult males being more active in this behavior.

## Contribution

The study identifies millipede species used in anointing and suggests a multifunctional role including self-medication and social interaction.

## Key findings

- Anointing occurred at a rate of 8 episodes every 100 hours of observation.
- Adult males were more actively engaged in anointing bouts compared to other group members.
- Anointing is likely multifunctional, involving self-medication, opportunity, and social interaction.

## Abstract

Parasitism is one of the primary causes of biotic stress in several taxa, and behaviors resembling self‐medication have been documented in numerous species. Anointing involves the application of chemical substances derived from animals, plants, mud, soils, and minerals, often emitting a pungent odor, onto an animal's body. We examined the circumstances surrounding 34 bouts of anointing with millipedes in a group of blond capuchin monkeys (Sapajus flavius) inhabiting an Atlantic Forest fragment in northeastern Brazil. Over 412 h of observation, we collected behavioral data through photographs, video recordings, and ad libitum field notes. We collected and identified the millipedes to the species level. We tested three non‐mutually exclusive hypotheses on the function(s) of this behavior: self‐medication, social bonding, and opportunistic use. We analyzed data in R using nonparametric tests due to low sample size. Anointing occurred at a rate of 8 episodes every 100 h. Millipedes used during anointing are from species that produce benzoquinone. The behavior was more frequently observed in the inferior strata, during midday, while the group is mostly foraging, in periods of higher rainfall, when millipedes emerge from the ground, and during the high fruit productivity season, when the capuchins' activity budget is less constrained. Although anointing occurred at similar rates in solitary and social contexts, adult males were more actively engaged in anointing bouts, indicating sex difference in this behavior, and a possible social function. The observed pattern suggests anointing is a multifunctional behavior, combining elements of self‐medication, opportunity, and social interaction.

Wild blond capuchin anoints with millipede species that secrete a chemical capable of repelling ectoparasites, suggesting a self‐medicative function. Social and solitary anointing bouts occurred at similar frequencies, but with greater engagement by adult males, indicating that anointing is a multifunctional behavior.

We recorded 34 bouts of anointing with millipedes by capuchin monkeys at a rate of 0.08 bouts per contact hour.Similar rates of solitary and social anointing, but adult males were more engaged in bouts.Anointing is a multifunctional behavior, combining elements of self‐medication, opportunity, and social interaction.

We recorded 34 bouts of anointing with millipedes by capuchin monkeys at a rate of 0.08 bouts per contact hour.

Similar rates of solitary and social anointing, but adult males were more engaged in bouts.

Anointing is a multifunctional behavior, combining elements of self‐medication, opportunity, and social interaction.