Self-anointing in animals

Self-anointing in animals, sometimes called anointing or anting, is a behaviour whereby a non-human animal smears odoriferous substances over themselves. These substances are often the secretions, parts, or entire bodies of other animals or plants. The animal may chew these substances and then spread the resulting saliva mixture over their body, or they may apply the source of the odour directly with an appendage, tool or by rubbing their body on the source.

The functions of self-anointing differ between species, but it may act as self-medication, repel parasites, provide camouflage, aid in communication, or make the animal poisonous.

Several primate species self-anoint with various items such as millipedes, leaves and fruit. They sometimes drool while doing this. Both capuchin and squirrel monkeys perform urine washing, when they deposit a small quantity of urine onto the palm of a hand and then rub it on the sole of the opposite foot. It is thought to have multiple functions including hygiene, thermoregulation and response to irritation from biting ectoparasites (such as ticks and botfly). Some strepsirrhines and New World monkeys also self-anoint the body with urine to communicate.

Wild wedge-capped capuchin monkeys (Cebus olivaceus) self-anoint with millipedes (Orthoporus dorsovittatus). Chemical analysis revealed these millipedes secrete two benzoquinones, compounds known to be potently repellent to insects and the secretions are thought to provide protection against insects, particularly mosquitoes (and the bot flies they transmit) during the rainy season. Millipede secretion is so avidly sought by the monkeys that up to four of them will share a single millipede. The anointment must also involve risks, since benzoquinones are toxic and carcinogenic, however, it is likely that for capuchins, the immediate benefits of self-anointment outweigh the long-term costs. Secretions from these millipedes also elicit self-anointing in captive male and female tufted capuchin (C. apella) and white-faced capuchin (C. capucinus) monkeys.

Wild Cebus anoint more with plant parts, including fruits, whereas wild Sapajus anoint more with ants and other arthropods. White-faced capuchins in particular use more plant species at each site for anointing compared with other capuchins and may specialize in anointing as an activity independent from foraging, whereas most other capuchin species tend to eat the substances they use for anointing. Wild Cebus anoint at a higher frequency than Sapajus as occurs in captive groups. However, contrary data from captive animals there no difference in the range of sociality for anointing between Cebus and Sapajus in the wild.

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