Chemical communication, aggression and sexual behaviour in the owl monkey (Aotus trivirgatus griseimembra)

Abstract

This thesis quantified sexual, aggressive and associated behaviours in captive owl monkeys and examined the importance of olfactory cues in mediating these behaviours. Animals of the same sex showed high frequencies of aggressive behaviour but no sexual behaviour. Subordinate animals tended to exhibit lower levels of scent-marking, although individual variability in this behaviour was pronounced. Evidence was obtained which suggested that arching displays (which occur in several Platyrrhine species) primarily subserve an aggressive function.

The effects of partial anosmia upon intermale aggression were investigated. Anosmia was induced by placing plugs containing bismuth-iodoform paste, as near as possible to the cribriform plate. Males fought less readily and showed less contact aggression when anosmlc. However, intermale aggression was not abolished and presumably other sensory cues are also involved. Anosmia also had subtle effects on other behaviours, eg, olfactory inspections and proximity. Control experiments indicated that the technique employed produced anosmia to conspecific odours and that its effects were not due simply to discomfort.

The effects of partial anosmia upon sexual behaviour of males paired with familiar females were examined. No consistent effects on sexual behaviour were observed. However, the suggestion that ol factory cues may play a role in sexual attractiveness is not discounted.

The ability of owl monkeys living in family groups to discriminate various odour cues was determined. Breeding males showed the greatest response, in terms of sniffing and scent-marking, to conspecific odours, and subcaudal secretion plus urine elicited a greater response than urine alone. It was impossible to demonstrate discrimination of sex or endoctrine status on the basis of odour cues alone. The effect of social factors on responsiveness is discussed.

Histological studies confirmed that patent nasopalatine ducts and vomeronasal organ were present in Aotus and some other primate species. External and histological examinations of the cutaneous glandular complexes in Aotus revealed no sexual dimorphism in these glands, though subspecific differences may exist.