Communication among hamsters by high-frequency acoustic signals: II. Determinants of calling by females and males.

Abstract

Basal rates of high-frequency vocalization by estrous female hamsters [Mesocricetus auratus] exceeded those typical of nonestrous females. Even higher rates of calling by estrous females were provoked by male odors (male shavings or anesthetized males). This suggests that cues which normally indicate a male''s proximity can increase the rate of high-frequency calls by an estrous female. These findings are consistent with a view of female ultrasounds as sexual advertisements which indicate the locations, sexual receptivity and relative passivity of estrous females to nearby male conspecifics. Male hamsters also produced ultrasounds at rates that seemed to depend on the availability of potential mates. Brief exposure to an awake female stimulated male calling; estrous females provoked higher call rates than did nonestrous females. Exposure to anesthetized females also increased the rate of male calling, which suggests that the stimulation of male calling by awake females depends in part on female odors. Both male and female ultrasounds are parts of a communication system that facilitates reproduction by helping to coordinate social behavior with endocrine state.