Responses of female bank voles ( Clethrionomys glareolus) to dominant vs subordinate conspecific males and to urine odors from dominant vs subordinate males

Abstract

Dominant and subordinate male bank voles from stable hierarchies were used as choice objects and urine donors in tests with estrogen-treated females. In a two-choice male preference test 12 out of 15 females reliably showed a preference. All 12 preferred the dominant male. In a two-choice odor preference test the females were presented with equal quantities of normal elimination urine from dominant and subordinate males. Thirteen of fifteen females tested individually showed a preference: Twelve of them preferred the urine of a dominant, over that of a subordinate male. Other females, tested in groups of five, were presented only with the lipid (dichloromethane) fraction of urine. In this case 11 of 12 groups preferred urine lipids of dominant males to urine lipids of subordinates. Cumulative investigation times and frequency of visits were used to determine preferences. The results are discussed with regard to possible causes and biological function. Female preference here represents a case of sexual selection partly by olfaction, and may augment the reproductive success of dominant males.