Nares occlusion eliminates heterosexual partner selection without disrupting coitus in ferrets of both sexes.

Using an airtight Y maze and a new method to induce peripheral anosmia in ferrets, we assessed the contribution of conspecific odors, either alone or in combination with visual and auditory signals, to heterosexual partner preference. Sexually naive ferrets were gonadectomized and treated with sex steroids, after which their nares were either bilaterally occluded using dental impression material or were sham-occluded. Behavioral and histological evidence suggested that nares occlusion blocked access of odors to the main olfactory epithelium for the duration of the study. Sham-occluded females and males preferred to approach odor only or odor plus visual plus auditory cues from opposite-sex conspecifics, whereas nares-occluded ferrets approached opposite- and same-sex cues equally. All ferrets subsequently mated successfully in tests conducted in a small chamber. When retested in the Y maze, sham-occluded females and males again preferred to approach odor-only or odor plus visual plus auditory cues from opposite-sex ferrets, whereas nares-occluded subjects showed no such preference even in tests when a brief physical interaction with tethered stimulus ferrets was allowed after each trial. Our results show that in the ferret, a carnivore, the detection and processing of volatile odors from conspecifics by the main olfactory system is required for heterosexual mate choice.