The role of individual recognition by odors in the social interactions of the Mongolian gerbil (Meriones unguiculatus).

Abstract

This study attempts to determine the importance of individual recognition by odors in the social interactions of male Mongolian gerbils (Meriones unguiculatus). The first experiment tested the effects of anosmia on social interactions. Twentyfour pairs of male gerbils were divided into two groups (experimental and control). Experimental animals were made anosmic by bathing their nasal mucosa with 7% solution of ZnSO4. Control animals were treated with distilled water. Following treatment, control and experimental animals were tested with both familiar and unfamiliar conspecifics, and the frequency and types of social behaviors were compared. The results showed that anosmic animals apparently cannot distinguish between familiar and unfamiliar conspecifics and, therefore, that they treat all other gerbils in the same manner that they treat familiar animals. Control animals, on the other hand, showed significant differences in the frequency and types of behaviors directed towards familiar and unfamiliar conspecifics. The second experiment tested the effects of unfamiliar odors on social behaviors. Twelve pairs of familiar male gerbils were tested under three conditions : with soiled shavings from their own home cage (own familiar odors), with clean shavings, and with soiled shavings from the cage of an unfamiliar pair of conspecifics (unfamiliar odors). The results showed that gerbils can detect unfamiliar conspecific odors and that the presence of such odors can affect the social behaviors of a pair of familiar animals. Pairs of familiar gerbils showed a high frequency of social interactions when in the presence of their own familiar odors, but a reduced frequency when tested with unfamiliar conspecific odors or with clean shavings. It is suggested that this decrease in social behaviors could have been due to changes in levels of arousal or to competing exploratory responses. These experiments thus demonstrate that individual differences in the biological odors of the Mongolian gerbil play an essential role in the recognition of individuals and in the normal pattern of social behaviors of this species.