The response of breeding pairs of Mongolian gerbils to intruders

Abstract

Male and female Mongolian gerbils, Meriones unguiculatus , are known to be aggressive toward unfamiliar conspecifics introduced into their home territories. A longitudinal study of three mated pairs of gerbils was conducted to determine the effect of the female's reproductive state upon the pair's reactions toward male and female intruders. Pairs were observed during 10-min tests with individual male and female intruders and in the absence of an intruder during several pregnancies and lactation periods. Several nonsocial behaviors were depressed in the presence, as compared to the absence, of an intruder. Affiliative and agonistic contacts between mates increased in the presence of an intruder, and agonistic contact between mates was higher in the presence of a male intruder than a female. No other effects of intruder sex were observed. Virtually all contacts between residents and intruders were aggressive and sexual interactions were never observed. The reproductive condition of the female resident had no effect upon their aggressiveness or that of their mates toward intruders. Time spent by females in the nest increased and contact between mates decreased during the lactation period.