VIGILANCE BEHAVIOR DURING THE BIRTH AND LACTATION SEASON IN NATURALLY-OCCURRING RING-TAILED LEMURS (LEMUR CATTA) AT THE BEZA-MAHAFALY RESERVE, MADAGASCAR

I examined the vigilance behavior of adult males and females in two gr oups of ring-tailed lemurs (Lemur catta) during the birth and lactatio n season at the Beza-Mahafaly Reserve, southwestern Madagascar. I foun d no sex difference with respect to the rates of overall vigilance, ra tes of vigilance toward a potential predator or unfamiliar sound, or r ates of vigilance toward conspecifics from other social groups, nor we re there sex differences in the percentage of time spent vigilant in a ny of the above categories. Higher-ranking females were vigilant signi ficantly more often toward predators or potential predators than lower -ranking females were. I detected no relationship between vigilance be havior and dominance rank among adult males. The alpha female in each group exhibited significantly more vigilance behavior than all other m embers of her group. If was predicted that males should exhibit more v igilance behavior than females do, particularly during the birth and l actation season, when predator pressure is high, if they are benefitin g females in this respect. I discuss the results in the context of thi s prediction and in terms of how ring-tailed lemur males benefit femal es, and why they may be tolerated in social groups.