A study on the food, foraging and flight height in three species of pteropodid bats, namely Cynopterus sphinx, Rousettus leschenaultii and Pteropus giganteus was conducted in Tirunelveli and Tuticorin districts of southern Tamil Nadu, India. A total of 37 species of plants were identified as potential food plants of the pteropodid bats. The preference for fruits by pteropodids varied according to the developmental stages of fruits namely, immature, unripe and ripe. There is a relationship between the foraging activities of bats and the moon phase. Bats exhibit a varied foraging pattern and flight height. A variation in the foraging flight height was observed in C. sphinx and R. leschenaultii. R. leschenaultii was observed to have a higher foraging echelon than that of the C. sphinx. In our study we found that the C. sphinx forages normally at canopy level (up to 3.5m), R. leschenaultii forages at upper canopy levels (up to 9m) and P. giganteus at a height above the canopy area (>9m).

a b s t r a c tIn this study, we investigated the genetic social structure of a polygynous fruit bat, Cynopterus sphinx. We tested whether colonies of C. sphinx are substructured and if genetic relatedness among group members is non-random. Although we did not find statistical evidence of genetic structuring of harems within a colony, significant levels of inbreeding within colonies and social associations between related individuals were observed. The average pairwise relatedness was higher for females within a harem (average: 0.02) than within the colony (average: −0.03) (p < 0.005). In most harems, the harem male was highly related to one harem female (with an average relatedness of 0.2). Further, statistical resampling suggested that this association is non-random, potentially suggesting mate selection. Although the average relatedness among males in colonies was zero, the range of relatedness (−0.43 to 0.49) was high. We conclude that colonies, to some extent are inbred units, comprising of both related and unrelated individuals, and that social associations might be kin based.

We used radiotelemetry to evaluate relationships between female Cynopterus sphinx and their young during the late lactation and weaning periods. Our observations suggest that young C. sphinx may be tutored by their mothers during this period. Before young are weaned, females intermittently visit their young during nightly feeding bouts. During the weaning period, mothers forage near their day roosts and are accompanied by or forage near their young. We suggest that observational learning during the late lactation and weaning period occurs when young C. sphinx accompany their mothers on foraging flights. Thus, young bats may have an opportunity to learn the location of profitable food patches.

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