A comparative study of the diet of the Indian Eagle Owl Bubo bengalensis (Franklin, 1831) from two distinct habitats in the Tamil Nadu - Puducherry area, southern India

Abstract

A total of 166 prey items were identified from pellets, pellet remains and prey remains – 84 from Arunachala Hill and 82 from Pondicherry University campus. The total biomass encountered from pellet and prey remains was 22,620.17g – 11,240.59g from Arunachala and 11,379.58g from Pondicherry University. Out of the 166 prey items 102 were non-volant small mammals accounting for a biomass of 13,973.90g – 5,616.83g (49.94%) from Arunachala and 8,357.07g (73.42%) from Pondicherry University. Even among these murid rodents dominated – 44.99% in Arunachala and 70.13% in Pondy University. Milvus migrans were predated upon by Bubo bengalensis and 10 partly eaten carcasses were recovered – hence they could not be assigned a category as the quantity consumed could not be determined. It is a well known fact that Eagle Owls are intolerant to other avian predators, and territorial behaviour and intraguild aggression / predation could be responsible for this phenomenon. 3 other partly consumed remains of birds were also encountered and these too could not be assigned a category for the same reason that the quantity ingested could not be determined. Anurans occurred for a combined biomass of 12.87% in both areas. The rest, viz. Coleoptera, Orthoptera and Paratelphusa sp. accounted for a paltry biomass of 0.51%. The difference between murid rodents occurring in the two habitats was illuminating. In Arunachala the constant food of the owls were the field rodents Millardia meltada (15.47%), Bandicota bengalensis (8.74%) and Tatera indica (11.65%), and a single Bandicota indica (6.07%) which is a species found around rural habitations. The first two species were conspicuous by their absence in Pondicherry University and the Tatera indica was encountered in very small quantities (3.70%). Uniquely enough, the terrestrial and fossorial forms of urban rodents formed the basic food of Bubo bengalensis in Pondicherry University – Rattus rattus (20.64%) and Bandicota indica (43.94%). Both these species are human commensals and occur in pestilential proportions in urban habitats. The specific identity of Mus spp. could not be derived due to the complexity of identification, but as our specimens are housed in the repository of WILD molecular analysis could shed light on the species complex in the near future. We have compared non-volant small mammal prey of the regions we studied with those of Maharastra and the results are discussed.