Roost and diet selection by Southern Spotted Owlet Athene brama brama (Temminck, 1821) in the Cauvery Delta of Nagapattinam District, southern India

摘要

The Spotted Owlet Athene brama is the commonest among the 62 species of owls of India and also a widely distributed bio-control agent of agricultural pests in India. We studied the roost site selection and diet composition of the Southern Spotted Owlet A.b. brama in the Cauvery Delta in southern India during 2007-08. The roost selection evaluated based on roost site characteristics observed from 22 roost sites revealed that the owlets preferred to roost closer to human habitation than in agricultural fields, with all the roosts found among trees. Albizia saman (Rain Tree) was the most commonly used roost tree species. Tree species with 20-30 m height and 1-3 m gbh were most preferred for roosting due to the presence of a greater number of branches. Roost species and size class selection appeared to depend on availability of suitable locations with better protection from weather and concealment to avoid disturbance from humans and other birds. Diet composition examined through analysis of 55 regurgitated pellets revealed that undigested food items from insects constituted the bulk of the owls diet (57%) followed by mammals (rodents) (24.4%), reptiles (7.8%) and birds (7.3%). However, it is argued that mammals in the form of digestible parts could have contributed more to the diet of the owlet than any other taxa. Higher consumption of rodents and insects is discussed in the light of reducing agricultural pests; adequate roosting sites (mature trees) and creating awareness among the local community about the role of Spotted Owlets will improve their population and help control agricultural pests more effectively.