Diet of the Barn Owl (Tyto alba) in Ocoyoacac, Estado de Mexico

Abstract

I studied the feeding habits of the Barn Owl (Tyto alba Strigiformes) in Ocoyoacac, State of Mexico (Mexico) in 2012. On such occasion, its diet was analyzed based on the description of the mass of undigested parts of preys in 732 pellets collected. For such description I resorted to Margalef, Simpson, Shannon-Wiener and Pielou diversity index showing the diversity of preys on which the Barn Owls fed. Based on Levin’s standardized trophic niche index the food niche breadth was estimated as well as the correlation between pellet dimensions and the number of eaten preys. Small mammals were the most frequent source of food, followed by arthropods and birds. The dominance of small mammals was relatively low (λ = 0.20). Rattus rattus was the species most frequently consumed, followed by four other rodent species associated with an abundant frequency of consumption (Microtus mexicanus, Reithrodontomys microdon, R. megalotis and Peromyscus maniculatus). Shannon-Wiener index value (H’ = 1.85) and Levin’s standardized trophic breadth index (Bst = 0.42) showed a relatively low uniformity and a selective tendency in the consumption of small mammals. The diet of the Barn Owl showed that the consumption of arthropods was relevant, including arachnids. A selective tendency was observed in the consumption of birds. The significant correlations between the dimensions of the pellets with the number of preys consumed were discussed. The results show that the Barn Owl plays an important role in the biological control of native and non-native rodents of the region.

Keywords

• depredador-presa, control biológico, nicho trófico, tyto alba, área urbana.