Acta Zoologica Cracoviensia, 44(1) 2001
Issue:
VOL 44(1) 2001
Keywords:
Tawny Owl, Strix aluco, diet, breeding success, rats, Rattus sp.
Download PDFShare this article:
Notes on the diet of successful and failed breeding Tawny Owls (Strix aluco) in urban Rome, Italy
Abstract:
The authors compared the breeding diet of successful and unsuccessful pairs of Tawny Owls in urban Rome to estimate the relative importance of different prey groups to owl reproduction. They identified a total of 3 089 prey items from 15 owl territories. Medium-sized passerines, rats, and Columbidae contributed more than 20% in number and 60% in biomass. Small-sized passerines and rodents were the taxa most preyed on by number (more than 40%), decreasing at the biomass level (less than 30%). Geckos, swifts, and bats made up a minor component of diets, both in number and biomass. Insects constituted more than 20% of diets by number, but their contribution was negligible at the biomass level. Among large-sized prey, both Columbidae and rats were taken more by successful pairs than by unsuccessful ones, but only percentage number and biomass of rats significantly differed among the diets of pairs with different breeding status. The number of prey per pellet and niche breadth showed no substantial difference between the diets of successful and unsuccessful pairs, while mean prey weight and prey biomass per pellet slightly increased in the diets of successful pairs. It is suggested that the relationship between Tawny Owl diet and reproduction may reflect both differences in prey availability and prey selection among territories.
