TROPHIC NICHE OF THE BARN OWL AND LITTLE OWL IN A RICE FIELD HABITAT IN NORTHERN ITALY

We characterized the trophic niche of two syntopic owl species, barn o wl (Tyto alba) and little owl (Athene noctua), which inhabit rice fiel d and water-meadow habitats of northern Italy. Small mammals were the most important prey category for barn owls with 84% of prey, while inv ertebrates (primarily insects) accounted for approximately 55% of litt le owl prey. Small mammals were the staple food of both predators in t erms of relative biomass of prey. Barn owls preyed upon larger rodent species (common rats, water voles), whereas little owls concentrated t heir hunting pressure on wood mice, a medium-sized rodent. Mean weight of small mammals ingested by barn owls (37.7 g) was considerably grea ter than that by little owls (22.3 g). Dietary width was significantly greater in little owl than barn owl diet (2.2 vs 1.4), although the r everse was true for that of width in relation to small mammal prey (8. 5 for barn-owls vs 4.7 for little owls). Niche overlap was considerabl y high (GO = 0.94), but not complete.