Predation òn small mammals by tawny owl and comparison with barn owl in the Farma valley (Central Italy)

Abstract

The diet of the tawny owl and the barn owl’s, both dwelling in the Farma Valley (Tuscany) has been studied. These two strigiformes prey upon about the same micromammal species (which make up over 95% of their diets), although in different proportions. The barn owl is more microphagous than the tawny owl. Comparison with the barn owl’s diet in other sites in Central Italy brings to light that the tawny owl’s trophic niche, generally, is quite different from the born owl’s, however two niches may in some way overlap, when the barn owl is roosting near wooded areas, thereby further substantiating the euryphagy of the barn owl. During winter, the tawny owl’s diet is characterized by the crocidurinae shortage and the abundance in typically sylvan preys (Sorex minutus, Clethrionomys glareolus); during late spring sylvan preys, may be on account of the forest lesser accessibility, decrease in number, whereby the tawny owl’s trophic niche appears to converge towards the usual barn owl’s niche. In summer, however, the barn owl seems to predate upon crocidurinae above all, and hence full overlapping of the niche perhaps never occurs. The marked diversity repeatedly found in the samples of small mammals preyed upon by both these strigiformes, and their high trophic levels are well in keeping with other naturalistic approaches highlighting the ecological stability of the zone studied by us, which must therefore be protected. © Taylor & Francis Group, LLC.