Foraging behaviour and habitat use in corvids wintering on farmlands in northern Italy

Rolando A., Peila P. & Marchisio M.



Abstract:

Foraging behaviour and habitat use of corvids (Hooded and Carrion Crows, Rooks, Magpies) wintering on farmlands have been studied in the western Padana Plain (northern Italy). All species foraged prevalently on meadows and maize stubbles. Differences in the proportions of use of crops were not significant between Hooded and Carrion Crow, whereas they were significant in every other comparison between species. Foraging techniques were opportunistically used according to the foraging habitat choosed. Surface pecking was the commonest technique for every species, while digging was often displayed by the Rook only. Feeding rates varied according to the crop types used. Rooks fed significantly quicker than others on dunged meadows and harrowed fields, whereas Magpies fed slower than others on maize stubbles. The highest feeding activity of the Rook was obtained by means of an unremitting pecking activity and a wide use of all the different foraging techniques. No significant difference in feeding rates was found between Hooded and Carrion Crows. Both habitat use and foraging behaviour changed from area to area, suggesting that foraging ecology of corvids largely depends upon local environmental conditions. Flocks of Hooded Crows and Rooks were significantly more numerous when Carrion Crows and Hooded Crows were present, respectively. However, these data may be interpreted without assuming that interspecific competiton affects flock size.