Hunting strategies by Siberian Jays Perisoreus infaustus on wintering small rodents

Sammendrag

The Siberian Jay Perisoreus infaustus, the smallest of west Palearctic corvids, is year-round resident, territorial and stores food prior to the winter. I studied the species’ hunting strategies on small rodents from November through March during 2004–2015 in a subalpine mixed forest in central Norway. Along a fixed track of ca. 5 km, I recorded where a flock of Siberian Jays was first observed. In years when small rodents (mainly bank voles Myodes glareolus) were abundant, the birds were most often seen in trees near open areas with numerous tracks of rodents, and mainly within the forest in years with low rodent abundance. In cold days, i.e. with ambient temperature below –10 oC, very few tracks of small rodents were registered in the snow despite high rodent abundance, and the birds then stayed within the forest. Siberian Jays apparently often stay near open areas hunting for small rodents running in the snow in years with a high rodent abundance, but keep more within the forest in years with low rodent abundance or in cold weather when the rodents live below the snow surface.