Timing of breeding in subarctic passerines in relation to food availability.

摘要: We studied timing of breeding in four species hole-nesting passerines, the Siberian tit (Poecile cinctus), great (Parus major), pied flycatcher (Ficedula hypoleuca), and redstart (Phoenicurus phoenicurus), abundance arthropods their diet (ground-dwelling spiders, winged insects, foliage-feeding lepidopteran hymenopteran larvae) Finnish Lapland for 6-12 years. Densities invertebrate groups varied considerably, both seasonally annually. All bird started to breed early summer, when weather conditions were often poor. At beginning season all relied on ground-dwelling whose abundances peaked less variable over years than those insects. Abundances emergence caterpillars birch pine canopies (the major food sources foliage-gleaners) highly variable, but each year July or August, after nestling period birds. This contrasts with r...