Incubation status and nestling periods in hole-nesting passerines in Finnish Lapland

Abstract

In northern Finnish Lapland (about 69°03'N, 20°50'E) the mean incubation period was 14.6 days (n = 113) in the Pied Flycatcher Ficedula hypoleuca, 14.8 days (n =47) in the Redstart Phoenicurus phoenicurus and 14 .8 days (n = 20) in the Siberian Tit Parus cinctus. The corresponding figures for the nestling period were 15 .6 (n = 50), 13.5 (n = 22) and 18 .8 (n =12). The means did not deviate markedly from publishedrecords further south. The interspecific differences in the relative variability (CV%) ofthe incubation period were significant and in the Pied Flycatcher and the Redstart the incubation period varied more than the nestling period . CV% of the incubation and nestling period was least variable in the Siberian Tit. In the Pied Flycatcher and the Redstart, hatching success decreased as the incubation period increased. The main factor affecting the duration of incubation in the Pied Flycatcher and the Redstart was the mean temperature during the incubation period, but in the Siberian Tit it was the laying date . The nestling period was not significantly related to any factor .