Competition between the Great Tit Parus major and the Pied Flycatcher Ficedula hypoleuca: An Experiment

Abstract

The experiment was carried out in South Norway from 1975 to 1977 (86 nestboxes in 1977). At the time of egg-laying by the Great Tit Parus major every nest-box was made uninhabitable, by various methods, except those which already contained tit nests. This led to increased efforts by the Pied Flycatcher Ficedula hypoleuca to take over tit nests. They were successful in only two out of 40 cases (one Great Tit's and one Coal Tit's Parus ater, nest) despite a late onset of spring, with delayed laying by the tits. Female flycatchers carried nesting material into another four tit nests. Mutual attacks were frequent and one male flycatcher was killed. Even after the cover of a nestbox had been removed and the entrance hole blocked, the male flycatcher remained singing in the immediate vicinity.