TERRITORY IN THE PIED FLYCATCHER MUSCICAPA HYPOLEUCA

Abstract

Summary. The male Pied Flycatcher does not show definite territorial behaviour before finding a suitable nesting‐hole. In species with unspecialized nesting biology, territory is chosen before nest‐site. The restricted number of nesting‐holes is in most areas the main factor limiting population density in the Pied Flycatcher. As the number of nest‐boxes in an area was multiplied, the percentage of returning birds ringed as young rose, whereas that of old individuals did not rise. It is concluded that competition for nesting‐places forces a certain number of young birds to emigrate. As the effect is relatively slight, it is concluded that most individuals emigrate for other reasons. Aggressive display and courtship are briefly described. Since overcrowding is mostly effectively prevented by the restricted number of nesting‐holes, the Pied Flycatcher does not need large territories. As the male's courtship includes a repeated nest‐demonstration, his absence from the vicinity of the nest‐site would be unfavourable. Hence, the territory is small, the male principally defending the nesting‐hole. The Pied Flycatcher's home is his castle. Most male Pied Flycatchers are polyterritorial. The distance between territories held by one male in the same season amounted at most to 2–3 km. Polygamy is briefly described. The pre‐requisite of the male's polygamy is in most cases polyterritoriality.