Chapter 8 - Nest-sites

Abstract

Publisher Summary This chapter discusses the nest sites of birds. Limitation by acceptable nest sites is evident mainly in species that use special places, such as tree cavities or cliff ledges. The evidence is partly correlative, in that variations in breeding density, from place to place or year to year, often parallel similar variations in nest site availability. Breeding pairs are generally absent from areas that lack nest sites, which seem suitable in other respects (nonbreeders may live there). More convincingly, however, experimental manipulations of nest-site numbers have often led to corresponding changes in local breeding densities. Where nest sites are scarce, the process of density limitation depends on defense of the nest site or of the territory containing it by the pair in occupation, so that the other pairs are excluded. In species that defend a little more than the nest site itself, such as the Starling, Sturnus vulgaris, or Pied Flycatcher, Ficedula hypoleuca, breeding density can have a fixed ceiling, set by the number of sites and regardless of the numbers of contenders.