Nuthatch Sitta europaea Demography, Beech Mast, and Territoriality

Abstract

Population size, local survival and territoriality of Nuthatches were studied in two years with and two years without beech mast, with additional data from a fifth year with presumably no mast. Population size was not larger in summers preceding autumns with beech mast than in summers followed by no mast. Local survival in autumn was higher in beech mast years for juveniles, but not for adults, and the effect of beech mast was more pronounced in juveniles occupying territories with beeches. Local winter survival was not higher in years with than in years without beech mast. The size of the autumn population seems to be adjusted to the food supply through higher rates of starvation or emigration of juveniles occupying low-quality territories in years without beech mast, and not by defence of larger territories.