Spacing behavior of the middle spotted woodpecker in central Europe

Knowledge of the ranging behavior and spatial requirements of a species is fundamental for establishing meaningful conservation strategies. Such infor mation is lacking for the middle spotted woodpecker (Dendrocopos medius), a species endangered throughout its westpalearctic range. By radiotracking, we studied spacing behavior of this habitat specialist in a lowland oak for est of northeastern Switzerland from 1992-1996. Home range and core area si ze decreased from winter to late spring, with males and females having home ranges of similar size. Overlap of male home ranges was highest in winter (up to 40%) and lowest in late spring, whereas core area overlap remained l ow. For both home ranges and core areas, overlapping parts were used random ly in winter but more often than expected in early spring. Overlap of femal e ranges and of core areas did not change from early to late spring, and th e shared parts of these home ranges were used as expected in both seasons. Aggressive interactions were most common in March and April and occurred ma inly between individuals of the same sex. Our results suggest that the midd le spotted woodpecker is not territorial in winter but defends nearly exclu sive territories during spring, with both sexes participating to similar de grees in territorial defence. Based on this seasonal territoriality, we pro pose consideration of cure areas in early spring (Mar and Apr) as a reliabl e estimate of the area requirements of the species to be used in management plans.