The effect of habitat loss on a deciduous forest specialist species:: the White-backed Woodpecker (Dendrocopos leucotos)

The White-backed Woodpecker (Dendrocopos leucotos), one of the rarest European woodpeckers, is an old-growth deciduous forest specialist which has shown widespread decline over most of its distribution range. In this study, I extend earlier analyses concerning range contraction and explore whether there exists a threshold in the amount of suitable habitat below which the species will not persist, and if there is a nonlinear decline in population size as suitable habitat in the forest landscape is reduced. A metapopulation model was parameterized with data from a stable population and an analytical estimated extinction threshold was tested on two data sets on population decline and range contraction. The species disappears from regions when the amount of deciduous forest declines below a certain level. One isolated Swedish sub-population, which had withdrawn to a forest-landscape with resources below the habitat threshold, became extinct in 1996. The two other Swedish sub-populations are in forest landscapes below the minimum habitat threshold and both these populations are declining. Finnish sub-populations persist in a landscape below the habitat threshold, however. Reanalyzing data for Finland indicates a time delay in population response as habitat is destroyed and when the amount of suitable habitat falls below 10% there is an accelerated decline in population size; Tn today's intensively managed forests in Sweden and Finland, with low proportions of suitable habitat in the forest landscape, the immediate danger for the species is that the population will suffer from isolation. (C) 2000 Elsevier Science B.V. All rights reserved.