Influence of forest structure on the density and distribution of the White-backed WoodpeckerDendrocopos leucotosand Black WoodpeckerDryocopus martiusin Quinto Real (Spanish western Pyrenees)

The nesting areas of 13 pairs of Black Woodpecker (0.41 pairs/km2) and 12 pairs of White-backed Woodpecker (0.38 pairs/km2) were mapped in the Quinto Real forest (Spanish western Pyrenees). Nearest-neighbour analysis indicated a uniform spacing of Black Woodpecker territories and, as both species occupied the most developed beechwoods, White-backed and Black territories showed an aggregated distribution. The local distribution appears to be determined by forest structure. Principal components analysis indicated that forest plots occupied by the woodpeckers had a high percentage of beech in old forest (with a total basal area of tree boles above 20 m2/ha) and with many large trees (diameter at breast height, dbh, over 60 cm).