Marginal differences between random plots and plots used by foraging White-backed Woodpeckers demonstrates supreme primeval quality of the Bialowieza National Park, Poland

Abstract

I compared structural characteristics between foraging plots of an endangered European species, the White-backed Woodpecker Dendrocopos leucotos (WbW), and random plots in primeval deciduous stands of Białowieża National Park. I expected that WbW would use plots with higher amount of dead wood in more advanced decay stage, with higher amount of birches Betula spp. and aspen Populus tremula, and with more large trees. Within 50, 0.25-ha plots (25 used by WbW and 25 random) tree-species composition, tree condition, tree diameter at breast height DBH and characteristics of dead trees were measured. WbW and random plots were similar in overall structure; only the volume of fallen timber was significantly larger in WbW than in random plots (65.3 and 47.4 m3/ha, respectively). There was also a tendency for the occurrence of more snags of 11 -20 cm DBH within WbW plots. Thus, the amount of fallen timber might determine WbW choice of the foraging habitat. However, due to the relatively high similarity of WbW vs. random plots, the sections of Białowieża National Park that are covered with old-growth deciduous stands represent high-quality habitat for WbW foraging.