Foraging Behavior of Eurasian Three-Toed Woodpeckers (Picoides Tridactylus Alpinus) in Relation to Sex and Season in Germany

Abstract

Abstract I studied year-round foraging behavior of 28 color-banded Eurasian Three-toed Woodpeckers (Picoides tridactylus alpinus) from 1995 to 1999 in Berchtesgaden National Park, Germany. My research focused on how foraging time was divided among various substrates and foraging techniques. Foraging behavior was recorded by instantaneous sampling during independent observation sessions (i.e. foraging bouts). A combination of tapping and pecking was the most important foraging technique used during breeding (>43%) and nonbreeding (>59%). Both mean and maximum foraging bouts (mean ± SD) lasted longer during nonbreeding periods (mean: 17.0 ± 3.7 min, maximum: 61.9 ± 30.2 min) than during breeding periods (4.3 ± 3.0 min, 15.5 ± 16.1 min). Sap-sucking was observed rarely during breeding. Males spent less time foraging on branches, whereas females spent less time in the lower third of trees on which they foraged. Males also manipulated foraging substrates more by pecking and digging (probing), whereas females did more climbing and position-changing on foraging trees. I concluded that Eurasian Threetoed Woodpeckers changed their foraging techniques according to seasonal changes in diet and that, during breeding, males used better foraging grounds than females. Le Comportement de Quête Alimentaire chez Picoides tridactylus alpinus en Relation avec le Sexe et la Saison en Allemagne