Sexual dimorphism in foraging behaviour of the Great Spotted Woodpecker Dendrocopus major during winters with rich crops of Scotch pine cones

Abstrakti

During the winters of 1990-1991 and 1991-1992, when rich crops of Scotch pine cones were observed, the foraging behaviour of male and female Great Spotted Woodpeckers was studied in the Wielkopolski National Park, in western Poland. Fourteen foraging characteristics were distinguished. Aggressive behaviour was observed only rarely . During both winters the exclusive male and female territories probably did not exist, or were very small and close to one another. Both sexes fed mainly on pine cones and microhabitat utilization and foraging behaviour patterns were generally similar. However, significant differences were found in almost all aspects of male and female feeding niches . Males, more than females foraged on cones and their foraging behaviour was more stereotyped. Females used a greater spectrum of microhabitats and techniques, and were more mobile than males. This was probably a consequence of male social dominance, which influenced the females to feed more often on alternative food. These differences are thought to be a result of less defined territories due to a temporarily richer food supply.