Is the Eurasian Three-toed Woodpecker Picoides tridactylus a keystone species in boreal forest environments?

The Eurasian Three-toed Woodpecker Picoides tridactylus is a widespread species of the northern Palearctic forests. The species prefers mature coniferous and mixed forests, favouring forests with a good proportion of dead and dying trees. Three-toed Woodpecker has a close connection to forest habitats with natural dynamics and disturbances; it inhabits areas recently disturbed by fire, wind, snow, or other agents that increase the amount of suitable substrate of its insect prey. Its diet consists predominantly of spruce bark beetles (Coleoptera, Scolytidae), although phloem sap of conifer trees is also used especially in springtime. We present here results of both published and unpublished …