Is avoidance by black woodpeckers of old nest holes due to predators?

The breeding success of black woodpeckers, Dryocopus martius, in old and newly constructed nest cavities was compared. Young fledged in only 38% of nests in old cavities compared to 71% in new ones. This difference was mainly due to predation by pine martens, Martes martes. Mean clutch size, brood size, nestling weight and timing of breeding did not differ significantly between old and new nest holes. It is suggested that the reason black woodpeckers usually excavate a new nest cavity each year is mainly to avoid predation but that owing to time constraints some individuals may choose to nest relatively early in an old hole rather than later in a new hole.