Initial winter flock formation in the Willow Tit Parus montanus. Do immigrating juveniles assess the quality of territorial adults?

Abstract

In the Willow Tit Parus montanus, forming of winter flocks starts shortly after the juveniles have become independent of their parents. In the early phase of flock formation the juveniles roam about prospecting for suitable winter territories. They visit several occupied territories in succession and seek contact with the territory holders. I describe the behaviour of juveniles during such encounters with adult conspecifics. I suggest that, by approaching adults closely and behaving specifically, juveniles gain important information on the adults' innate qualities; this may affect the settling juveniles' future survival.