Postfledging family space use in great tits in relation to environmental and parental characteristics

Parental care has been widely studied in birds and mammals, but variation in space use in family groups has received less attention, despite its potential importance for both survival and subsequent dispersal of offspring. In this study, we evaluate factors affecting postfledging family space use in a small territorial songbird, the great tit (Parus major). Family space use was monitored using radio tracking. Our main objectives were 1) to quantify in detail the temporal and spatial scale of family movements, 2) to test behavioral hypotheses explaining when and how frequently families leave their breeding territory, and 3) to test to what extent movements were based on familiarity with the environment. We found that variation in space use was to a large extent due to some families, but not others, regularly undertaking foraging excursions of up to more than a kilometer away. Daily excursion probability was higher for families occupying low-quality territories, and consequently, these families covered larger areas during foraging. Excursion behavior and range use also strongly depended on maternal breeding experience and personality. We further present some striking examples of inexperienced mothers moving toward previously visited areas, suggesting that familiarity with the environment plays an important role in patterns of space use. Overall, our results suggest that variation in family movements reflects different foraging strategies in relation to parental characteristics. Copyright 2011, Oxford University Press.