Nestling feeding-space strategy in Arabian Babblers

Maintaining individual space is a foraging tactic widely used by many adult animals. However, this behavior has not been described for altricial nestl ing birds. In this study, nestling Arabian Babblers (Turdoides squamiceps) defended individual spaces around themselves and obtained food in relation to the size of these spaces. Each nestling created two circular feeding zon es around itself: (1) an internal one (termed exclusive space), within whic h it usually succeeded in preventing nest mates from obtaining food; and (2 ) an external one (shared space), within which the nestling competed for fo od with siblings according to its relative strength. The first indication o f the imminent death of a nestling was when siblings began receiving food i nside its exclusive feeding space. Stability of feeding spaces was tested b y adding a fifth nestling to the nest. None of the exclusive feeding spaces decreased, and feeding rates within them remained constant. In contrast, f eeding rates in the shared feeding spaces diminished as a consequence of th eir reduction in size. It seems that a nestling's survival depends on its a bility to defend its exclusive feeding space. This tactic may enable Arabia n Babbler nestlings to obtain food and survive in their cooperative as well as competitive nest environment in a relatively nonaggressive manner.