Competitive positioning as an indicator of nestling survival in red-cockaded woodpeckers.

Abstract

Nestling behavior in five populations of red-cockaded woodpeckers (Picoides borealis) in peninsula Florida from 1997–2003 and 2007 revealed novel mechanisms and behavioral positioning of crossed, disproportionately long necks in all nestlings (Stage I, 10–17 days of age). Nest observations in Stage I showed that the crossed neck behavior occurred in all broods of two or more, and facilitated dominant nestlings to beg sooner, reach higher, and to knock aside their smaller siblings, effectively controlling the central point below the nest cavity entrance. Stage II and III nestlings (11–17 and >18 days, respectively) were generally satiate in the cavity bottom on most occasions. Compared to satiate nests, those with elevated levels of aggressive behavior fledged significantly fewer young. Aggressive positioning behavior, fighting, and pecking occurred in Stage I...