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Gilson, Lauren N. – Behavioral flexibility in juvenile ospreys. 1996.

juvenile OspreyI investigated the post-fledging behavior of juvenile ospreys (Pandion haliaetus) at Cascade Lake, Idaho after learning that osprey fledglings in colonial or semi-colonial breeding aggregations may move between nests once they begin to fly. Was this a fortunate accident for them- that is, were they landing on other nest platforms by chance, or were they seeking out other nests, as a behavioral tactic through which to better their own chances of survival post-fledging? Fledglings take a behavioral risk when they forego parental protection and provisioning of their natal nests to explore nests other than their own. Is there a payoff to taking such a risk at such an early age? I manipulated brood size to test this notion, and found that nest switches arose from all of the multiple-fledgling broods, but only two of the single-young broods, and that dominant brood members did not switch, but single chicks that switched nests had received poor parental provisioning prior to fledging did. Thus it appeared that fledgling ospreys exhibited switching as a behavioral tactic in response to parental provisioning and their dominance status among siblings.

Thesis Abstract

Where Are They Now? 


Gilson, L.N. and J.M. Marzluff. 2000. Facultative nest switching by juvenile Ospreys. The Auk 117(1):260-264.