Winning and losing: causes for variability in outcome of fights in male Magellanic penguins (Spheniscus magellanicus)

RENISON D.; BOERSMA P.B.; MARTELLA M. B.

BEHAVIORAL ECOLOGY

OXFORD UNIV PRESS INC

Año: 2002 vol. 13 p. 462 - 466

1045-2249

Game theory models predict that fighting ability should be more important in contest outcome when the payoffs of winningare high for both contestants, and ownership should be more important when payoffs are low. Male Magellanic penguins(Spheniscus magellanicus) provide an opportunity to test these predictions in a natural setting because payoffs of winning arehigher for penguins fighting before egg laying and lower for penguins fighting after egg laying, allowing the prediction ofdifferences in who should win and lose. We watched an area of approximately 2000 Magellanic penguin nests from 1992 to1996 at Punta Tombo breeding colony, Argentina; we quantified fighting behavior, banded contestants, measured their bodysize (here used as an index of fighting ability), determined ownership status when possible, and monitored their reproductivesuccess. We determined that male Magellanic penguins fought for nests and mates. As theory predicts, before egg laying, bodysize difference was more important than ownership as a predictor of contest outcome and fight duration. After egg laying,owners won fights, and size did not predict who won or how long they fought. Our comparisons of nest ownership, nest quality,and chicks fledged by winners and losers suggested that our predictions on the change in benefits of winning before and afteregg laying were correct. We conclude that game theory models are useful in predicting who won or lost fights in male Magellanicpenguins and that ultimate benefits of winning fights are related to fitness