Adaptive hatching hypotheses do not explain asynchronous hatching in Brown-headed Parrots Poicephalus cryptoxanthus

  • Stuart Taylor School of Biological and Conservation Sciences, Private Bag X01, University of KwaZulu-Natal, Pietermaritzburg 3209, South Africa; Current address: Department of Conservation Ecology and Entomology, Private Bag X1, University of Stellenbosch, Matieland 76
  • Michael R Perrin School of Biological and Conservation Sciences, Private Bag X01, University of KwaZulu-Natal, Pietermaritzburg 3209, South Africa

Abstract

At the core of the suite of adaptive hatching hypotheses advanced to explain asynchronous hatching in birds is the assumption that if food is not limited then all the hatchlings will develop normally to adulthood. In this study Brown-headed Parrot Poicephalus cryptoxanthus chicks were hand fed and weighed on a daily basis. Their respective masses were compared using a reparamatised Richards growth model. The results show that although the second and third hatched chicks initially grow faster than the first, the final mass attained by the third chick is significantly less than either of its siblings. Adaptive hatching hypotheses do not explain this result. We propose that the third chick is opportunistic and that is has evolved as insurance against prior chicks surviving because of interspecific pressure on the breeding biology of the species.

Ostrich 2008, 79(2): 205–209
Published
2008-10-24
Section
Articles

Journal Identifiers


eISSN: 1727-947X
print ISSN: 0030-6525