Nestling Development of Ring-necked Parakeets (Psittacula krameri) in a Nest Box Population

Abstract

Chick development of a population of non-native Ring-necked Parakeets (Psittacula krameri) (RNP) has been investigated between 2006 and 2008 in Heidelberg, Germany. In parrots hatching asynchrony is common. RNP chicks are under natural selection to fledge synchronously with their siblings, as parents return less often to the nest after the first chick has fledged and remaining chicks may starve. Female nestlings apparently outperform the males by about one d in body mass gain, but also had higher measurements in tarsus, wing and tail growth. This was unexpected as adult males are generally larger than females. First-hatched chicks showed lowest biometrical values as compared to their younger sib- lings in several characters like body mass gain, bill, wing, and tail length. This feature may contribute to a synchronization of fledging in an otherwise asynchronous brood.