A case of alloparental care in the South Island Robin (Petroica australis): Accidental adoption or kin selection?

Abstract

ABSTRACT It has been suggested that a high degree of relatedness could explain the occurrence of alloparental care in birds, but few studies have confirmed if there is a genetic relationship between foster parents and chicks. Using one case of adoption involving allofeeding and allodefense of a South Island Robin (Petroica australis) fledgling by a neighboring male, we assessed whether the adoption was the result of close kinship, care directed to offspring from an extra-pair copulation, or altruistic behavior toward non-kin. Our genetic analysis showed that the foster father was not the adopted fledgling s biological father, nor was he closely related to the chick. We conclude that his altruistic behavior may have been accidental, driven by a breeding male encountering the begging of an unrelated chick that had moved into his territory. The low level of adoption in this population (1.5% of 65 chicks) also supports the hypothesis that alloparental care in South Island Robins is likely to be the result of errors in kin recognition.