Extra-pair fertilizations and paternity defence in house martins, Delichon urbica

DNA fingerprinting showed that 15% of 62 house martin nestlings at study colonies in central Scotland were not related to their putative fathers, and 32% of 19 broods contained at least one extra-pair chick. There was no evidence of intraspecific brood parasitism. Birds were never seen to mate outside nests in the vicinity of nesting colonies, and the single copulation that was observed during this study was a pair mating that took place inside a nestbox. Extra-pair birds were often seen to enter nests, with seven of eight identified intruders being males from other nests where laying had already taken place. Pair males mate guarded by ensuring that females spent very little time alone at the nest from about 7 days before the first egg of the clutch was laid, and by accompanying females on up to 70% of flights away from the nest during the 4-5 days before laying commenced. Mate guarding seemed to slacken after egg laying began, with a gradual transition to incubation behaviour taking place. Associated with this was a higher likelihood that the youngest nestling would be fathered by an extra-pair male. Male removal experiments indicated that extra-pair birds were more likely to enter the nest of a fertile female when the pair male was absent, but in three cases where DNA fingerprints were obtained male removal during the fertile period of the pair female had no apparent influence on paternity. © 1995 The Association for the Study of Animal Behaviour.

Duke Scholars

Author Royston Edwin Carter Engineering Graduate and Professional Programs