Courtship Behaviour in reintroduced California Condors: evidence for extra- pair copulations and female mate guarding

The California Condor Gymnogyps californianus is one of world's most critically endangered birds. Beginning in 1992, reintroductions have sought to re-establish wild populations and recent breeding efforts have allowed the opportunity for intensive study of breeding behaviour. Here, we document for the first time the occurrence of extra-pair copulations and female mate guarding in condors. We studied courtship behaviour from late November through to egg-laying (mid-February to early April) when displays and copulations ceased. We quantified displays and copulations by observing focal males during timed observation periods. Courtship behaviour in condors includes male displays, mounting and copulation. Full displays began up to 124 days prior to egg-laying although early pre-breeding displays rarely led to mounting and attempted copulations. Copulations began up to 25 days prior to egg-laying. Females often solicited displays by approaching and interacting with males. Males usually displayed to extra-pair females when their social mate was out of sight. Where pair females were present, they disrupted such displays or copulation attempts. Although extra-pair behaviour was not previously documented in wild condors, this may have been because in observations biased towards nest sites encounters with extra-pair birds are rare. Alternatively, the propensity for such behaviour may be enhanced in the reintroduced population because of increased opportunity for social interaction related to supplementary feeding, mate incompatibility due to limited mate choice or a high degree of genetic relatedness among mates. Whether condors are genetically monogamous remains to be determined.