Subordinate Males Sire Offspring in Madagascar Fish-eagle (Haliaeetus Vociferoides) Polyandrous Breeding Groups

The island endemic Madagascar Fish-Eagle (Haliaeetus vociferoides) is one of the most endangered birds of prey. Certain populations in west-central Madagascar sometimes exhibit a third, and sometimes a fourth, adult involved in breeding activities at a nest. We applied DNA fingerprinting to assess relatedness among 17 individuals at four nests. In all nests with young, a subordinate rather than the dominant male sired the offspring. Within-nest relatedness comparisons showed that some dominant males had an apparent first-order relationship with the female. Between-nest relatedness comparisons showed that some adults had an apparent first-order relative at another nest in the study area. Findings that subordinate males contribute to breeding, and that adults in an area may be related, may require conservation measures such as translocation to assure the species' survival.