Partial migration in Australian landbirds: a review

Partial migration is a phenomenon in which some individuals of a species are migrants while others are residents. This paper employs the most current information available to provide an overview of the Australian landbird migration system and the occurrence of partial migration. An extensive review of the literature showed that migration occurs in almost 40% of landbird species breeding in Australia, with a large proportion of these containing both migrant and resident populations. Partial migration is found in 44% of 155 non-passerine species and 32% of 317 passerine species examined. Such high proportions of species that are partially migratory are consistent with the suggestion that partial migration is particularly common in austral bird species. The existence of migrant and resident individuals within single populations has not been identified for most species, and the Silvereye, Zosterops lateralis, is the only partially, migratory species for which reliable information on percentages of the recaptured population are available. Available evidence suggests that populations with resident and migrant elements are prevalent throughout much of Australia. An understanding of partial migration has important ecological and conservation implications.