Population genetics informs the management of a controversial Australian waterbird

Widespread degradation across Australia’s inland wetland network has contributed to severe declines for many waterbird species. In contrast, breeding colonies of the Australian white ibis (Threskiornis molucca) have increased in urbanised areas along the coast, but the level of dispersal and gene flow between inland and coastal areas remain unknown. This study uses single nucleotide polymorphisms (SNPs) to ascertain the variables influencing genetic connectivity among several inland and urban colonies of white ibis across south-eastern Australia between 2015 and 2018. The contemporary effective population size was estimated, and this value was used in simulations to evaluate the impact of various management scenarios on future genetic diversity. We found no significant differences in allele frequencies between localities, or robust evidence of site fidelity, therefore suggesting widespread dispersal and gene flow between inland and urban colonies. Furthermore, effective sizes were large enough to maintain genetic diversity into the future under various realistic management scenarios. However, the lack of genetic partitioning found suggests that urban management of the ibis should not be undertaken in isolation of the conservation requirements of inland colonies.