Drought in south-west Australia links to urban immigration across multiple avian taxa

Abstract

Background Urban areas are a significant and rapidly expanding part of the global landscape. Urban expansion occurs alongside climate change, with both linked to declines in native species. However, urban environments can offer alternative resources during extreme climatic events such as droughts. Aims We sought to identify bird species that had an increased presence in the major urban center of south-west Western Australia during a climate anomaly characterized by record low rainfall and high temperatures. Methods Using eBird data, we analyzed changes in the reporting rates of all bird species in the period from January 2019 to August 2024. Generalized linear models were used to assess the influence of cumulative 6-month, 12-month, and 18-month rainfall on species reporting rates. Key results Reporting rates increased dramatically (up to nine times higher than average) around the time of the drought, before reducing back to the average once the drought was broken for four species: (1) the black-shouldered kite; (2) the black-tailed native-hen; (3) the tawny-crowned honeyeater; and (4) the western spinebill. Cumulative 6-month rainfall was a strong predictor for the raptor and the two honeyeaters. Other similar species showed no significant change in reporting rate, suggesting the effect is highly species dependent. Conclusions Multiple different types of birds may utilize urban areas during drought events. Further research is needed to identify what drives movement of wildlife in response to such events, and the type of urban resources the birds are using. Implications Urban ecosystems should be integrated into broader conservation plans to support species through the interacting challenges posed by climate change and urbanization.