Avian community changes following drought-induced canopy collapse in a Mediterranean-type forest

Abstract

Context Extreme drought can result in the widespread die-off of forests and dramatically altered ecosystem structure. Such changes are likly to influence fauna using resouces within these forests. Aims Following a record hot and dry year/summer in 2010/11, large-scale canopy collapse occurred within a Mediterranean-type mixed jarrah (Eucalyptus marginata)–marri (Corymbia calophylla) forest in south-west Western Australia. We investigated the effects of this collapse on bird assemblages in 2016, 5 years after the initial collapse. Methods We carried out bird surveys using a standardised search method for five paired drought-affected and adjacent healthy forest plots. Key results A total of 3042 records of 51 bird species were observed across all surveys. Overall, the pooled (mean ± s.d.) reporting rates for drought-affected plots (13.84 ± 0.60 individuals/survey) were significantly less than the reporting rates for healthy plots (34.44 ± 1.03 individuals/survey) (PERMANOVA: F1 = 54.94, R2 = 0.31, P = 0.001). Species diversity was also higher in healthy plots (t26 = 11.21, P < 0.001). Foliage-searching birds were the most abundant guild across all plots and were reported less often in drought-affected plots (t6 = 2.70, P < 0.04). Conclusions Drought-affected jarrah forest plots exhibited significant differences in bird assemblages compared to healthy plots. Overall, the drought-affected forest provides a less favourable habitat for birds compared to healthy forest. Implications With marked variability and extreme climate events predicted for the future, understanding the impacts of such changes will contribute to how we manage forest ecosystems.