Mistletoes could moderate drought impacts on woodland birds, but are themselves susceptible to drought-induced dieback

Mistletoes are hemiparasitic plants and keystone species in many ecosystems globally. Given predicted increases in drought frequency and intensity, mistletoes may be crucial for moderating drought impacts on community structure. Dependent on host vascular flows, mistletoes can succumb to stress when water availability falls, making them susceptible to mortality during drought. We counted mistletoe across >350,000 km2 of south-eastern Australia and conducted standardised bird surveys between 2016 and 2021, spanning a major drought event in 2018-19. We aimed to identify predictors of mistletoe abundance and mortality and determine whether mistletoes might moderate drought impacts on woodland birds. Live mistletoe abundance varied with tree species composition, land use and presence of mistletoebirds. Mistletoe mortality was widespread, consistent with high 2018/19 summer temperatures, low 2019/20 summer rainfall and the interaction between summer temperatures and rainfall in 2019/20. T...