Estimating flying-fox mortality associated with abandonments of pups and extreme heat events during the austral summer of 2019–20
Matthew Mo, Mike Roache, Janine M. Davies, Judith Hopper, Hugh Pitty, Natalie Foster, Sandra Guy, Kerryn Parry-Jones, Geoff Francis, Audrey Koosmen, Leah Colefax, Chelsea Costello, Josie Stokes, Sarah Curran, Michael Smith, Garry Daly, Carla-Maree Simmons, Rhonda Hansen, Desley Prophet, Sara Judge, Fiona Major, Tamsyn Hogarth, Carole-Ann McGarry, Lawrence S. Pope, Stephen Brend, Drew Coxon, Kimberly Baker, Kylie Kaye, Linda M. Collins, M. A. H. Wallis, Rachel Brown, Lisa R. Roberts, Susan Taylor, Tim Pearson, Tania Bishop, Pauline Dunne, Kylie Coutts-McClelland, Lorraine Oliver, Chris Dawe, Justin A. Welbergen
Abstract
Mass mortalities in flying-foxes occur in summers that reach extremely hot temperatures. In this study, we examine the spatiotemporal distributions of mortality from pup abandonments and extreme heat events in Australian flying-fox camps during the 2019–20 summer. We recorded data on flying-fox mortality in known affected camps and applied a standard method to estimate the number of deaths. Pup mortalities from abandonments were recorded in 10 camps in New South Wales. A minimum estimate of 2612 flying-foxes died in pup abandonments, the majority of which occurred in one camp in Bomaderry. Die-offs from extreme heat events were recorded in 40 camps associated with eight separate heat events in south-eastern Australia. A minimum estimate of 72 175 flying-foxes died during these heat events, which all occurred within the range of the threatened grey-headed flying-fox (Pteropus poliocephalus). Further, 409 and 2251 live flying-foxes were taken into care from pup abandonments and heat events respectively. The minimum mortality estimated represents the highest recorded mortality of Australian flying-foxes within a single summer. This highlights a need to restore vegetation in flying-fox foraging areas and camps, address anthropogenic climate change and gather more empirical data to inform heat stress interventions to minimise flying-fox mortalities.