Estimating flying-fox mortality associated with abandonments of pups and extreme heat events during the austral summer of 2019–20

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.

Gammaretroviruses, novel viruses and pathogenic bacteria in Australian bats with neurological signs, pneumonia and skin lesions

“…While mass mortalities of adult and young flying foxes have been associated with periods of extreme heat (16, 17), additional disease syndromes and mass mortality events have recently emerged in Australian chiropterans. Episodic mass pup abandonment has been associated with extreme heat, but also dehydration, nutritional stress, and dam death or desertion (16).…”

“…While mass mortalities of adult and young flying foxes have been associated with periods of extreme heat (16, 17), additional disease syndromes and mass mortality events have recently emerged in Australian chiropterans. Episodic mass pup abandonment has been associated with extreme heat, but also dehydration, nutritional stress, and dam death or desertion (16). Herein, we describe the emergence of several novel disease syndromes in flying foxes, including a distinctive pattern of acute to peracute vascular and inflammatory lung lesions in grey-headed flying foxes and a black flying fox following exposure to stressors such as extreme heat, mass pup abandonment, or traumatic injury.…”

High Prevalence of Beta-Lactam-Resistant Escherichia coli in South Australian Grey-Headed Flying Fox Pups (Pteropus poliocephalus)

“…Consequently, horizontal gene transfer may drive the emergence of new strains of multidrug-resistant bacterial pathogens in the pups' gut microbiome [84]. Given that heat-stress events and pup abandonments are likely to increase in the future due to climate change, there are likely to be increasing numbers of GHFF pups entering care each year [86,87], and many of these will require antimicrobial therapy. Administration of antibiotics to injured or sick GHFF pups carrying antimicrobial-resistant isolates may result in a poor response to treatment and a worsened prognosis for recovery and release back into the wild.…”

Factors influencing persistence of a threatened amphibian in restored wetlands despite severe population decline during climate change driven weather extremes

“…Similar findings point to the impacts of severe weather events on recruitment in other species. For example, during the same heatwave in Australia in 2019, there was a spike in pup abandonment in the grey-headed flying fox (Pteropus poliocephalus), where at least 2612 pups died resulting in reduced recruitment for the subsequent generation (Mo et al 2021).…”