Flying-fox mass dying events and heat stress events

Flying-foxes can be particularly susceptible to mass dying events commonly caused by heat stress, but can also be caused by natural disasters such as fire, cyclone and food shortages caused by droughts.

Heat stress events in flying-foxes can occur when where the temperature exceeds and stays above 38°C, and particularly when temperatures exceed 42°C or when there is a combination of high heat and high humidity. These conditions are most likely to occur in Queensland in the warmer months of November to February.

Heat stress occurs when flying-foxes can no longer regulate their body temperature, often collapsing out of trees from hyperthermia (Welbergen et. al., 2008).

A flying-fox heat stress forecaster website is available via Western Sydney University. This site combines temperature forecast data with known locations of flying-fox roosts to identify areas with potential risks for heat stress in the following 72 hours.

Managing and responding to flying-fox heat stress can be complex and requires consideration of a number of risk factors to both flying-fox and human health.

The Department of Environment and Science has been working with experts in flying-fox biology and flying-fox care to develop an interim guideline for those responding to, or managing potential flying-fox heat stress events.

This guideline may be useful for land managers, wildlife rescuers volunteers, veterinarians and the general public in preparing for heat stress events, or to provide technical guidance during a heat stress event. It is important to remember that handling bats carries specific risks for human health, and people should never touch flying-foxes without immunisations and appropriate protective equipment.

The interim guideline is currently being reviewed and updated following feedback from users, and will be published as a final guideline later in 2021.