August 15, 2019
Flying-Fox Heat Event Response Guidelines - Dr Tania Bishop
Flying-fox behaviour monitoring is critical during heat wave conditions. Behavioural progression from animals showing signs of heat stress through to heat stroke will always follow a predictable consistent progression. The behavioural progression includes wing fanning, clustering, clumping to panting/wrist licking which is a means of using evaporative cooling to lower core body temperatures. Pregnant and lactating females can start fanning at temperatures as low as 23 degrees centigrade due to the higher metabolic demands of their physiological state.
1. Wing fanning, classified as Category 2, is normal cooling behaviour in minor heat stress.
2. Clustering, where bats start to move further down the trees into the middle-storey vegetation, is classified as Category 3a. It is important to note that bats at this stage should never be disturbed, because disturbance is likely to risk bats becoming stressed and taking flight, causing serious heat stroke and possible death.
3. Clumping, classified as Category 3b, is where flying-foxes will roost on top of each other on the shaded side of trees, at the base of trees or on the ground. Response personnel should be in place and set up for a response. Flying-foxes may not tolerate spraying of water at this stage.
4. Panting/wrist licking, often occurs at the bottom of trees, classified as Category 4, is utilised as a means of evaporative cooling to lower core body temperatures. High humidity heat events will reduce the ability of bodily fluids to evaporate and cool the body. Whereas in low humidity heat events, this will be effective at cooling the body, however flying-foxes will dehydrate very quickly.
Rescuers need to approach bats quietly to monitor for any signs of distress. If the bats are tolerant of a quiet approach, an attempt at spraying with water from a backpack can be attempted. Gradually increase the intensity of spraying so that each bat gets saturated with water. If after several attempts at spraying, some bats have not climbed back into the mid-storey, they should be taken for triage.
Do not immediately remove orphans that are roosting in trees, as mothers will often come back for babies once the situation has settled. It will be apparent over the next 24-48 hours if juveniles are truly orphaned.
Read more on the effects of heat events on flying-foxes, in the following powerpoint presentation prepared by Dr Tania Bishop.
