A published review found that our current understanding of the effectiveness of intervention methods for reducing flying-fox mortalities during extreme heat events is mainly anecdotal rather than based on scientific studies.
Read A review of intervention methods used to reduce flying-fox mortalities in heat stress events
There is research underway to guide best practice for helping flying-foxes during extreme heat events. Therefore, the guidance provided here is likely to change with new findings.
It is important to note that human presence in a camp at such times can increase the stress and activity levels of the flying-foxes and potentially lead to greater harm.
Forecasting extreme heat events
To help licensed wildlife rehabilitators and land managers prepare for and respond effectively to flying-fox camps affected by extreme heat events, a Flying-Fox Heat Stress Forecaster has been developed by a team from Western Sydney University and the University of Melbourne. The forecaster predicts the camps where flying-foxes are likely to experience extreme heat up to 72 hours ahead.
The forecaster is being continually improved by ongoing research.
Read Forecasting wildlife die-offs from extreme heat events.
Vegetation restoration to buffer the severity of extreme heat events
During extreme heat events, flying-foxes typically descend to the trunks of trees seeking the coolest microclimates. If there is enough mid- and understory vegetation to provide shade, the severity of heat stress is likely to be reduced.
Retaining and restoring mid- and understory vegetation in flying-fox camps is a viable way of improving site conditions for flying-foxes during an extreme heat event.
Approvals required for intervening at a flying-fox camp during an extreme heat event
You need to be licensed to rehabilitate wildlife. If you want to get involved, first step is to join your local wildlife rehabilitation provider, which holds a Biodiversity Conservation Licence un the Biodiversity Conservation Act 2016. The licence must specifically authorise the person as being able to rescue and rehabilitate flying-foxes.
If you are not sure about your coverage under a current licence, contact your local wildlife rehabilitation organisation or, for individual licences, the Wildlife Team at the Department of Climate Change, Energy, the Environment and Water by email at [email protected].
Read Rehabilitating native animals
Alternatively, you have a job which lawfully entitles you to intervene in animal welfare issues (for example with the council, the Department of Climate Change, Energy, the Environment and Water, including the National Parks and Wildlife Service, or the RSPCA) or you are a registered veterinarian.
Standards and guidelines
The Code of practice for injured sick and orphaned flying-foxes establishes the minimum requirements for the rescue, rehabilitation and release of animals in care. It also specifies training and reporting requirements and measures to reduce the risks to the health and safety of personnel. Compliance with the standards in our codes is a condition of the Biodiversity Conservation Licence issued to wildlife rehabilitation providers. There are a range of resources available to assist wildlife rehabilitators meet the requirements for standards of care including 12 short videos that demonstrate practical techniques for flying-fox rehabilitation.
Read wildlife rehabilitation standards of care
If organisations intend to take action in extreme heat stress events, the department encourages planning to ensure that the organisation has the resources necessary to meet the standards.
Arranging access to flying-fox camps
Access to sites where animals are affected needs to be negotiated with the relevant landholder.
For national parks, contact the State Duty Officer on 02 9895 6444.
For Crown Lands, contact customer service during business hours on 1300 886 235.
For state forests, contact the Forestry Corporation of NSW.
For council-managed land, check the relevant local council website for contact details.
What to do during an extreme heat event
During an extreme heat event, flying-foxes usually occupy the coolest microhabitats available to them. Disturbance may move them away from these preferred areas.
Take great care to avoid unnecessarily disturbing flying-foxes at this time.
It may not always be possible or appropriate to intervene if approaching heat-stressed flying-foxes would cause disturbance to other flying-foxes in the vicinity. Intervention is not mandatory and will depend on the circumstances.
Generally, interventions are only required if there are flying-foxes that have descended to the lowest sections of tree trunks seeking refuge.
We recommend that wildlife rehabilitation organisations and land managers develop an incident response protocol relevant to the local area that can be used by their members when flying-fox camps suffer heat stress.
General health and safety issues must be identified beforehand, and appropriate measures implemented during the event.
Hand-spraying water onto heat-stressed flying-foxes
There is scientific evidence that hand-spraying water onto flying-foxes when they are near or on the ground can provide cooling. .
This should only be done if flying-foxes don’t try to move away from you. If they show any signs they are being disturbed by your approach, continuing to approach them can cause them to try to move away, increase their body temperature and increase their stress.
Highly heat-stressed flying-foxes that don't respond to spraying should be observed for 15 minutes before spraying again. After a period of observation, they may then be removed from the camp by an experienced flying-fox rehabilitator for any necessary treatment.
Removing flying-foxes from a camp for treatment
Flying-foxes that are severely affected by an extreme heat event may need intensive cooling and/or rehydration. In some cases, after an assessment by an experienced flying-fox rehabilitator, the animal may need to be removed from the camp.
Flying-foxes must be handled only by vaccinated individuals that are following the Australian Department of Health guidelines for vaccination and boosters and wearing a mask, protective clothing and puncture resistant gloves.
Read Immunisation health book: vaccines rabies and other lyssaviruses
If injured flying-foxes are moved during an extreme heat event for rehabilitation, they should be released in accordance with the Code of practice for injured sick and orphaned flying-foxes.
Using sprinklers for site cooling
The use of sprinklers during an extreme heat event has the potential for making the camp more tolerable for flying-foxes. However, there are concerns that spraying water under certain conditions may increase humidity. Since flying-foxes shed heat through evaporative cooling, increases in humidity may render their natural cooling mechanisms ineffective, exacerbating heat stress.
There are also concerns that the operation of sprinklers may cause flying-foxes to take flight during critical times of an extreme heat event, which would also exacerbate heat stress.
To address these concerns, the Department of Climate Change, Energy, the Environment and Water has commissioned a research trial of sprinklers at a flying-fox camp in south-west Sydney. This research trial commenced in 2020 and is continuing.
Since the commencement of the research trial, there has only been one day of extreme heat at the trial site. Interim findings from this event indicate that sprinklers show promise at buffering local microclimatic conditions from reaching lethal conditions, however the effects are very localised to the area immediately around the sprinklers.
Conclusive findings will require further data collection over more extreme heat events. This is expected to help inform best practice for using sprinklers as a mitigation strategy.
Collecting data about mortality and effectiveness of interventions
Recording information during and after an extreme heat event can provide a better understanding of the nature and severity of extreme heat events on flying-foxes, and contribute to more effective management responses.
Information should include the date of the event, the location of the camp, and whether any flying-foxes died. If available, information on the number and species of flying-foxes present in the camp, and the mortality by age class and species is very useful. Information about interventions and how many flying-foxes were taken into care is also very useful.
Monitoring the site in the days following the extreme heat event is important because flying-foxes can show the impacts of heat stress for several days after the event.
All flying-foxes must be handled only by vaccinated individuals that are following the Australian Department of Health guidelines for vaccination and boosters and wearing a mask, protective clothing and puncture resistant gloves. This includes directly handling dead flying-foxes.Western Sydney University researchers have created an Online Flying-fox Heat Stress Data Form to help centralise information that is collected.
Any banded dead flying-foxes must be reported to the Australian Bird and Bat Banding Scheme.