Establishing an 'Overhead Irrigation System' to Cool Flying-Foxes During Heatwaves - Equipment & Modular Design

Establishing an 'Overhead Irrigation System' to Cool Flying-Foxes During Heatwaves

Increasing numbers of heatwaves are predicted for the future due to the onset of climate change. As several of Australia's flying-fox species are vulnerable or endangered, it is imperative to consider long-term strategies to conserve these animals in the face of more frequent Heat Stress Events. 

This increase has placed a huge burden on the local rehabilitation wildlife groups who are left to manage the potential huge mortality and morbidity of flying-foxes affected by extreme heat in each colony. Therefore it is extremely important to develop effective means of remotely monitoring and managing flying-fox colonies during extreme weather so that unacceptable death rates of vulnerable flying-foxes do not occur (Dr Kerryn Parry-Jones, 'Remote Management of Heat Stress Events', 2020).

Approval from the Land Manager (ie. local Council, State Parks, or  Property Owner) is essential before sprinkler trials can be set up in a flying-fox colony. Once approval has been obtained and a heatwave management plan is in order, an arborist can put the sprinklers up within the canopy and above the canopy, so that the spray comes down like light rain.

If enough trees within a colony are equipped with sprinklers then it should be possible to alter the temperature of the site over the period of time that is the most dangerous for the colony. At Singleton colony, the sprinklers were managed remotely via a phone app. According to Dr Kerryn Parry-Jones, 'smart sensors' could be programmed to not only monitor the site but respond automatically by turning on the sprinklers when specific conditions are reached.

At Yarra Bend Park Flying-fox colony, Melbourne, Lawrence Pope reported that half the sprayers are 3 metres high and spray a diameter of 7 metres and are battery powered. The other half are petrol pump powered and rise above the canopy at 6 metres. All the sprinklers rotate slowly so that the roosting flying-foxes get a light cool spray every couple of minutes.

On days that the Bureau of Meteorology (BOM) predicts that a heatwave is likely in Melbourne, the sprinklers powered by the fuel generators are run from 10 am in the morning, so that the bats get the advantage of the cooling water, and are fully hydrated, enabling them to withstand the heatwave conditions. In fact, since the installation of the sprinkler/misting system, no further mass flying-fox deaths, due to heat stress, have occurred in the areas where the sprinklers operate (Lawrence Pope, President Friends of Bats & Bushcare Inc., February 2020)


(John Chambers, Engineer, 2 May 2020, Email:

i. The Spray System has been laid out as a typical irrigation system where hydraulic balance, economy and an even coverage/precipitation rate over the sprayed area is achieved. Approximately sprayed area is 2800 sqm.

ii. The whole system is portable and easily installed and dismantled by two people.

iii. The box trailer mounted diesel pump unit would also transport all the spray system materials to site.

iv. The Sprinkler Layout

The 10 Nelson R33 Brown sprays are rotating brass sprinklers. These are laid out in a triangular pattern for even precipitation. The spray radius is 14 metres.

v. Each R33 spray head will be mounted on a 6 metre vertical riser, stabilised by fixing to a fence star picket driven into the ground. The spray riser pipe can be of any length, depending on vegetation height.

vi. All on the ground pipe laterals will have screwed connections between the vertical riser pipe and the main pipeline for easy installation and dismantling.

vii. The mainline between the pump unit and the pipe lateral can be of a variable length, depending on the distance between the water source and the area to be sprayed.

viii. The Pump Unit is a diesel engine self priming fire pump unit similar to 'Yanmar Fire Captain' which retails at approximately $3,330.00.

ix. The pump unit would be fixed centrally to the floor of a standard box trailer, all pipes and fittings would be transported to the site and stored on this trailer.

x. It is thought that a large flying-fox colony would require 3 of the modular spray systems outlined in this document.



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