Giant lizards could help prevent sheep from being eaten alive in Australia, say University of Cambridge researchers

The emergency of blowflies - which lay eggs on the backsides of sheep that hatch into flesh-eating maggots - could be controlled in Australia with the help of giant lizards called heath goannas.

A study by the University of Cambridge has found that these giant scavenging lizards could save Australian sheep farmers millions of dollars a year.

They lose an estimated £280million a year to the problem, known as ‘fly strike’.

Heath goannas act as natural clean-up crews by clearing maggot-ridden animal carcasses from the landscape.

The study was carried out at 18 sites across the Marna Banggara Rewilding Project area on Australia’s southern Yorke Peninsula, where more than 90 per cent of the native mammals are now extinct.native large reptiles like heath goannas is vital in restoring Australia’s ecosystem and the services it supports.

Boosting populations of native large reptiles like heath goannas will be vital to restore Australia’s ecosystem and the services it supports, the study suggests.

“We found that Australia’s native scavengers like heath goannas are much more effective in removing blowflies from the landscape than invasive scavengers like European foxes and cats,” said Tom Jameson, a PhD researcher at Cambridge’s Department of Zoology and first author of the report.

“Blowflies are a massive problem for the Australian sheep farming industry. They cause a horrible disease that is expensive for farmers to manage and a real animal welfare problem for sheep,”

Sheep suffer painful wounds when blowfly maggots burrow into their flesh and begin to eat them alive. The disease affects the market value of sheep, reduces their breeding success and often results in their death.

The study - in the journal Ecology and Evolution - is the first to show the importance of large reptiles as scavengers and compared the scavenging activity of different animals.

Tom left hundreds of dead rats at feeding stations, with camera traps, across the landscape and returned after five days to see whether the rats had been eaten, and to count the number of blowfly maggots left on any remaining carcasses.

Camera trap footage showed native Australian scavengers ate more of the dead rats, and with them the flesh-eating maggots, than scavengers introduced from Europe.

“It was disgusting – we were counting maggots,” admitted Tom. “After five days we’d find over 1,000 maggots in one rat if a scavenger hadn’t found it. Those maggots produce blowflies that can spread up to 20 kilometres in a week, putting local sheep flocks at risk of fly strike.”.

In a natural situation, any dead animal in the landscape will fill with blowfly maggots very quickly.

“The results suggest that conservation work in southern Australia to remove invasive species should also focus on boosting the population of heath goannas and other native species because they’re really important for the wider ecosystem,” said Tom. “As well as benefiting native wildlife this will have knock-on benefits for the local agricultural industry, and also attract more wildlife tourism.”

The heath goanna is an endangered species of giant lizard native to the heathlands of southern Australia. It can grow up to a metre and a half in length and feeds on the carcasses of other animals, as well as catching live animals.

Reptiles like the heath goanna are the largest remaining native land scavengers in much of Australia today.

Marna Banggara, supported by Narungga traditional owners, is an ambitious rewilding scheme that aims to restore ecosystem health by reintroducing missing native Australian species. Eighteenth-century European settlers to Australia brought with them red foxes for hunting, and cats as pets, which has decimated Australia’s native wildlife, including many scavengers..

The research was funded by the Natural Environment Research Council (NERC) and Chester Zoo.