Feral deer eradication protects threatened turtles
Issued: 21 Nov 2024

The eradication of pest species is part of continued efforts to ensure Wild Duck Island remains a conservation haven for vulnerable flatback turtles.

Photo credit: © Queensland Government

Issued

21 November 2024

Region

Capricorn

One of the 90 islands of Broad Sound Islands National Park, Wild Duck Island is a truly special place with many cultural and natural values—including hosting the largest rookery of flatback turtles (Natator depressus), a vulnerable species only found in Australia.

Up until recently, the island was also the graveyard of a partially constructed resort, abandoned in the early 1980s and left to decay.

In 2018, a turtle monitoring program, that was revived after a 10-year break, discovered that the island rookery supported far more nesting flatback turtles than anywhere else in the Great Barrier Reef. This prompted the Queensland Government to acquire the resort lease and embark on a successful restoration project to remove the abandoned resort materials from the island.

Deer are not meant to be here

Feral rusa deer (Cervus timorensis) are believed to have been illegally introduced to Wild Duck Island in 2005. Knowing the detrimental environmental impacts that ungulates (hooved mammals) can have on natural environments, our Rangers began their effort to control this pest species in 2007.

Rangers embarked on a long-running program involving ground and aerial control methods. Due to funding restraints, logistics and the evasive nature of the deer, the program initially focused on impact reduction and population control, rather than eradication.

Photo of herd of deer in black and white, using remote camera.

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Feral rusa deer were causing significant impacts to the island’s natural values.

Photo credit: © Queensland Government

Feral deer versus flatback turtles

In 2017, Rangers found that feral rusa deer were trampling the beach in high numbers and they were concerned flatback turtle egg clutches were being crushed.

Turtle researchers working at night observed the deer were often seen to be scaring female turtles attempting to leave the water, stopping them from emerging to nest on the beach.

The deer’s growing population was also causing significant impacts to the island’s natural values, by feeding on and depleting native vegetation, damaging wetland ecosystems and spreading pest plant species.

Photos of deer and turtles on a beach using remote camera.

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Remote cameras showing feral deer trampling over flatback turtle nests.

Photo credit: © Queensland Government

Ramping up rusa deer control

In 2018, funding was granted and the feral deer control program moved from impact reduction to an eradication project. By 2021, most of the deer had been removed, however around 10–20 of the more elusive animals were evading the detection methods being used at the time.

A collaborative control program—involving us (Queensland Parks and Wildlife Service), through the Reef Joint Field Management Program (a partnership with the Great Barrier Reef Marine Park Authority) and the Department of Primary Industries (DPI), through Biosecurity Queensland—began in 2019.

In 2022, we incorporated advanced thermal detection and assisted aerial shooting technology into the program, allowing for enhanced detection in some of the thicker and heavier vegetated areas of the island. By 2023, 272 feral deer had been successfully removed from the island.

Eradication of feral deer

The island has now been officially declared feral deer free, after 44 remote cameras installed by DPI in February this year did not capture any deer images.

This is the first documented case of the eradication of feral rusa deer from an island in Australia.

Importantly, Rangers have observed the recovery of vegetation and enhanced nesting conditions for flatback turtles on Wild Duck Island since the eradication of the deer.

Pest Management Senior Ranger Steve said the eradication program has created promising possibilities for similar eradication projects on other Australian islands.

‘This eradication program had an immediate impact on the natural values on Wild Duck Island and shows how successful long-term planning and ongoing control methods can be. It also showcases the benefits that new technology can have on making programs more efficient and effective’ Senior Ranger Steve said.

‘Thanks to our collaborative partners at DPI, it’s a win for the island’s wetland ecosystems and sand dune habitat and is a great outcome for the conservation of the threatened flatback turtle.’

DPI’s Principal Science Technician Michael said introduced herbivore ungulates are notorious for overgrazing and trampling island vegetation.

‘They can cause enormous damage to vegetation communities and it’s a real positive to remove feral rusa deer from Wild Duck Island,’ Michael said.

Eradication of an invasive animal can be very difficult, but this program showed it can be successful on Queensland’s islands.

Now that feral rusa deer have been eradicated from the island, Australia’s largest flackback turtle rookery is protected and Wild Duck Island is even better conserved for the future and the native species that call it home.