Rusa deer were stopping female flatbacks from laying on the beach and trampling their nests.
In a major boost for populations of threatened flatback turtles, the eradication of feral rusa deer from Wild Duck Island has been pivotal in protecting one of Australia's largest flatback turtle rookeries.
This is the first recorded eradication of feral rusa deer in Australia.
It's believed rusa deer were unlawfully introduced to Wild Duck Island in 2005, and as the population grew, they impacted on the island's natural values, including feeding on vegetation and trampling on critical sand dune nesting sites for sea turtles.
Wild Duck Island is approximately 330 hectares in size and is in the Broad Sound Islands National Park off the central Queensland coast.
The Department of Environment, Science and Innovation embarked on a long-running control program involving ground and aerial control methods, which initially focused on impact reduction and population control rather than eradication.
In 2018, an ongoing turtle research program found that Wild Duck Island is the largest flatback turtle rookery site on Australia's east coast.
Researchers discovered the feral deer were trampling the flatback's clutches of eggs and could prevent female turtles from leaving the water to nest on the beach.
In 2022, a collaborative control program involving the Queensland Parks and Wildlife Service, The Great Barrier Reef Marine Park Authority through the Reef Joint Field Management Program (RJFMP) and Biosecurity Queensland (BQ) targeted the elusive animals.
The program incorporated a Thermal Animal Detection System with a Thermal Assisted Aerial Shooting system which successfully removed all deer from the island.
By 2023, 272 feral deer had been removed from the island. In February 2024, 44 remote cameras installed by the Department of Agriculture and Fisheries did not capture any images of feral deer.
The island has now been declared free of feral deer, and rangers have observed the recovery of vegetation and enhanced nesting conditions for flatback turtles.
Senior Ranger Steve Burke said the eradication program creates possibilities for similar eradication projects on other Australian islands.
"This collaborative 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," Mr Burke said.
"It's a great win for the Island's wetland ecosystems as well as the flatback turtle rookery and is a great outcome for the conservation of a threatened species.
"I'd like to thank DAF for their assistance with this eradication program."
DAF's Principal Science Technician Michael Brennan said introduced herbivores are notorious for overgrazing on island vegetation.
"They can cause enormous damage to vegetation communities, and it is a real positive to remove feral rusa deer from Wild Duck Island," Mr Brennan said.
"Eradication of an invasive animal can be very difficult but this program showed it can be successful on Queensland's islands."
