U.S. Fish and Wildlife Service eradicates yellow crazy ants from seabird wildlife refuge

The yellow crazy ant species that threatened vital seabird colonies at the Johnston Atoll National Wildlife Refuge has been eradicated.

The successful removal of the invasive species from the 70-mile infestation area by the U.S. Fish and Wildlife Service is the first in which yellow crazy ants have been removed from such a large area.

“Thanks to the brilliant work of these volunteers and staff, as well as the help of our partners, this is the first time an invasive ant species has been eradicated on such a large land area in the U.S.,” Kate Toniolo, superintendent for the Pacific Remote Islands Marine National Monument, of which the refuge is part of, said in a release Monday.

The refuge is one of the “most isolated atoll formations in the world.” It is home to tens of thousands of seabirds, including the world’s largest colony of red-tailed tropicbirds. The habitat, which sustains 15 species of breeding seabirds, is also the only seabird habitat in over 570,000 square miles of open ocean.

In 2010, USFWS biologists discovered invasive yellow crazy ants on Johnston Island. The ants threatened the seabirds significantly, and increased in such density that they swarmed anything on the ground, spraying formic acid on seabird chicks and adults, resulting in blindness, injury and death. The ants prevented red-tailed tropicbird nesting in the infestation area, putting the island’s entire seabird colony at risk.

Almost 100 staff members and volunteers worked in specialized invasive species control teams, known as Crazy Ant Strike Teams, to eradicate the ants, contributing over 130,000 field hours.

The teams experimented to bait and eradicate the ants. After the bait treatments on the island, crews hand-searched the island multiple times to remove any remaining ants. Two conservation detection dogs were also brought to the refuge last December to sniff out any last ants, finding none in the 118 total miles the dogs surveyed. The last known sighting of yellow crazy ants at the refuge was in December 2017, according to a release from USFWS on Monday.

This eradication success could become a “roadmap” for cases of invasive yellow crazy ants in other protected areas, USFWS said.

“While the mission of the Crazy Ant Strike Team is complete, the Service will continue to focus on habit restoration, preventing the spread of other invasive species and the conservation of the wildlife and habitat protected by Johnston Atoll National Wildlife Refuge,” Stefan Kropidlowski, deputy superintendent for the Pacific Remote Islands Marine National Monument, said in the release. “For now, we celebrate that the refuge is once again a safe haven for the amazing seabirds that call this incredible place home.”