Aboriginal rangers thwart crazy ants

By Amanda James 25 November 2010
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Aboriginal rangers in Arnhem Land have won a national award for their work to contain the invasive yellow crazy ant.

ABORIGINAL RANGERS HAVE WON a national environmental award for their work helping to control one of the world’s worst invasive species.

This recognition comes after six years of battling the ecologically destructive yellow crazy ant (Anoplolepis gracilipes) on Gove Peninsula, about 700 km east of Darwin.

“Wherever this ant is in the environment, it out-competes or kills much of the invertebrate fauna” says Dr. Ben Hoffmann, a CSIRO ant ecologist, who works with the local Indigenous rangers in Nhulunbuy to manage the species.

It’s unknown where the crazy ants – so-called because of their erratic movement when stirred – originated from or even when they arrived in Australia. Theories range from them having hitched a ride on mining equipment in the early 1900’s, to them having found their way onto an air force base during WWII. 

Whatever their method of arrival, the ants have wreaked havoc on local environments by forming super-colonies that can displace ‘keystone’ species, altering ecosystems.

Local knowledge

The rangers’ knowledge of the land and ability to communicate with traditional owners, coupled with Ben’s expertise, has been a recipe for success in eradicating the ants from 21 sites, covering 246 ha of the peninsula.

“I think it’s my duty as a Yolngu Aboriginal man from this area to look after the land for future generations,” says Daryl Lacey, senior Dhimurru ranger working on the yellow crazy ant management project.

Competing against corporations including Fuji’s Xerox and the Coca Cola Foundation, the Dhimurru rangers distinguished themselves in the competition for the Origin Gold Bansksia Award by their grassroots efforts.

“[Dhimurru] do it beautifully in the sense that they bring together so many sectors – CSIRO, along with government funding, private-interest funding from the Rio Tinto mining group, and … working with other indigenous groups. They just ticked every box,” says Graz VanEgmond, executive director of the Banskia Environmental Foundation.

The rangers also worked with Conservation Volunteers of Australia, whose members helped them map the ant sites and form eradication plans.

When the project began in 2004, the team suspected there were only 20 infested locations within an area of 100 ha. This assessment soon changed. “When we first started, we were intent on total eradication, but as we went along we discovered there were many more sites than we anticipated, says executive director of Dhimurru Aboriginal Corporation, Steve Roeger. “So we’ve moved to a containment and management regime because we will never get the resources to eradicate them completely.”

Lessons learned

To find the ants, the rangers, using their local expertise, surveyed the landscape and mapped the ants’ distribution on foot; a helicopter then delivered a bait toxic to all species of ant. Local species were also wiped affected, but they returned within a year, says Ben.

The ant colonies are so widespread, however, that the Dhimurru group has initiated an awareness campaign with warning signs about the ant in the traditional Yolngu language and in English.

Lessons learned from the crazy ant management in Nhulunbuy will be applicable for containing the ants in other areas, such as on Christmas Island, where the ant has widely dispersed and devastated the ecosystem, says Ben.