An invasion of foreign ants is threatening the lives of kiwi at one of New Zealand's premier coastal forest reserves beside the Whangarei Harbour.
The Department of Conservation (DoC) is undertaking a poisoning programme to try to eradicate the argentine ant (Linepithema humile) from the area around the Bream Head Scenic
Reserve.
In a four-day programme lasting until tomorrow, DoC workers are laying insecticide on a 16ha area at the reserve to kill the aggressive ant species before it threatens kiwi habitats there.
The active ingredient in the bait is Fipronil, the same substance used in flea collars.
It has proved successful in battling argentine ants on Tiritiri Matangi, an island in the Hauraki Gulf.
DoC technical support officer Andrea Booth said argentine ants were a major environmental and household pest.
"They eat invertebrates and nectar and are therefore in direct competition with kiwi, other native birds, and lizards."
The ants have also been known to swamp nests and kill chicks.
Although the honey-brown ants are not poisonous, they do bite people.
The infestation at Bream Head is of particular concern because of the high ecological value of the area, Ms Booth said.
Currently about 25 kiwi live in the reserve, and there are plans to restore the area to recovery level and introduce more native species, such as the North Island robin and the kokako.
DoC biodiversity threats ranger Jaap Knegtmans said the infestation started in houses in the area and was moving up paddocks towards the bush.
"At the moment we're lucky they are not in the main bush block yet," he said.
"Once these argentine ants get established they could jeopardise the whole recovery project."
Ms Booth said DoC hoped to eradicate the ants in three years, but the long-term success of the project would depend on the local community.
"The ants can't fly so they can only move great distances by people moving them - through bark or soil or plants."
Herald feature: Environment
