Ferrets in the fast lane

Introduced predators could turn the MacKays to Peka Peka Expressway into a highway to hell for native species north of Wellington.

Conservationists fear the fourlane expressway, which opened in 2017, has become a ‘‘predator corridor’’ as an increasing number of ferrets are trapped near the road.

Pest trapper Shane Cave said it was believed ferrets were travelling down the planted road margins.

While other mustelids such as weasels and stoats were found in the area, ferrets were an unwelcome addition, and a further threat to native species.

Ferrets previously had very little presence south of the area between Waikanae and O¯ taki, he said.

Matu Booth, manager of Nga¯ Manu Nature Reserve, which borders the expressway, said they caught 14 ferrets between December 2017 and February last year, and expected to record a similar number this year.

‘‘Anyone would regard that as a high number.’’

While ferrets and other pests were undoubtedly using the road and its margins to travel south, he was not certain the expressway was completely to blame for the large numbers of ferrets being caught.

Rabbits were their main food source and a recent spike in their population was thought to have

resulted in a boost in ferret numbers.

Cave said he and other pest trappers and conservationists were disappointed to see no predator trapping along the road.

Greater Wellington Regional Council had told him it only required the New Zealand Transport Agency to control pest animals in so far as to maintain plantings along the expressway.

A GWRC spokesman directed Stuff to correspondence between Cave and his associates and the council, which said the council was satisfied that NZTA had complied with its obligations.

NZTA project delivery senior manager Chris Hunt said the agency had upheld the requirements for a maintenance regime focused on pests that posed a risk to planting.