Forest and Bird is calling for a ban on pet ferrets, after five ferrets were taken to Great Barrier Island recently.

Great Barrier Island is free of ferrets, making it a relatively safe haven for some of New Zealand's threatened native species including brown teal, kaka and fernbirds. The introduction of ferrets to the island would be a conservation disaster.

Forest and Bird's Biosecurity Awareness Officer, Karli Thomas, says that the people who took their pet ferrets to Great Barrier Island should be prosecuted. The Department of Conservation must put in place a complete ban on pet ferrets to remove this threat to our precious offshore islands.

"This incident shows exactly why ferrets must not be kept as pets," Ms Thomas says.

Ferrets are a vicious predator of many of our native birds, particularly ground-nesting birds such as brown teal, penguins and kiwi. Unlike their smaller relatives, stoats, ferrets are capable of killing an adult kiwi. Ferrets also engage in 'spree killing', where they slaughter more prey than they can eat at one time.

"If even one desexed pet ferret got loose on a conservation island it could be a 'ferret in the chicken coup' scenario - but it would not be chickens, it would be our endangered native birds," Ms Thomas says.

The Department of Conservation has already undertaken public consultation on what to do about pet ferrets, and the public response was a resounding call for a complete ban - 77% of respondents supported this option.