Officials at the Animal Health Board - one of the biggest users of the pest poison 1080 - say a new study shows aerial drops of the poison increases the breeding success of some native wildlife.
Scientifically-known as sodium fluoroacetate, 1080 is used to control animal pests such as possums spreading a livestock disease, bovine tuberculosis.
The poison was dropped as part of a continuing study by the University of Otago on geographically isolated South Island robins in the Dunedin area.
It killed their main predators - rats and possums - at a controlled site, but all 19 robins survived.
At least one chick per nest was subsequently produced from 67% of the monitored nests.
The 16 robins at the uncontrolled site all survived too, but only 8% of monitored nests succeeded with at least one fledgling.