Four kea were caught in Department of Conservation traps aimed at monitoring possum populations early last year, killing two of the endangered birds.
The birds were caught in the modified leg-hold traps in the Cook River catchment in South Westland in February 2014.
Two kea were caught by the toe and released unharmed, while the other two had broken legs and subsequently died from their injuries.
The Department of Conservation said it had stopped using leg-hold traps in non-forest habitats as a result of the deaths, which have prompted research into new monitoring methods.
Kea are classified as nationally endangered and are in decline, with fewer than 5000 estimated to be left.