Controversial poisoning programmes to control predators are having a remarkable effect on New Zealand's native owl, the morepork, an Auckland University researcher has discovered.
Concerns the poisoned predators, including rats and mice, would be eaten by morepork, poisoning the owls in the process, appeared to be unfounded, says researcher and ecology student Elisabeth Fraser, 22.
The owls appeared to be twice as numerous in areas where predator eradication methods using poisons were present, she said.
Miss Fraser collated data on morepork calls between December 2006 and January 2007. She spent 45 minutes at 16 different sites - half of which were under poison control - in Auckland's Waitakere Ranges.
More than twice as many calls were recorded in the poisoned areas, she said.
"There has been some worry that these native animals may be at risk of secondary poisoning through the food chain.
"But, at least in the case of the morepork of the Waitakere Ranges, this doesn't seem to be the case. In fact, the birds are thriving in these areas, probably due to the eradication of the rats and mice which feed on bird eggs and compete with the owls for food resources," Miss Fraser said.
Morepork live in forest areas across the North and South Islands, and can be easily heard at night, and often seen at day, quietly sitting on high branches.
The study is published in the latest edition of the New Zealand Journal of Zoology.