Owls survive rodent wipe out

http://www.sciencealert.com.au/news/20082802-16966.html

Owls survive rodent wipe out
Thursday, 28 February 2008
University of Auckland

Morepork are thriving in predator eradication areas, despite worries ongoing poison methods may also put the small owl at risk.

Research by University of Auckland student Elisabeth Fraser, and published in the New Zealand Journal of Zoology, suggests morepork numbers are higher in areas where poison eradication projects have been established than outside the control areas. Previously, there had been fears the owl would be at risk of secondary poisoning, through feeding on rodents and insects that had eaten the poison. However, such prior published research on secondary poisoning of morepork was conducted at island sites where poison was pulsed once or few times to eradicate rats or mice without ongoing application of the poison.

Morepork are the only native species of owl in New Zealand and live in forest areas across the North and South Islands. Elisabeth’s research collected data on the number and frequency of morepork calls, an indication of the number of birds in the area, at sites across the Waitakere ranges, including sites of the PUBLIC conservation project Ark in the Park. Over twice as many calls were heard inside the Ark in the Park area, where rodents are controlled with poison, than at unmanaged sites.

"Poison is a common method used for managing rodents as a means of protecting native species and ecosystems," says Miss Fraser. "However, native animals, like the morepork, feed on rodents and other animals, which feed on the poison grains. There has been some worry that these native animals may be at risk of secondary poisoning through the foodchain 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."

Editor's Note: Original news release can be found here.

ENDS

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