Pills give degree of pest control

A smarter way of cutting possum numbers, by using contraceptive "pills", has moved closer to reality through research undertaken by University of Otago PhD graduand Alexandra Kafka.

German-born Miss Kafka (36) said it was "very exciting" to have completed her PhD in pharmacy and to be graduating.

• University of Otago graduands 

She is among about 260 graduands in education, teaching and pharmacy who will graduate from the university in person at the Dunedin Town Hall at 3pm today.

Miss Kafka, who recently took up a senior job in a pharmaceutical company in Munich, Germany, said it was "great to be back at least for some time in Otago".

"I feel very privileged to have been given the chance of doing a PhD here at Otago," she said.

Her research, which began in 2006, was backed by an Otago University postgraduate scholarship.

Bushtailed possums were a "major pest" in New Zealand, heavily damaging native trees and vegetation, sometimes out-competing native animals for food and also eating the eggs and chicks of some native birds.

Possums eat an estimated 9000 tonnes of leaves, berries and fruit throughout the country every night, Forest and Bird says.

Miss Kafka said poisoning and other control methods had cut possum numbers from about 70 million in the 1990s to an estimated 30 million.

Through the use of 1080 poison, it was possible to kill more than 90% of possums in a local area within two days, but possums from unaffected areas quickly moved in and replaced those that had died.

"It's just a temporary solution; it's not long term," Miss Kafka said.

More development work would have to be done before the particular contraception approach she had studied could be widely used.

"It's looking very promising, but we're not there yet. I've provided a good platform [for further work]."