Possums in NZ prefer leaves high in available protein

13 May 2016

By identifying the forests, or tree species, that have high digestible protein concentrations, strategies can be put in place to protect those forests.

Researchers at The Australian National University (ANU) have found possums in New Zealand prefer to eat leaves high in available protein, giving authorities new evidence to help them limit possum damage to New Zealand's forests.

Possums are considered a pest in New Zealand, where the government spends  tens of millions of dollars each year to eradicate them. Possums are protected as a native species in Australia.

The new study by Dr Hannah Windley from the ANU Research School of Biology  compares the nutritional quality of New Zealand foliage with the damage possums do to trees by over-eating.

"We can use this new information to predict the impact possums have on forests in New Zealand, and it may also help in targeting control programs for managing this pest," Dr Windley said.

"By identifying the forests, or tree species, that have high digestible protein concentrations, strategies can be put in place to protect those forests."

Dr Windley analysed the nutritional value of leaf samples taken from 275 trees at four different times of the year.

"It is surprising that any relationship between nutrition and the feeding decisions of possums could be detected at all," Dr Windley said.

"There are many reasons why herbivores may eat from some trees and not others, and the fact that we could predict these feeding choices at a large-scale using a single nutritional measure highlights the important role that available protein plays in regulating possum populations in New Zealand."

The study, conducted with Landcare Research New Zealand and funded by the New Zealand Government, will help the country to improve strategies for managing possum populations.

The research is published in the latest PLOS ONE journal.