Quick Dips

Female Possums Go Further

Dispersal of possums is a major headache for those trying to contain the spread of bovine tuberculosis or to protect native forest. Young male possums have long been known to leave home as they mature -- a behaviour they share with other mammals. The newly discovered habits of the occasional female dispersers now suggests that they pose a threat out of proportion to their numbers.

While fewer females wander, they are more likely to make several dispersing moves, with halts of several days or weeks in between --  maybe long enough to pass on any infection they were carrying. Typical female dispersers moved about 6 km, compared to 4 km for males, and the three longest movements (41, 31 and 25 km) were all made by females.

The discoveries came about as part of a review of possum dispersal commissioned by the Animal Health Board. DSIR Land Resources scientist Murray Efford compiled a database of possum records and analysed 25 years of possum tagging for evidence of immigration and emigration.

The results suggest the need for a rethink of the current models of the spread of bovine Tb by possums. Efford says that the female "super-dispersers" may be a key to understanding why possums are such successful colonists.

Possum control practices will be a theme at the Possum Innovators promotion in Palmerston North at the beginning of November. The Animal Health Board, MAF, DOC and Federatated Farmers, as well as a number of local firms, are sponsoring innovative products using possums.

"It is hoped that a product will be found which will take off and turn the burgeoning possum population around," says Suraya Dewing of the Manawatu-Wanganui Regional Council. "[Possums] are threatening our forests and overseas export markets and, as every farmer, forester and conservationist knows, finding a solution -- any solution -- is vital."