Do brushtail possums (Trichosurus vulpecula) show preferences for exogenous odours associated with food?

The brushtail possum is the major vertebrate pest in New Zealand, and durin g control operations a variety of odours are used to lure possums to traps and poison baits. Paired tests were performed in large outdoor enclosures t o determine if the preferences of possums for these odours differed. In Exp eriment 1, we tested the preferences of six possums for orange, cinnamon, c loves, peanut and almond odours. The subjects showed no significant prefere nce for any of the odours, and no one was preferred more than water. In Exp eriment 2, we tested the preferences of the same six possums for the synthe tic odour of the plant Dactylanthus taylorii, which appears to be highly at tractive to wild possums in New Zealand. Preferences for the synthetic Dact ylanthus odour were determined relative to an odour the possums were famili ar with (orange) and a novel odour (peppermint). There were no significant differences between the responses shown by the possums to the three odours. Possums may have shown little preference for these odours because they wer e either unfamiliar (the distribution of Dactylanthus has become restricted in New Zealand) or were not associated with a food. These results suggest that a positive post-ingestive experience is important for the formation of odour preferences.