Behavioral-Response of Brushtail Possums, Trichosurus-Vulpecula, to Baits Used in Pest-Control

Abstract

The behavioural responses of captive possums (Trichosurus vulpecula) were observed during first encounters with non-toxic and toxic carrot and pellet baits used in pest control programmes. Possums confronted with new baits first used smell in a highly discriminating way, and then taste, which sometimes changed their initial response. Toxic carrot baits were rejected by 27.5% of possums, equally by smell and taste aversion, and toxic pellet baits by 34% of possums, mainly by taste aversion. Few (5-7%) rejected non-toxic baits. Such non-learned aversion mechanisms therefore have an important role in the feeding behaviour of possums. A range of flavours tested, using barley as a food base, showed that only orange-flavored barley was significantly preferred to non-flavoured barley; 19 flavours had no significant effect, and 19 others significantly reduced barley consumption. Orange and cinnamon, which was ranked fourth and repels some bird species, were tested as masks for 1080 baits. Both flavours effectively masked the aversive smell and taste of 1080. The levels of toxic flavoured bait rejection were low and did not differ from those of non-toxic (flavoured or non-flavoured) baits. Very few possums were observed vomiting, a behaviour in other species that may assist survival.