Scent chemicals of the Brushtail possum, Trichosurus vulpecula

The common brushtail possum (Trichosurus vulpecula) is the most widespread browsing marsupial in Australia, where it occupies woodland, agricultural, and urban environments. Following its introduction into New Zealand in the 19th century it has become a major feral pest, threatening native forests. The adaptability of the possum is thought to be due in part to its social organization, in which chemical communication is important. Possums have cloacal glands and exhibit related marking behavior. This study sought to characterize the chemicals involved in scent marking. Swabs were taken of the cloacal region of 15 possums (5 females, 10 males) from north-eastern Tasmania and analyzed by gas chromatography–mass spectrometry. There was a large number of compounds present, including 81 branched and unbranched, and saturated and unsaturated, fatty acids (C₄–C₁₅) and alcohols (C₆–C₂₆); 27 esters of 2,6- and 2,7-dimethyloctanol; 29 esters of formic acid; 39 sulfur compounds including S8 and a series of dialkyl disulfides, trisulfides, and tetrasulfides (C₄–C₁₀); and several alkylglycerol ethers. Many of these cloacal compounds are new to biology. There was considerable individual variability in the relative amounts of compounds found, and no evident sex differences, although the study was not designed to test this. This pattern suggests that these compounds may be acting collectively as a signature mixture of semiochemicals, carrying information on the individual, its kinship, and physiological and social status. This is the first detailed description of putative semiochemicals in any marsupial species.