A study was made of the use of trees with hollows by 10 adult male and 6 adult female mountain brushtail possums (Trichosurus caninus) at a 35-ha site in central Victoria, south-eastern Australia. Radio-tracking was used to identify which trees were being used as den sites by animals during an 18-month period between September 1990 and March 1992. Analyses of the data showed that, although 113 different trees were used by the 16 animals, most were occupied infrequently. The total number of trees used by a given animal ranged from 5 to 23. However, the majority of individuals spent most of their time denning in 1-3 trees. Of the 113 den trees, 70 were found to have been used by only 1 animal, 54 trees were used exclusively by males, and 28 trees by females only. Twelve trees were used extensively (on >40 occasions) but only 1 was used extensively by both sexes. Most of the T. caninus radio-tracked typically used 2 or more nest trees per week, indicating that animals moved frequently between den sites. Some animals used up to 6 different trees per week. Some possible reasons for this behaviour in T. caninus are discussed.

The results of a radio-tracking study of the uses of den trees by Leadbeater's possum (Gymnobelideus leadbeateri McCoy) at Cambarville in the mountain ash (Eucalyptus regnans) forests of the Central Highlands of Victoria, south-eastern Australia, are described. Animals were radio-tracked for three periods of 5-20 days in July 1990, November 1990 and July 1991. A total of 14 individuals was tracked and they occupied 11 different trees with hollows on the 10-ha study site. Preliminary findings showed that some animals moved between hollows in different trees, and most animals used two or more trees. The distances between utilised trees usually exceeded 50 m. Possible reasons for the den-swapping behaviour include attempts to either or both relieve burdens of ecto-parasites and to reduce the risk of predation. There were several examples, in each of the three radio-tracking periods, of two or more radio-collared adult breeding female animals simultaneously co-occupying the same nest tree. This result was different from some of the general findings of an earlier study of G. leadbeateri at Cambarville.

This paper describes a new type of bracket to support 'Elliott' Type A traps for trapping small arboreal and scansorial marsupials in trees. The trap bracket is cheap, robust, and safe, quick and easy to install.