The Welfare of Evicted Possums

During 2009 & 2010 we assisted a university student, Natalie Waller from UQ Gatton, School of Animal Studies with her Honours Project ? ?Does evicting common brushtail possums (Trichosurus vulpecula) from roofs compromise the welfare of the animals?

This study used a manipulative experiment to determine if the eviction of female common brushtail possums from roofs compromises their welfare by determining if evicted animals:

1. relocate to an alternative den site outside the pre-eviction home range;
2. lose body weights after eviction; and
3. shift their home range after eviction.

      

Natalie used radio collars to track the possums for two weeks before and two weeks after they were evicted to determine their home range use. This study was of great interest to us as the eviction of brushtail possums makes up a large portion of our business and the welfare of the animals is important.

The thesis is now complete and we were pleasantly surprised by the findings.

? Female brushtail possums in suburban Brisbane have very small home ranges often only 4-8 house blocks (averaging 0.7 hectares). The size of the home range appeared to be determined by the amount of vegetation. One possum in a commercial area where the trees were sparsely distributed had a much larger home range than possums in highly vegetated areas.

? When evicted from the house they stayed in the same street usually only 2 or 3 houses away and at most moved 70 meters from the original den site.

? Two possums lost body weight which could be associated with stress or have been affected by having large back rider joeys. There was not significant change, however, in body weights between evicted and control (animals not evicted) animals, many of the evicted animals actually gained weight.


        

? The main welfare issue that was raised was injuries sustained from capture in cage traps. We have begun transferring our cages over to a smaller mesh which reduces this problem.

? The average number of possums captured per roof was 1.3, 44% male, 56% female.

? A few of the houses had nest boxes installed and the animals evicted from these roofs preferred to go into other den sites and not use the nest boxes provided.

? The possums moved small distances, most of which moved to other roofs, a few animals moved to garages and one to a palm tree which was beside the original roof the possum was evicted from.

This study has shown that eviction does not currently cause compromised welfare to female brushtail possums evicted from roofs in Brisbane.

We would like to thank Natalie for including us in this study and for the many beautiful photos she has allowed us to use on our website, including the below photos of two differnent rare male white coloured Brushtail possums occasionally found in Brisbane.

      


            

                Another uncommom Brisbane Brushtail Possum with a white tipped tail.