St Bees Island
July 2010
The field trips to St Bees Island are now running on an annual basis rather than three or four trips per year. This reflects the maturity of this long-term study site. We have been studying this population for over 12 years and will continue. It has taken some years to build the picture of what is happening among the koalas and in the plant communities that support them. At the moment we are focusing on publishing our work but still maintain a research presence. Our two postgraduate students have graduated and we’ll be looking to select a small cohort of new postgraduate students from 2011. The involvement of Earthwatch on St Bees Island has ended. This support was greatly appreciated and enabled the essential foundation data to be collected. We are now working with Earthwatch on a new koala project elsewhere in Australia.
This July trip was our first visit following the March cyclone. The objectives of the trip were (1) to repair any cyclone-damaged data loggers and weather stations, (2) to conduct the annual vegetation assessment with the Queensland Parks and Wildlife Service (QPWS) and (3) to conduct an estimate of koala, goat and swamp wallaby density on the island. There were three teams. Dr Bill Ellis (San Diego Zoological Society/University of Qld & Koala Research Centre of CQ) and collaborator Jason Wimmer (postgraduate student QUT) stayed for a few days to service the bio-acoustic monitors that are recording koala calls at selected sites on the island. Bill’s son, James, assisted this team. From QPWS Dr Rhonda Melzer, Andrew McDougal and Steve Burke measured the growth of vegetation in rainforest, woodland and grassland sites to follow the recovery of the vegetation as the goat numbers decline (by culling over years). The Koala Research Centre team included me, Gabriella Manno (a graduate scientist from the University of Rome) and Mary McCabe (long term koala volunteer and member of the Central Queensland Koala Volunteers). We had multiple tasks. We (Mary and Gabriella) assisted the QPWS team monitor the vegetation, relocated long-term habitat monitoring sites and repaired and down-loaded weather stations and data loggers (Alistair with assistance from Mary and Gabriella) and we undertook an island-wide census of koalas, goats and swamp wallabies. This involved six days of walking throughout the island searching intensively for these animals.
The cyclone has had an impact. There is widespread moderate to severe canopy damage with abundant tree tops on the ground and many entire trees blown over. Four months after the storm the forest has become a woodland in many areas – especially our main study area “the knoll” where there must have been an almost total defoliation of eucalypts. Most of our equipment and sites were undamaged. However, I did lose an entire set of data loggers from one tree rendering an entire year’s data useless. I’ll try and set this experiment up again later this year and see if we can get through the next 12 months. Mary and Gabriella spent a few hours searching the ground around the tree for the five loggers but to no avail. We presume that they have been blown some distance away or have fallen and then been washed away in the cyclonic rains. Despite the storm, koalas are still active and apparently healthy. We heard abundant calls and saw females with advanced young. There was no evidence of disease.
I will be visiting the island again next July and will be looking for a small band of eager and fit volunteers.
The most exciting find on this trip was the discovery of large numbers of seedlings of Eucalyptus tereticornis (Queensland blue gum or forest red gum). This follows last year’s finding of just one seedling. These are the first signs of reproduction of this species we have seen for over a decade. It was believed that the thousands of goats on the island were preventing this tree species from regenerating. Of course the goats were also degrading the ecology of the island generally. However, Eucalyptus tereticornis is particularly important because it forms over 90% of the koala’s diet on the island. If this species disappeared then the koalas would also disappear. The rangers have been working for a number of years to remove the goats. Nearly 3,000 goats have been culled so far and only a few remain. Although we love these beautiful animals their impact on the island was severe. It has been exciting to see the island plant communities start to grow back. The removal of the last few goats will take some years but it is worth it to see the koala habitat return to sustainability.
