The San Diego Zoo is supporting one of the longest-running ecological studies of koalas, at St. Bees Island in central Queensland, Australia. So, most of my reports concentrate on the behavior of this healthy and undisturbed population: how the young koalas are doing, which males are on “the knoll” and whether Elizabeth has had another baby, etc. However, not all koala populations are doing as well as ours, and I also spend a good deal of time in Central Queensland and in Southeast Queensland, assisting other researchers in their work. In Southeast Queensland, the situation is very different from St. Bees Island (see previous post Island Koalas: Meet Orbit).
The koalas around Brisbane, some 1,000 kilometers (620 miles) south of St. Bees Island, are in serious decline. Recent predictions based on detailed field surveys indicate that as few as 2,000 koalas remain from a formerly large and healthy population in the southeast. These koalas occur in fragments of bush that persist among new housing developments and in small patches of bushland that have been left to try to preserve habitat for them and other animals. Many koalas turn up in suburban back yards, and sadly, a lot of the koalas end up being injured (or worse) as a result of encounters with cars and dogs.
Despite koalas spending most of their time sitting in trees, they climb down to move between trees at night, and this is when they are in the most danger. I have been helping some researchers from the University of Queensland who are investigating how koalas use their small patches of habitat and whether there are any ways we can make their daily travels more safe. In some locations, large road underpasses have been built to allow koalas to move safely from one side of the road to the other, and the researchers I’m helping are tracking koalas to see whether they use the crossings and what features should be included in the crossing structures to help the koalas.Last week we caught several koalas to collect their GPS collar data, and one of the koalas we caught had a bad case of conjunctivitis, caused by chlamydial infection. Koalas at St. Bees Island, while appearing healthy, also have chlamydial infection, but we rarely see sick animals, and our conclusion is that the stress of living in the city might be a reason why more koalas in the southeast seem to show signs of infection than elsewhere. If the koalas in the southeast are under more pressure from loss of habitat, overcrowding, and having to deal with dogs and cars, then maybe they are less able to fight off the infections that don’t really affect other populations in the same way.
Working with this team has convinced me that our work on St. Bees Island is critical to the future of koalas in Queensland. While I am doing my best to help the investigation of koalas under serious threat, it is good to know that we can also learn some basic information about koala ecology from a reasonably healthy group that is not under the same sort of threat. In the future, groups like the St. Bees Island koalas might be the only populations from which we can learn about koala reproduction, physiology, and general ecology, so they are vital to the future of the species. I hope that St. Bees Island doesn’t end up as an “ark,” housing one of the last viable populations of koalas in Queensland, but if it does, at least we will know enough about these koalas to make the right decisions to ensure they do not go the same way as their southern counterparts.
Bill Ellis is a Clark Endowed Conservation Research Postdoctoral Fellow for the San Diego Zoo.