The Department of Primary Industries (DPI), Forestry Corporation of NSW (FCNSW) and the Port Macquarie Koala Hospital are working together in the State Forests around Port Macquarie to get a better picture of how koalas live in the forest through a GPS tracking project. Dr Brad Law from DPI and Chris Slade from FCNSW talk to us about how the research is progressing.
Brad, tell us about the project and what you are studying.
We are using GPS collars on koalas to track their movements in State Forests, to understand how koalas use the landscape just a few years after it has been harvested for timber. For example, do they prefer ridges or gullies and where the koalas go when it’s hot. We also want to learn more about the different tree species and sizes of trees koalas use, and whether they use different trees for browsing or resting. An important part of the research is understanding the effectiveness of the protections that are put in place when timber harvesting occurs in State Forest. The research has been going for about six months now, and we have four koalas giving us real-time information on how they are using the forest.
Chris, how do you get the GPS collar on the koala; is it hard to keep the koala calm?
After the koalas have been safely captured, using an enclosure and cage trap that we set up at the base of the tree, we transport the animal to the Port Macquarie Koala Hospital for a check-up. Depending on the time of capture, we have dropped a koala in at 2am, the koala is placed under anaesthetic to enable Cheyne and the wonderful staff at the Koala Hospital to assess the health of the koala.
After they have been checked, the fitting of the collar occurs. The collar is designed with a small section of material that will disintegrate over time or break if stretched too far, to prevent the collar being caught by a stick or branch. The koalas remain calm during transport, with the trap or carry basket being covered by a sheet, and each koala is returned to the same trees from where they were caught.
Brad, what have been your observations so far with where the koalas have been?
It’s probably not unexpected, but the koalas have surprised us a bit with what they have been doing. Each koala is a bit different; we have found some of them using areas away from gully lines over the summer months when we expected them to be there. This was even during quite a hot and dry period. Some koalas also regularly used small trees in the stand regenerating after harvesting over summer, especially shady turpentines. We can’t wait to see what they do in winter.
We have found them feeding in both the regenerating areas and areas that have been excluded from harvesting, so it may be that a mosaic of tree ages in the forest is important to koalas. But it’s still early days, and we have plenty more to learn.
Chris, you talked about koala health. How do you ensure the koalas are healthy before they are released and during the project?
The Koala Hospital screens each of the individuals as they are captured. Swabs and blood are taken as part of a full health screening, which also includes an ultrasound to assess for symptoms of Chlamydia and other diseases. Two of the koalas we captured had conjunctivitis due to Chlamydia infection and were admitted to the hospital for a short stay to receive treatment. Both were treated successfully and released, free of disease, back in the forest. The koalas being tracked are checked daily for the first week after being released and then periodically after that, and we have noted that they all are happily moving about the forests.
Brad, what other koala research have you been carrying out over the past couple of years?
While the GPS tracking allows us to look at fine-scale habitat use by koalas, this has built on our recent research that looked at larger, regional patterns of occurrence. We used acoustic sensors to record the presence of koalas in a survey of the hinterland forests of northeast NSW. This covered a vast area of almost two million hectares (about the size of the country Wales).
What we found was that, unexpectedly, koalas are more widespread in these forests than people had previously thought. We also looked to see whether timber harvesting affected their occurrence, but we found no evidence for this.
Instead, elevation was the main driver, with koalas much less likely to occur at higher elevations along much of the tablelands of northern NSW. Other factors like site productivity (fertility) and recent wildfires also had an influence on koala occurrence.
Chris, the question everyone has is what’s it like working with koalas – are they as soft as they look?
It is fantastic to be involved in the project collaborating with Brad and the DPI team and Cheyne and the Koala Hospital. It is wonderful to go out to the forest with the mystery of where they will be each morning and seeing their interactions. I found two of our males in the same tree recently, which was a great surprise, watching them eye each other off.
Koalas are an amazing animal, so beautifully adapted to the Australian environment. They are as soft as they look and have the softest paw skin you can imagine. They are still a wild animal though, so we treat them with the utmost respect.
Brad, what are your future plans for continuing with this project?
We want to track koalas over a full twelve-month period, to see how the use of their habitat changes with the seasons.
We also want to increase the number of animals that are tracked. This will give us a much more comprehensive picture of how the koalas are using the forest after harvesting and how management practices designed to protect koalas can be improved.
We are also continuing our acoustic sensor work, using the sensors as a way of monitoring trends. We now have four consecutive years of data for the northeast forests, and we would like to continue this into the future. That way we can be more confident about how the koala population is changing over time.
Photos Bronwyn Ellis