Zoo Data Key to Planning Koala Field Season
Posted at 8:40 am July 20, 2007 by Bill EllisHi again from St. Bees Island, where the rain continues to fall. Despite most of Australia being in the grip of a severe drought, the dry weather seems to have left the Mackay area, and St. Bees Island is green and lush. At present I am planning the rest of the koala research field season, and it’s a pretty exciting time for all involved (see post, Island Koalas Keep Us Guessing). But besides the actual research, there are many aspects to planning my fieldwork. I need to move a lot of equipment and pack plenty of food, make sure our research station is available, organize planes and boats, and make sure the other researchers and volunteers are all set to go.
Without a doubt, one of the most important parts of any study of animal ecology is making sure you are there at the right time. As part of the San Diego Zoo’s Behavioral Biology Division, I am investigating the breeding strategies and ecology of a group of koalas on St. Bees Island off the coast of Queensland. Over the last few years, I have collected small tissue samples from over 100 of these koalas, allowing me to DNA fingerprint each one of them. This means that I can investigate which male koalas are the fathers of the young I encounter each year. Koalas are generally solitary animals, so even though the mothers are easy to identify (especially when the joey is in the pouch!), the fathers don’t tend to stay around.
This year, we are turning our attention to the strategies that the individual koalas employ to try to mate with one another. To do this, we need to be on the island at the right time! So, the question for us was, when do most of the matings occur?
A few seasons ago, we were lucky enough to watch one joey, just after birth, climbing into the pouch of its mother–something that usually takes about 45 minutes. We found other newly born koalas on the island, and as these koalas grew, we measured their weight every time we caught them. At the San Diego Zoo, the koala keepers maintain records of all the koalas and weigh and measure the young animals as they grow. The records at the Zoo are naturally much better than anything collected in the wild, because the koalas in managed care can be weighed and measured much more often and much more easily.
Surprisingly (well, we were surprised!) the growth of young koalas at St. Bees Island has been very close to that recorded for koalas at the San Diego Zoo, so we were able to use the San Diego growth chart to plot the age of other joeys when we caught them. As a result, we found that most koalas are born at St. Bees Island during November and December–early in summer for us (the San Diego koalas give birth in the same season, but that is around July in the U.S.).
Koalas have a gestation period of about 34 days, so if I want to know what those koalas that give birth in November this year are doing around mating time, I need to be on the island in October.
Who would have thought that in addition to packing all my field gear and arranging my travel, I would need to consult the team in San Diego to find out when the best time to be on site would be? It just goes to show that all those tedious notes the keepers make every day when they are looking after the koalas at the Zoo really are important. Thanks!
Dr. Bill Ellis is a Conservation Research Postdoctoral Fellow for the San Diego Zoo.
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July 20th, 2007 at 2:14 pm
Thanks, Bill, for the very informative blog on how to strategize your timing for mating season. It is a very exacting science after all, and requires translating the behaviors in the two hemispheres into seasonal activities.
Best wishes. We look forward to more reports on your findings.
August 31st, 2007 at 4:42 pm
My family owned St Bees Island from about 1970 through 1981. They were from Ann Arbor Michigan. They built the cider block house in Home Bay.
The Koalas appeared very healthy during that time. The family worked diligently not to disturb them. Sometimes a young Koala would come up the porch and climb the screen door. My folks would let them in and they would look around, climbing here and there, then they would leave.
The greatest threat to the Koalas at the time was the people that would come out in boats and go behind the island. They would shoot the Koalas. Dad would try to get in his boat fast enough to chase them, but never managed to get around the island in time. i am pleased to hear the island in now a sanctuary. As such, it is also a sanctuary for the sea turtles that come to lay eggs in Home Bay, and all the other wild life.
I hope you enjoyed your visit there. We loved the place and tried to leave it in better condition than we found it.
September 10th, 2007 at 6:19 pm
Hi Anne,
Every time I see the name (Flook) in the cement at the back door of the south house on St Bees Island I wonder what it must have been like for the people who lived there. It is a great place and I can tell you that the koalas are still healthy and doing very well.
The lease has been sold again recently and there are some changes on the island, but the koalas are now secure in a National Park.
Thanks very much for your comment, I know a bit about your family’s connection to the island and if you have any news about the koalas from your time there, or even any stories about the boat wrecks and island characters I’d love to hear them. We still see plenty of Peter Berck, so he has plenty of tales to tell!
Thanks again,
Regards,
Bill
November 5th, 2007 at 3:59 pm
My Mom also wrote a book, as did Peter’s Dad, but Mom’s was never published. I am reluctant to let the manuscript out of my hands, but if you are ever in planning to be in Sacramento, please let me know and I will bring you a copy to borrow.
January 26th, 2009 at 4:14 pm
this is very interesting i really would love to see a joey!! i am doing an animal report on a koala and got a lot of info from here