We heard the first bellow on St. Bees Island, Australia, at 5:30 p.m from the Rain Forest Gulley (See Jen's blog, Motorcycles and Koalas). The next one came from the Knoll, then the South House Gulley, and back at the Rain Forest. About every minute or two we could hear the koalas calling to each other. What was going on?

We went to St. Bees to try to learn more about bellows (see Fred's blog, Where Have All the Koalas Gone?). Koalas are most active around dusk, so we set off from our base camp in late afternoon in order to do a " playback experiment." These types of studies involve broadcasting sounds to animals in order to then record their responses and learn more about vocal communication in the natural habitat. Jen was in charge of playing the sounds and recording responses, a skill she had picked up while studying the koalas at the San Diego Zoo.

The rest of the Zoo team (see photo) had other assignments. Richard kept tabs on Digger, an adult male, who was jumping around in a tree and bellowing for all to hear but, apparently, not in response to the recorded bellows from the Zoo koalas. Carmi focused on a young male, who seemed to be watching Jackaroo, an adult male with a radiocollar that Bill was following as he left a tree near Digger (see Bill's blog, Koala Field Project: Tracking Koalas). Chris took notes on Ware, an adult male who perked up his head to listen to our calls, but then returned to his afternoon siesta. Bob and I followed Olivia, an adult female, as she trucked through the thicketed underbrush, sniffing some trees as she moved. As soon as the first call was played, she scrambled about 50 feet (15 meters) up a tree. After that, she listened a bit, but pretty much munched on some leaves for her early evening snack.

Jen had recorded a very deep bellow by Jackaroo, one of the adult male koalas living on the island, in response to a playback earlier on our trip. We heard a lot of bellows from koalas on the island, and the sounds were coming from just about every direction. But the calls were too far away for Jen to record on this night. When koalas around the island bellow to each other, it sounds like a " koala chorus." We think that koalas have a more intricate acoustic communication system than most people realize and intend to continue our work in the field and at the San Diego Zoo in order to learn more about koalas.

Fred Bercovitch is the division head/senior scientist of Behavioral Biology/CRES.

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