Sunday, 16 May 2010
I took this photo in south Australia, in an area of parkland containing thinly distributed eucalyptus trees interspersed among low bushes and grassland, not far from the remnant Myrtle Beech forest where I photographed the cicada molt skin. There were several koalas in the area (easy to spot - just look for clusters of tourists with their cameras out), almost all fast asleep save for one who was casually munching away at the eucalyptus leaves. The popular image of koalas is that they live an idyllic life of ease, probably due to the long periods they spend sleeping (up to 20 hours a day). In truth, eucalyptus is such a poor food resource that they need these long periods of rest to digest it - I guess the advantage is that they don't have much competition.
A hundred thousand years ago, there would have been no koalas where I took this photo - the forest would have been a dense thicket of Myrtle Beech, tree ferns, cycads, and other jungle plants, with few if any eucalyptus for a koala to feed on. Koalas came to this section of parkland in south Australia with the eucalyptus forest, and the forest came with the aboriginals. The practice of burning to clear the land pushed back the Myrtle forests, while the eucalyptus thrived in the fire zone. Eucalyptus is highly adapted to fire, being able to both survive and spread after fire sweeps through the forests, while taking advantage of the fire to eliminate competing plant species... and I suppose hungry koalas.