While walking the dog in the park this morning, I came across some bare areas of hard-packed dirt that had been broken up, as though by a small pick. Clearly something had done it, it wasn't some geological thing.
The culprit, of course, was a group of Long-billed Corellas. These cockatoos have long points on their upper mandibles that they can use as a lever to get into hard ground.
It's said that this long mandible is also responsible for the red feathers on the bird's bib, giving it the nickname of "cut throat bird".
A few decades ago, the Long-billed Corella was in severe decline in Victoria. But at some stage, one or more of them they discovered that the introduced Onion Grass had corms that were good to eat, if they could be hooked out of the ground.
We don't really know how that information spread throughout the Long-billed Corella population, but these days they're a common bird, even in Melbourne.
They're not popular with all farmers. In Winter and early Spring they can form mega-flocks and descend on farms, making quite a mess. However, I've also heard that they provide much-needed aeration for top layers of soil and scarify the crust, which makes the soil much easier to soak when it rains.
I didn't have one myself, so the photos of the Corella I've attached here were supplied by Greg McLachlan and Chris Brandis through the Birding-Aus newsgroup. Greg's flickr photos are here. Thanks Greg!
Chris' photo shows the bill particularly well, as well as showing what the bird has been doing with it, so I attached it at the last minute. Thanks, Chris!