I first noticed this kookaburra because a Grey Butcherbird was sitting on the branch above, watching it intently. Not much escapes a bird’s attention. The kookaburra had caught a rat and was struggling to stay in balance with such large prey dangling from its bill.
The rat (a common introduced Black Rat or Roof Rat, Rattus rattus) was clearly dead. For at least half an hour the kookaburra continued to vigorously whack the rat’s body against the branch. As anyone who has watched a kookaburra knows, this is how they immobilise and kill their prey. However, they often continue the behaviour well after the prey is dead, like this one was doing with the rat.
Why would the bird waste so much time and energy when the prey is well and truly lifeless? I’m sure it’s not just overkill. The reason for the continued bashing is surely to prepare the prey for eating, to tenderise or pulverise it and perhaps break it apart. In addition, it manipulates the prey back and forth in its bill — as smaller birds sometimes do with caterpillars to make them mushy inside.
A kookaburra doesn’t have powerful talons for capturing or a hooked bill for tearing prey apart, like a raptor does. Instead, its has a large straight bill and strong neck muscles attached to a special bony ridge at the back of the skull, which enable it to beat its catch with great force. The photos above and below show the bird rotating its head as it whips the prey onto the branch. There’s an audible whack as rat strikes tree.
The Laughing Kookaburra (Dacelo novaeguineae) is one of the largest kingfishers in the world. ‘Kingfisher’ is a misleading name for this colourful group of birds because most species are not primarily fish-catchers, but live and hunt in forest or woodland. Kookaburras are in that category. The Laughing Kookaburra’s diet includes large insects, lizards, snakes, frogs, small birds, mice and occasionally, if it has the opportunity it may dive for fish. Rats are not unheard of but are certainly toward the larger end of the size range.
I watched the kookaburra for more than 30 minutes. When I left it was still grasping the rat in its bill and bashing it onto the branch, making no attempt yet to eat it. I have no idea how long this continued.
It reminded me of the time a few years ago when I saw a kookaburra flinging a carrot against a branch. The carrot must have escaped from nearby picnickers before being ‘captured’ by the bird — and I dare say it probably didn’t put up much of a struggle. However, no amount of whacking would turn it into a meal fit for a kookaburra, though the bird certainly tried its best.
The kingfishers that don’t fish by Paula Peeters, Paperbark Writer (includes a delightful cartoon illustrating the kookaburra’s famous laugh).