LOOK again when a flock of sulphur-crested cockatoos passes overhead because there might be a crafty white goshawk travelling with them.
My amateur research into the behaviour of white goshawks in my valley has taught me that they can sometimes be found in association with cockies – if not at the heart of the flock, at its fringe.
And what is surprising is the white cockies appear to tolerate these usurpers even though all my bird books suggest that the fearsome predator should be the avowed enemy of a parrot that on paper could provide a big, tasty meal.
When I first discovered the white goshawk (a white morph sub-species of the grey goshawk more common on the mainland) I was intrigued to find them in the company of white cockies, and reached the conclusion that they were using the cockies as cover, or disguise, in their hunt for other species.
This observation has been confirmed in an article in Australian Birdlife magazine which goes into great detail about the problems of a white bird of prey standing out among largely green foliage, and being easily spotted by nervous birds and small mammals.
As the article by John Peter explained, the goshawks have solved the problem of being easily seen by merely mingling with sulphur-crested cockatoos, birds that other bird species and mammals have no reason to fear.
It leaves the question of why the cockies do not protest, and shriek in horror, when the presence of a white goshawk appears among them. The author offers another reason for this.
Goshawks are known to take prey the size of white-faced herons but there is no evidence, anywhere in the country, of a white goshawk ever taking a cockatoo or a corella.
The cockies obviously know this and appear to be grateful for the goshawk’s presence, at least in the knowledge that it will not attack them.
I have another theory about goshawk presence among cockies. It could well be that the goshawks act as a kind of “minder” or bodyguard for the cockies, returning the favour of the parrots offering cover by providing protection. With a goshawk around, the cockies can be assured that they will not be attacked by another goshawk species found in Hobart, the brown goshawk, or even the fast-flying peregrine falcon. Raptors – which always have to be in tip-top condition and free of injury to hunt – are wary of getting in confrontations that are not directly related to attacking prey.
After two centuries of persecution the white goshawk has only started to make a comeback to the Hobart area in the past decade, and has become relatively common
When I first came to live in Hobart 12 years ago I was surprised to note that when white goshawks flew over my garden the resident new holland honeyeaters did not let out an alarm call as they did with other birds of prey. Obviously, because the goshawks had not been seen for so many years, the honeyeaters did not recognise them as a threat.
All that has changed in the intervening years as goshawks have shown their hand – or should I say talons. A more tolerant attitude towards goshawks – particularly among people who keep a favourite goshawk food, chooks – has allowed the raptors back into our lives, even if the honeyeaters might not be too pleased to see them return. When they spot a goshawk, the honeyeaters dive for cover – that’s if the raptor is not posing as a sulphur-crested cockatoo.