One of the nicer things about being a wildlife carer is the opportunity to get to know your charges in a depth that can’t really be matched by simply watching them in the wild, or while in permanent captivity. Who’d have guessed that flying foxes have complex personalities, ranging from the fearful and apprehensive to the outgoing and approachable? Or that magpie geese are among the smartest birds around?

You also get to see how other creatures interact with your charges, constrained though that is by enforced captivity. For us, this includes having the occasional sea eagle, wedge tailed eagle or rufous owl hanging about looking for an easy feed of flying fox. It also includes having the very persistent attention of a collared sparrow-hawk that seems fixated on attacking and devouring magpies.

A bird killer by preference, collared sparrow-hawks are among the lightweights of the raptorial world. They weigh in at an average of 126g for males and 218g for females, and are alleged to prefer prey of around 100g, occasionally venturing to as much as 200 g. That puts crested pigeons and spotted bowerbirds near the upper weight range of their preferred dietary species according to Debus et al. 1993. Olsen et al (2018) noted the sparrow-hawks hunt juvenile magpies on occasion. Other prey items, such as insects, lizards, micro-bats and the odd ground mammal are much smaller.

Under these circumstances, it comes as a bit of a surprise to find at least one collared sparrow-hawk is a determined hunter of adult magpies. To set the scene, it would help to contemplate the process of raising and releasing orphan magpies. After a time of intensive feeding, cleaning and keeping warm, the birds graduate to a large cage where they can learn to fly, socialise and forage for wild food. They also learn the significance of alarm calls uttered by other species of bird and begin to respond appropriately to avoid snakes and the omnipresent kites. They also learn to utter their own alarm calls, which are made with great urgency when the sparrow-hawk turns up.

Turning up, in this instance, is a euphemism for flying into the side of the cage at full speed, in the expectation of catching a magpie unawares.  When the sparrow-hawk can’t get through the side of the cage, it hops around on the top and even comes to the ground in search of a way in. Needless to say, the magpie is not impressed by being potential sparrow-hawk food and vocalizes wildly, at which stage we rush out to intervene. Even then, the sparrow-hawk flies nonchalantly off to a nearby perch and tries to wait us out. It eventually gives up and peace returns.

Attacks on the caged magpies are not just bluff. On three occasions we have seen sparrow-hawks kill and eat fully grown magpies that had been released months previously and were prospering in the wild.

All this suggests that sparrow hawks are more ambitious hunters than they are given credit for in the literature and might, in part, account for the relative scarcity of magpies outside the artificially favourable habitat provided by urban areas. Even so, sparrow-hawks are relative amateurs when it comes to attacking large prey – the peregrine falcon which managed to kill an ibis in our back yard in South Townsville sets an altogether higher bar in the ferocity stakes.

References

Debus S.J.S., Ley A.J., Tremont S.M., Tremont R.M. and Collins J.L. (1993) Breeding behaviour and diet of the collared sparrowhawk Accipiter cirrhocephalus in northern New South Wales. Australian Bird Watcher 15: 68–91.

Olsen, J., Judge, D., Trost, S., Rose, A. B., and Debus, S. J. S. (2018) Diets of breeding Brown Goshawks Accipiter fasciatus and Collared Sparrowhawks A. cirrocephalus near Canberra, Australia and comparisons with other regions and raptors   Corella 42, 18-28