Are Currawongs Always Wong?

I wrote this very recently for the Canberra Ornithologists' Group newsletter Gang-gang (http://www.canberrabirds.org.au/); it occurs to me, given the passions that Pied Currawongs can inspire in eastern Australia, that it might be worth offering it to a wider audience as well. I've edited it very slightly to take into account the different context.

......

The boldly staring eye is one of the first things people remark on. The heavy straight business-like beak with the wicked little hook on the end suggests, quite rightly, deadly purpose. Most of their hunting is for invertebrates, searching carefully, stopping to listen and relentlessly pursuing small prey under loose bark and in crevices, hammering at surfaces with that powerful beak. Vertebrates feature quite heavily too however, and grisly stories abound, if we choose to interpret them that way. Eye witness accounts refer to a persistent assault on the feet of a large Green Tree Frog until it fell to the ground, was seized and eaten as it was held down; another tells of a pair working as a team to harry a Feather-tailed Glider. It is understandable if people were shocked at seeing one hurtle into a family of Superb Fairy-wrens and seize the blue male, or select a male Scarlet Robin from a mixed foraging party. Accounts are numerous of eggs and nestlings taken. Are you nodding grimly? Sorry, what was that – currawongs?? No, no, I was talking about Grey Shrike-thrushes, generally one of our ‘favourites’. 

If you’re suggesting that it’s not the same thing you’d be right – in fact unlike shrike-thrushes, currawongs are primarily fruit eaters, at least outside of breeding season. (We normally use ‘currawong’ in the south-east mainland to imply Pied Currawong, but the comments here are generally applicable to the other species as well.) Overall they are truly omnivorous, but even so most of their meat is in the form of insects; their favoured prey is phasmids, the big stick insects which in numbers can defoliate eucalypt forests. In particular they favour the big-bodied gravid female phasmids, for which a million eucalypts are doubtless grateful, in their quiet way.

OK, of course I’m trying to make a point here. We have favourites, in almost any facet of life, which is fine as long as we acknowledge our biases, at least to ourselves. It’s understandable that we should get upset that ‘our’ nests are raided in our yards that we’ve set up to protect wildlife. On the other hand, everyone loves blue wrens, but they can slaughter hundreds of native animals, including babies, in our garden every day. So, our concern for birds preying on other animals, including baby ones, does not extend to insects. Our bias here is almost entirely towards other vertebrates.

The really important difference between currawongs and shrike-thrushes in this context is simply one of abundance. If shrike-thrushes were present in flocks, searching the shrubbery for nests, we may well turn our animus towards them and feel benignly towards the occasional cheery Pied Currawong we encountered. We’ve done two things here (and make no mistake, this one is primarily down to us). Both are due to the fact that we’ve improved conditions for currawongs in Canberra, primarily by planting exotic berry-producing shrubs like Cotoneaster and Pyracantha species. These produce fruit mostly in autumn and winter, providing a reliable food source at what would normally be a tough time of year, and there is little doubt that this allows currawong populations to remain higher through winter than would have been the case in pre-European times.

Furthermore until recently virtually the entire Canberra Pied Currawong population headed for the hills in spring to breed in the mountains. Even in the early 1980s a begging currawong in Canberra was a most unusual occurrence. In 1976 the surprisingly impressive Readers Digest Complete Book of Australian Birds commented that “very few people have ever seen their nests”, a statement that seems ludicrous today. Now, while many Pied Currawongs do still breed in the mountain forests, very many also breed in the same suburbs where they spend winter. There are two implications of this dramatic behavioural change. The period when growing baby currawongs want lots of protein to get them established (like most other chicks) is the time when currawongs prey most on vertebrates, including nestlings. Formerly this harvest took place out of sight and largely out of mind, but suddenly it was happening right in our faces. A secondary implication of this was that the menu in suburbia was rather different from the mountain fare. Up there, discreetly hidden away, all the nestlings taken are of native species; in suburbia a good proportion are exotics such as Feral Pigeons, Starlings, Blackbirds and Common Mynas. Overall the proportion of currawong diet which comprises native birds has undoubtedly fallen in recent decades (though the higher number of currawongs must also be considered).

Our concern with currawong diet is not new, though the focus of the concern has changed. Alec Chisholm, in his column in the Argus of 27 October 1934, reported that the Brisbane Pest Destruction Board from 1925 to 1934 paid (the bounty is not recorded) for the carcases of 55,204 ‘Scrub-magpies’ (ie Pied Currawongs). Their crime is not described, but I assume it was for pinching fruit rather than for the killing of other birds (after all they also paid out for 171,541 starlings and 443,913 sparrows). Various early writers listed a wide range of food taken to which they were not welcome, including raisins on the drying rack, quinces, olives, maize (after stripping off the covering) and chook eggs, as well as insects which were not begrudged. References to nestlings are very scarce.

I don't expect to change any minds by a mere opinion piece. But if it encourages someone to re-examine the nature of a bias, it will have been worth while. Birds are just what they are - only we judge them as being right or wong.