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Canberra-based naturalist, conservationist, educator since 1980. I’m passionate about the natural world (especially the southern hemisphere), and trying to understand it and to share such understandings. To that aim I’ve written several books (most recently 'Birds in Their Habitats' and 'Australian Bird Names; origins and meanings'), run tours all over Australia, and for the last decade to South America, done a lot of ABC radio work, chaired a government environmental advisory committee and taught many adult education classes – and of course presented this blog, since 2012. I am the recipient of the Australian Natural History Medallion, the Australian Plants Award and most recently a Medal of the Order of Australia for ‘services to conservation and the environment’. I live happily in suburban Duffy with my partner Louise surrounded by a dense native garden and lots of birds.

Thursday, 25 November 2021

Woodswallows, the original grey nomads?

A long time ago, a popular 'getting to know you' game involved a series of  'if you were type of a XXX, what would you be?'. Seems a bit quaint now, but maybe it's still played? Anyway, in my circles at least XXX usually came round to 'a bird'. My answer would usually be 'a woodswallow, because they wander the great inland plains of Australia' - I was then a romantic too. I was also somewhat disingenuous, as only a couple of the six Australian species actually do that, but the person I was talking too probably wouldn't know that. (These days, if asked my favourite bird, and believe it or not it happens, usually on radio, I say 'the one I'm looking at', which is pretty much true, even if unsatisfactory to the enquirer.)

Firstly, and because this is Australia where such confusions in bird names are common, woodswallows are not swallows! From the early days of the Sydney colony the name Wood Swallow was used to distinguish them from 'real' swallows. Their only connection is that both bird groups are superb aerialists, making a living by snatching small insects out of the air. George Caley, the early Sydney botanical collector who reported to Sir Joseph Banks in London, noted that ‘Their resting places were on the stumps of trees which had been felled’, which seem to have spurred the 'wood' part of the name. After a while however many people failed to see the point of this distinction, so for the next century they were just lumped with 'other' swallows. Confusing indeed. 

White-breasted Woodswallow Artamus leucorynchus, Toompine, south-west Queensland.
The silvery-blue black-tipped bill is typical of woodswallows (and of the rest of the family), as
is this habit of perching in the open to watch for passing flying insects.
I also reckon that they typically look very alert, like this, but I guess any bird that survives has to!
So if not swallows, what are they? We now know that they are in the same family as the much bigger Australian magpies, currawongs and butcherbirds, which in turn is an old Australasian family, going back perhaps 45 million years. While we think of that as a recent revelation, in fact it had been suggested long ago. Back in 1907 a connection between woodswallows and Australian magpies had been suggested by William Pycraft of the British Museum; this was largely ignored, but eventually confirmed and extended to currawongs and butcherbirds by Allan McEvey in 1976. McEvey, from the Museum of Victoria, based his conclusions on skeletal studies (as had Pycraft 69 years previously). In particular he noted, uniquely among Australian passerines, a shared strange extension of a cheek bone – a ‘bifurcated zygomatic process’ if you’re that way inclined. For the intervening 70 years however the best Australian ornithologists were admitting they had no idea where woodswallows fitted into the bigger picture. It took the pioneering DNA-DNA hybridisation work of US ornithologists Charles Sibley and Jon Ahlquist in the late 70s and early 80s to settle the question.

Black-faced Woodswallow Artamus cinereus (and orb spider), west of Winton, central Queensland.
This is an inland species, found throughout the continent except for the moist south-east,
but not one of the wanderers.

There are eleven species of woodswallow, all in the same genus, and six of them are Australian. One of these - the White-breasted Woodswallow above - is found as far north as Malaysia and the Philippines. Most of the others are restricted to New Guinea, plus one each in Sulawesi and Fiji.

White-breasted Woodswallow on a wet tropical morning from a hotel window in
Kota Kinabalu, Malaysian Borneo.
The Latin name for the group, Artamus, is a somewhat curious one too. It's Latin for a butcher, or murderer. Seems a bit extreme, though they certainly do away with a lot of insects. But if I was one of their bigger relatives, like a currawong or butcherbird, with a tough reputation to uphold, I might be a bit put out that my little cousin had that fearsome name, while mine translated as 'loud-mouthed' or 'noisy' in both cases! (Strepera for currawong, Cracticus for butcherbird). It comes down to history. In 1771 Linnaeus himself placed the White-breasted Woodswallow in the Old World genus Lanius, the shrikes. Lanius itself is another word for butcher, so when the esteemed French ornithologist Louis Vieillot recognised the error and gave woodswallows their own genus in 1817 he used another 'butcher' word, Artamus. Whether he did this out of respect to Linnaeus, or because he also thought they were shrike-related, is unclear.
Dusky Woodswallow A. cinereus delivering a butcher's meal to chicks
in the nest, Canberra.
Not all woodswallows however go to the trouble of catching their own meals. Kleptoparasitism (what a wonderful word!) is practised by at least a couple of species, and thus probably more. This means stealing someone else's food, and observations have ranged from a White-browed Woodswallow snatching food from a much bigger Black-faced Cuckooshrike about to deliver it to its chick, to various stories of Dusky Woodswallows mugging a range of smaller birds for their hard-earned meals.
This female White-browed Swallow A. superciliosus is definitely catching her own food,
in the form of this locust on the streets of Karumba, far north Queensland.

However there is another, also fascinating, aspect of woodswallow diet. As well as being primarily aerial insectivores, they also forage on nectar and pollen, even to the extent of having evolved brush-tipped tongues like honeyeaters. It seems that they could be important pollinators of some inland plant groups, though I'm not aware that this has been much studied. While all Australian woodswallows sup on nectar from time to time, only the inland nomads, the White-browed and Masked Woodswallows, do so regularly and across their range. But this tongue is a very sophisticated and specific tool, taking up liquid by osmosis like a paint brush, so why is it possessed by species which seemingly rarely use it? Perhaps the ancestral woodswallow was much more nectar-dependant, before its descendants diversified into chasing insects across the skies? If so, why retain it if you're not using it? It's all very satisfyingly puzzling.

Female White-browed (above) and male Masked Woodswallow A. personata hanging out, as
these species often do, at Cobbold Gorge Station near Georgetown, northern Queensland.
The relationship of these two species is another delicious puzzle. They are the only two woodswallow species which specialise in wandering across the vast arid inland plains, following the rains and resources, though drought will bring them closer to the coast to breed, including in Canberra. A thunderstorm in the dry country is likely to bring big flocks of these birds, along with swallows, martins and, in summer, swifts when they are visiting from the northern hemisphere, to feast on the insect hosts caught up in the turbulence. 
 
These woodswallows are usually found in mixed flocks, calling down from the skies. Their calls are indistinguishable to our ears but given our poor aural acuity this doesn't mean much. Significantly and most surprisingly however their mitochondrial DNA cannot be reliably distinguished either. This is not unexpected in species which have only recently separated, but in that case we would expect them to be isolated geographically, or to interbreed readily. Neither is the case here. They often breed in mixed colonies, but rarely if ever form a mixed pair. Most peculiar. Those much more erudite than I cannot explain this situation. Here are some typical flocks of these two species.
White-browed and Masked Woodswallows often gather in large numbers on exposed
branches, flying out to harvest insects. This image and the next are also from Cobbold Gorge.
Masked and White-browed Woodswallows coming to drink at a waterhole.
(And a bonus Budgerigar for the sharp-eyed reader.)
Even this is interesting, as insect-eaters often find enough moisture in their food
and don't need to drink.
Part of a huge flock of these species in western Queensland.
One difference between these two nomads is that Masked Woodswallows are much harder to pin down in a photograph in my experience, but of course that's likely just to be me and is not a reliable taxonomic character! In both species the sexes are distinctly different (which is unlike the other Australian species where they are indistinguishable), the females being a washed-out version of the sharper males.
White-browed Woodswallows during a relatively rare breeding event in Canberra,
at Mount Ainslie NR. Female above, male below.
The most familiar inland woodswallow is the Black-faced, which doesn't seem to move around much, but is spread across the entire continent except for the moist south-eastern strip, coming to the coast especially in the tropics. I love seeing the first ones as we drive west or north-west, as it means we've reached 'the inland' which we love. They are common on the power lines.
Black-faced Woodswallow, Great Sandy Desert, Western Australia.
The least familiar of the Australian woodswallows is the Little Woodswallow, which is rather like a small chocolatey version of the Dusky Woodswallow. I suspect that it isn't that scarce, but it lives where there are relatively few observers, especially in association with cliffs, ranges and rocky outcrops. 
Little Woodswallows A. minor, West MacDonnell Ranges, central Australia.
The snuggling behaviour is common to most woodswallow species - in fact there are
plenty of accounts of up to 200 woodswallows clustered together, clinging to the bark
of a tree, to spend the night. Such roosts have also been reported during the daytime,
even on warm humid days, so it's not primarily about keeping warm.
Yet another sweet woodswallow mystery.
In the south-east the only regular woodswallow is the Dusky, which arrives every spring to breed here from its wintering grounds in Queensland - that is, it is a migrant rather than a nomad. In Canberra it is very familiar in the hill reserves of Canberra, around the urban lakes and in the lower slopes of the ranges, though I don't often see it over suburbia. It has a very distinctive silhouette, with diamond-shaped wings as it soars out from a perch to catch its next snack.
Dusky Woodswallow by Lake Burley Griffin, Canberra.
Dusky Woodswallow feeding chicks, Canberra. This site, in an upright broken spout,
is typical of the species, though other species have other preferences.
The white wing edges and tail tips are prominent in flight.
White-breasted Woodswallows are especially smart I think (speaking only of their attire, not their intellect). They are found throughout the eastern inland, west to central Australia, and are found around the northern coastline from about Sydney to Shark Bay in Western Australia. Inland they are nearly always associated with water. 
White-breasted Woodswallows, Winton, central Queensland.
These photos were taken just a few seconds apart, and I loved the sudden switch of
focus to their right as something caught their attention.
White-breasted Woodswallows at Neweys Reserve, Cobar, central western NSW.
They are especially snuggly, even for woodswallows.
It's hardly a secret - especially now - that I'm a huge fan of woodswallows, old Australians which I find especially characterful. I hope you enjoy them too, and that maybe I've even given you a couple more reasons to do so. Enjoy summer (or winter, depending on where you are).

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4 comments:

Deb Carraro said...

Enjoyed this post, Ian. Thank you.

Ian Fraser said...

Thanks Deb, I always appreciate feedback. And aren’t they a delight?,

Kath H said...

I didn't know so many things about wood swallows! Thanks for informing, and entertaining me. Wonderful photos too.

Ian Fraser said...

Thanks Kath, that pleases me no end! So glad you enjoyed it, and thanks for being such a loyal reader.