There can scarcely be an Australian bird more beloved than the Superb Fairy-wren; there’s certainly no Australian bird that has been more studied. The Superb Fairy-wren is an endlessly endearing creature, the most familiar of the nine species of Fairy-wren (Malurus spp) found in Australia. Some measure of the beauty of these tiny birds is suggested by the names of three of them: in addition to the Superb Fairy-wren there are also the Lovely Fairy-wren (Malurus amabilis) and the Splendid Fairy-wren (M. splendens); names alone, however, cannot convey the immense charm of these birds.
Most Fairy-wrens are more colloquially known as “Blue Wrens”, a name derived from the stunning blue plumage worn by adult males during the breeding season. Leading into and out of the breeding season it’s possible to see male Fairy-wrens in mid-moult, the drab brown feathers of winter coming in or out, and a bird at this stage of its life presents a sorry sight: it has a mottled and moth-eaten appearance, with all the dignity of an old winter coat forgotten in the back of a wardrobe. When the breeding feathers fully emerge, though, the birds are – well, lovely. Splendid. Superb.
Outside the breeding season, and when not moulting, male Superb Fairy-wrens are as sweetly unassuming as their female counterparts, with dusky brown plumage that is always immaculate. Only the beak, face, and tail differentiate the two sexes in winter: the male’s beak, in the Fairy-wrens a dainty appendage, is always black to the females’ red; females wear a demure ochre-red facemask over their eyes; and the long, cheerfully cocked tail, which in females is brown, in males retains the vivid deep blue of their breeding plumage all year round, the only part of the animal to do so.
At some stage of maturity, however, males stop moulting out of their breeding plumage, instead remaining in their startling blue uniforms year-round. Is this a blessing or a curse? For a tiny bird such as the Superb Fairy-wren, measuring only fourteen centimetres long and with half of that length being tail, reaching such an advanced age must be regarded as some kind of an achievement: the average life expectancy of a Superb Fairy-wren is only two years. Furthermore, it’s known that female Superb Fairy-wrens find those males who moult into their blue plumage the earliest to be the most attractive, and how could a male don his blue earlier than by never taking it off? However, once a male stops moulting his chances of survival must drop: nothing in the Australian bush stands out quite as vividly as a Fairy-wren’s blue feathers.
So it is a risk. Fair-wrens may forage ceaselessly for insects and other small invertebrates, but they themselves are not so far from the bottom of the food-chain, and perhaps not surprisingly they seem to see predators everywhere. Among the various songs and vocalisations the Superb Fairy-wren utters, there’s a particular song which is made only by the males, and only upon the sighting of a threat: when a predatory bird flies overhead, a male Superb Fairy-wren will fly to the top of the nearest bush, exposing himself while his fellows take shelter, and sing a loud, sustained trill for all the forest to hear. Exactly why he does this is unclear – there are other, entirely different, calls made by both male and female Superb Fairy-wrens to warn of danger, and indeed Superb Fairy-wrens are known to be able to learn to recognise the warning calls of other birds, and react appropriately to them – but it may be that the performance – what else to call it? – allows the male to boast about his prowess, his fitness and fearlessness in the presence of mortal danger. Certainly male Superb Fairy-wrens seem overly eager to announce a “threat”: I’ve seen them launch themselves up shrubs and holler to the sky at the appearance overhead of any bird that looks even vaguely like a Pied Currawong (Strepera graculina) or any of the other birds that feed on Superb Fairy-wrens or on their eggs; most astonishingly, I’ve seen male Superb Fairy-wrens react in this way to the presence of Galahs (Eolophus roseicapilla), which must be one of the least threatening of all Australian birds.
It wouldn’t be surprising if this whole display was done simply in an attempt to impress females: impressing potential mates is a considerable part of most vertebrates’ lives. An animal must find a partner, somehow convincing that individual of his or her fitness; any resulting children must then be raised, and in order to do so feeding territories must be established and defended. However, these are the least of the complications in the Superb Fairy-wren’s breeding behaviour.
Superb Fairy-wrens breed cooperatively, with small groups of birds defending a territory together and each helping to raise any young born in that territory. These groups consist of a dominant, breeding male and female, and a handful of subordinates; at night the birds all roost on a branch tight by each-other’s sides. The subordinates are all males: females, once their old enough, are forced to leave the territory and find a place of their own.
Each of the subordinate birds in the group will have been born in that territory: each is at home. However this does not necessarily mean that each is the offspring of the dominant male: despite males and females forming apparently close life-long bonds, Superb Fairy-wrens are extraordinarily promiscuous, and male and female birds alike will each take whatever opportunity they can find to sneak away from their small territory and mate with their neighbours. So it’s not at all unlikely that a dominant male will raise some other bird’s offspring; all the while, his offspring are being raised elsewhere.
We know so much about Superb Fairy-wrens because the Botany and Zoology Department of the Australian National University in Canberra has the good fortune to be nearly adjacent to the Australian National Botanic Gardens, which takes up a large part of the foot of Black Mountain and which, being planted thickly with Australian native plants from all over the country, is host to a rich array of native birds – not least a large and thriving population of Superb Fairy-wrens. Researchers at the ANU have been studying the wrens for many years; when I was an undergraduate in the department I played my part, too, being led with my classmates to conduct radio-tracking studies on wrens outside the breeding season. The hypothesis was that they would do little, and as we stood outside dense thickets of shrubbery for hours on end, pointing the radio-receiver at the unseen and motionless birds within, the hypothesis seemed a solid one.
What I’ve presented above are only the most basic details of the Superb Fairy-wren’s behaviour. There is much more that we now know about this beautiful bird. Of all the facts about the Superb Fairy-wren’s life that have been discovered over the years, none is more charming than one small detail of the male’s courtship behaviour: while wooing a potential mate, either in his territory or in somebody else’s, a male Superb Fairy-wren will pluck petals from a flower and present them to the female as a kind of bouquet. Whether this increases his chances of mating or not, I don’t know; but it’s hard not to smile at the thought of this tiny, colourful bird carrying such an offering.
The Superb Fairy-wren is neither uncommon nor unusual: if I walk a few blocks from my house to Merri Creek I’ve got a good chance of seeing one, even in the middle of a city as large as Melbourne; if I travel to any other part of Australia, even the central deserts, I’ll be likely to encounter one of its close relatives. Yet this small and in many ways unobtrusive bird has been shown to lead a life of extraordinary complexity and richness. If the Superb Fairy-wren seems more interesting than other animals, it’s only because it’s been more studied; how can we begin to imagine what other lives might be being led, by all the animals we encounter but scarcely stop to consider every single day? There are millions of species of animal on earth, certainly more than we know of, many whose existence is scarcely credible; and animals are only one form of life, and it would be foolish to think that plants, or fungi, or bacteria, are in their way any less extraordinary or fascinating. If one stops to consider for even a moment the astounding implications of this, the overwhelming variety and complexity of life on this planet – I honestly think one would find it literally impossible to feel bored ever again.
Image sourced from http://en.wikipedia.org