R2D2 in black and white

I’ve been spending a lot of time with magpies lately.  “Model magpies” as my nine year old aptly described these two who spent the day  posing in the Japanese maple and prancing around the back deck.  Oddly enough, the companionship steps up in intensity whenever I stop typing for a snack.

This gang of youngbloods don’t spend all their time begging for food and doing catalogue shoots, though.  There’s also the occasional training session for the Olympic synchronised vogueing competition.

And, of course, plenty of carolling.  The juveniles spent a lot of time last week singing for their supper, until one of the grown-ups got jack of the whole thing and flew down to show them how it was done.

But not before the youngsters did their party trick.  In amongst all the mellifluous warbling, my ear caught some distinct moments of robotic squeaking and clacking. The magpies were doing a bowerbird impression.

Apparently Australian birds are uncommonly good at mimicry.  Lyrebirds are famous for it, but all sorts of implausible suspects have a line in impressions as well: magpies, mistletoe birds, silver eyes. Apparently the minute brown thornbill has been recorded mimicking a pied currawong – a bird forty times its size.

Why do birds mimics the songs of others?  Pretending to be something bigger and tougher for self defense purposes seems to be one motive.  Bowerbirds have been observed doing raven impressions while being mobbed by a colony of those rather nasty bell-miners, for instance.

Another seems to be showing off to make yourself look good to potential mates.  Researchers have found that male bowerbirds that can only manage a one or two rubbish impressions (singing “like a kookaburra with bronchitis”, as the researcher cruelly remarked) have less mating success than those who can effortlessly produce a good five.

The most hilarious explanation I’ve read for bird mimicry is to chill out sexual partners.  Researchers reckon that R2D2 style squeaks and clicks that satin bowerbirds make while courting can freak out their mates:

“by interspersing melodic mimetic laughing kookaburra and Lewin’s honeyeater calls between episodes of harsh mechanical calls, males may calm females and improve the likelihood of that females will stay for additional courtship and copulation” (Borgia and Keaghy, 2015)

The idea that a sudden explosion of kookaburra calls would mellow you out and get you in the mood gives me a good picture of why certain male bowerbirds (and possibly particular male ornithologists) might be unlucky in love.

While not as famous as lyrebirds, bowerbirds do some pretty amazing impressions, not just of individual sounds but of whole acoustic scenes.  How’s this, observed from a toothed bowerbird?

A male started with the sounds of a group of people talking as they moved through the forest with their machetes cutting bushes and dogs barking, and continued with the sounds of machetes being used to fell a tree, complete with the rattle of shaking leaves after each blow and eventually the sound of the tree falling and hitting the ground with a crash (Borgia and Keaghy, 2015, 97)

The humble magpie doesn’t do badly either.  They’ve been recorded copying 21 different species of bird, as well as the sound of horses, dogs, cats and humans.  Magpies, it appears, only imitate critters that share their territory, not just the blow-ins and passers by, so it makes sense that our youngsters copy the satin bowerbirds that seem so spend much of the year in the garden, eviscerating my beans and kiwifruit vines and making free with my broken pegs.

I’ve got a whole new agenda in the backyard now.  There’s those in-flagrante males doing kookaburra impressions to listen out for.  As yet, I haven’t found any references to magpie calls appearing in the satin bowerbird repertoire.  Maybe this will be my contribution to science.  Better still, maybe I’ll catch a bowerbird in the act of ripping off a magpie doing a remix of another bowerbird.  Or the other way round.

Additional references

Borgia, G. and Keaghy, J. (2015) “Cognitively driven cooption and the evolution of sexual displays in bowerbirds”in Irschick, D., Briffa, M and Podos, J. (eds) Animal Signalling and Function: an integrative approach, Wiley Blackwell

Kaplan, Gisela (2015) Bird Minds, CSIRO Publishing