WARNING: A long posting coming up. If not interested in lyrebirds, delete
now!
Howard Plowright, Wed, 26 Sep 2001, wrote:
>
> The topic of mimicry by birds of "common" human produced
> sound has once again been raised - I have a solid report of
> Starlings reproducing the screams of young girls in a school
> playground.
> I'd be very interested to have comments, from within
> Australia, of definite instances of mimicry by starlings or
> other birds of say telephone rings, or other noise related
> to human occupation. From a personal viewpoint I can't say
> I have ever noticed recognisable mimicry.
>
This question commonly arises in connection with lyrebirds. They are often
credited with mimicking mechanical noises of human origin. In considering
this question, it is important, at least where lyrebirds are concerned, to
distinguish between breeding season and non-breeding season song.
The late Norman Robinson of CSIRO Wildlife, studied Superb Lyrebirds for
some 30 years. I have studied Albert's Lyrebirds for a similar period. We
both made hundreds of hours of tape recordings of lyrebirds breeding-season
vocalisations. We did not find a single example of a lyrebird imitating a
mechanical sound of human origin - with one possible exception that I will
come to later. Both species commonly do perfect imitations of the sound of
feathered wings, of beak-snapping, of a beak being tapped on a branch, and I
have a recording of a Superb in Girraween NP (in Qld., just north of the NSW
border) making a noise which could well be an imitation of the creaking of
two branches rubbing together in the wind. But those are all natural
mechanical sounds.
The David Attenborough "Life of Birds" series had a Superb Lyrebird
mimicking a camera motor and a camera shutter, but that almost certainly was
a captive bird and has to do with the way lyrebirds learn to sing. A young
male lyrebird copies the older males that he hears around him. In a zoo
situation, where there is no surrounding population of lyrebirds, a young
male is likely to copy some of the sounds he does hear.
A male Albert's Lyrebird once mimicked the sound of a tractor starter-motor,
immediately after the tractor made the noise. A perfect imitation but he
did it only once. Never again. That happened on my parents property on
Tamborine Mountain (southern Queensland), but was out of the breeding
season. That particular individual moved into our patch of rainforest after
the breeding season each year. He was never there during the breeding
season.
A friend and fellow-sufferer from 'lyrebird addiction' :-) has given me a
recording of an Albert's Lyrebird along the Border Track from O'Reilly's in
Lamington NP (southern Qld) in which the bird mimics human speech. Mostly
there are no recognisable words, but it is unmistakably an imitation of
human speech. And twice he gives a clear "Hey Bill" as of a person calling
for Bill's attention. But again this was outside the breeding season.
I should perhaps emphasise that although many species of Australian birds
are known to mimic, very few use mimicry as an integral part of their
breeding season song. Tooth-bill Bowerbirds do so quite extensively; Satin
Bowerbirds to a lesser extent. I don't think Regent Bowerbirds do at all,
and I have no experience of the other species of bowerbirds. Albert's
Lyrebirds, most remarkably, weave their mimicry into a stereotyped "song" of
some 40 to 50 seconds long, which may be repeated many times. The sounds
always come in the same order. (Superb mimicry appears to be in random
order.)
Now to return to the possible exception. Back in the 1920s, a Superb
Lyrebird chick was taken from the nest and raised with the domestic hens by
a farmer in the Dorrigo district of NSW. It couldn't hear other lyrebirds.
It could hear the farmer's son practising his flute. So those were the
sounds the bird learnt to sing - with the sound quality of a flute. Later
the bird was released back into the wild and his flute sounds became the
territorial songs for that population, and have been culturally passed down
the generations since then.
In 1978, I visited the area. The N P Ranger for the district took me to the
site of the farm house (by then removed, but the stumps remained) where the
lyrebird chick had been raised, and then to the existing population of
lyrebirds. I tape-recorded them, and the sound certainly fitted the story.
Its veracity has been questioned however, on the grounds that the same
"flute-sounding" territorial songs have been recorded 100 km to the south.
Yet it seems possible that in 70 years the songs could have been culturally
transmitted that distance.
If that story is true, then the lyrebirds have been mimicking a mechanical
sound of human origin: a flute! And in case anyone thinks to argue that no,
they are not mimicking a flute, only the original captive bird did that, and
the rest are just "mimicking" other lyrebirds, I must point out, that that
is what happens with virtually all lyrebird mimicry. A lyrebird is not
copying a sound he hears another species making, he's copying sounds older
lyrebirds are making. How do we know this? Lyrebirds were introduced into
Tasmania in the '30s and '40s. For decades afterwards they still mimicked
whipbirds and pilot-birds - sounds that the original 'transportees' brought
with them, of species that do not occur in Tasmania. And further, all the
Albert's in any one locality have the same stereotyped sequence of mimicked
sounds - clear evidence that it is culturally transmitted.
Remarkable birds, are our lyrebirds. The Albert's is possibly the only wild
bird in the world to accompany its song with a musical instrument. But
that's another story and has nothing to do with mimicry.
Cheers
Syd Curtis in Brisbane, Qld.
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