Thank you Vicki Powys and David Geering for confirming that the Attenborough
camera-shutter mimicry was from a captive lyrebird. (My apologies, David
for deliberately maligning (in another posting) the Park Service's Washpool
Superbs.)
David wrote (28 Feb 2003):
>
> This was a captive bird at Healesville Sanctuary in Victoria. This bird
> was apparently well known for picking up all manner of frequently heard
> noises such as the motor drive of cameras.
Lyrebirds (both species) learn their mimicry by copying older lyrebirds, not
by copying the other species directly, though occasionally new sounds may be
added to the local repertoire. This becomes apparent with Albert's
Lyrebirds because they weave the mimicry into a song, 40 or 50 seconds long,
with all the mimicked and other sounds, coming in the same order each time,
and all male Albert's in a particular locality have the same sequential
song.
With Superbs, the mimicry appears to be in random order, but I'm confident
that if anyone took the trouble to tape-record and analyse the mimicry from
all the individuals in one area, it would be found that they all use the
same suite of mimicked sounds.
So imagine that poor Healesville bird. Listening and listening in vain for
a population of singing Lyrebirds. No wonder if, in frustration, he copied
what he could hear: non-lyrebird sounds.
Tony Russell posed this question:
"I believe the mimicry takes place most frequently when a male bird is
displaying on his mound - is this correct ? "
Yes, correct. Norman Robinson (Emu, 96, p. 263) gives a table of a full
day's vocal activity for a Tidbinbilla Superb, derived from a continuous
recording, if anyone is interested.
Norman wrote:
"Approximately half the daylight hours were spent in bouts of vocal
display, of which two and a half hours, or 33% of the day, was spent by the
bird in actual sound production."
Norman doesn't say, and it is possible some vocalisation was made away from
the display mounds, but it would have been a very minor amount. Lyrebirds,
both species, occasionally display on a rock or log, and that song too would
be mainly mimicry, but it doesn't happen often.
Albert's don't have mounds. They display on platforms of trampled vines.
And on a number of occasions I have taped song sessions lasting over an
hour, using a microphone only a metre or so from the platform so that it
would have been immediately apparent if any of the singing had been away
from it.
Now all of that relates to their breeding season song, normally from about
mid-May to early August. Outside the breeding season their singing is
unpredictable as to time, location or content.
I have not listened to Superb Lyrebirds outside the breeding season, but
I've found that Albert's may then mimic a lot of sounds that are not part of
their breeding season song.
Syd
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