Greetings All,
Some bird calls are purposefully difficult to localize and might be
thought of as "ventriloquial." I am thinking in particular of the
aerial predator alarm calls made by many small birds when airborne
danger approaches. These calls are usually a thin high zzeeee that
seems to come from everywhere and nowhere, very useful to alert the
flock without drawing attention to one's location. These aerial
predator alarm calls contrast with the ground-based predator alarm
calls which are coarse, broad-band, and easily localized. The birds
need to know where the cat or perched owl is so they can keep an eye
on it.
I've also noticed that some songbirds sing a territorial song with
similar "ventriloquial" characteristics. The Varied Thrush in the
USA Pacific Northwest sings high, steady or quavering notes while
perched nearly invisible in the old growth forest. This would seem
to have the double benefit of eluding predators while giving rivals
the illusion of omnipresence.
I find it often revealing to study the sound characteristics of a
bird vocalization, these characteristics have usually evolved to the
point that they match the communication need at hand and are worth
trying to understand.
Kevin Colver
On Oct 1, 2007, at 7:59 PM, Syd Curtis wrote:
>
> Would any Naturerecordist care to comment on ventriloquism in birds?
>
> I have encountered occasional references in the literature, but it
> seems to
> me to be a physical impossibility. Am I right?
>
> An accurately focused Telinga should be able to show whether it is
> happening
> or not - given a suitable subject.
>
> I quote below, one example from the literature.
>
> Syd Curtis
> (Brisbane, Australia)
>
> --------------------------
>
> My example is the entry for "Scrub-birds" in the Australian
> Encyclopaedia
> (ten volumes, Angus & Robertson, Australia, 1958).
>
> The entry was written by A.H. Chisholm who was also Editor-in-Chief
> for the
> Encyclopaedia, and was a noted ornithologist of his time. There are
> two
> species of Scrub-birds: the Noisy, Atrichornis clamosus, and the
> Rufous, A.
> rufescens.
>
> Of the Noisy, Chisholm has written "It was discovered by John
> Gilbert in
> November 1842, near Drakesbrook in Western Australia. ... Its voice
> was
> loud, melodious and strongly ventriloquial. No other report was
> made on the
> bird for many years."
>
> And about the Rufous: "This species was named by E. P. Ramsay of
> Sydney who
> in 1866 led an expedition to the Lismore district and obtained
> additional
> specimens. The extraordinary vocal strength, ventriloquism, and
> mimetic
> ability of the bird greatly impressed Ramsay, and so too, did its
> speedy
> movements and its habit of wriggling in mouse-like fashion beneath
> bark and
> other debris."
>
> Chisholm had not encountered the Noisy Scrub-bird. In fact he says
> in that
> article, "The western bird, unfortunately, has not been definitely
> recorded
> since 1889 - this despite many searches - and it may now be
> extinct." (In
> fact it was rediscovered in the 1960's). He certainly was familiar
> with the
> Rufous, but does not appear to be claiming ventriloquialism for it
> from his
> own experience. On the other hand, he was prepared to accept the
> reports of
> others.
>
> (I remain unconvinced.)
>
>
>
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