On Thu, 30 Mar 1995, Harriet Whitehead wrote:

> I appreciate Teresa's posting on the most probable way to program
> a computer for bird-song recognition - in terms of "voice quality" rather
> than the range of possible phrases. I notice in my own birding that the
> singer's voice quality is often the thing that first triggers my
> recognition well before I've 'computed' whether the phrase or song fits
> my song knowledge. One reason I ask friends who are new to birding and
> dismayed at the idea of identifying songs, "Well, how long did it take
> you to learn all your (human) friends' voices on the telephone?"


I have to voice some scepticism about the usefulness of voice quality. I
have also had the experience of knowing a bird's calls so well that
without even consciously noting the pattern of the song, my mind
immediately told me "Robin," or "Blackburnian Warbler." The recognition
was so instantaneous, and worked so consistently, even for unfamiliar
variants of the species calls, that I assumed I had learned the voice
qualities of the species involved. Now I'm not so sure.

The experience that changed my outlook was birding at night. I did my
master's research on the vocalizations of the Northern Saw-whet Owl, and
even before that intensive year of fieldwork, I spent a lot of time
chasing the lesser known owls at night in New England. Since most of the
calls of the Saw-whet Owl and the Long-eared Owl, and some of the calls of
the Barred and Eastern Screech-owl were unavailable on tape and
undescribed in field guides, I was left to figure out who was who on my
own. Even after several years, and hundreds of encounters with Saw-whets
and Screech Owls, I never recognized a call that was genuinely new to me,
not at first. In fact, I seldom could rule out the possibility that the
call was coming from an amphibian or mammal, or an insect, except by
locating the source. (Of course, if the caller flew, that helped). I
have mistaken one owl species for another so often that I just don't jump
to conclusions anymore. There is nothing unique about the voice
characteristics of any owl species, *until* you have heard a particular
call often enough to know it. I believe the same is true of all birds.

Let me paraphrase Kenn Kaufman (always good for a few cheap points) in the
field guide to advanced birding, on judging size in birds. Kaufman says
(from memory, so very approximate), that he felt, after years of birding,
that he could judge the size of birds in the field quite accurately. He
would look at a shorebird, and classify it as about seven inches long - a
largish peep - and he would nearly always be right if he eventually ID'd
the bird and checked its size in a field guide. All his confidence in his
ability was shaken permanently, however, the first time he birded on a
different continent. He would get a good look at an unfamiliar species,
make an estimate of size, and find out he was consistently wrong, and by
wide margins. He concluded that what he had really been doing back in the
US was *not* judging the bird's size directly, as he first had thought.
Instead, he was unconsciously figuring out the likely identity of the
bird, and his brain was supplying the size that he knew (from reading)
that that bird was supposed to be. That is, he thought he was using the
size of the bird to help him identify the species, when what he was really
doing was using his identification of the bird to help him judge the
size.

I think that when we bird by ear and recognize the "voice qualities" of
birds, we are doing the same thing that Kaufman did when he judged the
size of North American birds. I sincerely believe that I could play any
birder (or any computer) a call that was not in his/her/it's memory bank
already, and no matter how well the birder knew the rest of the species
repertoire, he/she/it would be clueless on the new one.

Of course, my opinion is worth exactly the same as anyone else's :)
I have some obscure calls of common passerines on tape - anyone want to
call my bluff? My owl work has also made me think it would be fun to test
naive passerine (i.e. prey) birds to see if they could recognize the voice
characteristics of an unfamiliar owl as a predator. Surely that would be
adaptive, and owl sounds are pretty recognizable as owls even to us, to
whom it doesn't really matter, right?... I've never done the test,
though.

Chris Hill
Seattle, WA
cehill at u.washington.edu