I should state from the outset that I am a
student of David's at CSU and was at the time that this article was prepared.
I think that the broad thrust of this paper is
pretty robust. One may argue about details but David has solid figures
there. Notwithstanding Andrew's point about signalling differences between
mammals, reptiles and birds, you can't argue with the many other obvious
differences illustrated between the diagnostic methods which are in common use
among other Classes versus those in use for Aves and to question why
this is so is healthy. Of course differences in Classes will mean that slight
biases in diagnosis will take place but unles there is something wrong with
David's methodology, there are clearly substantial imbalances in
diagnosis which cannot be accounted for by these differences
alone.
In many respects David's paper is correct
about "bird watchers". It bears consideration that many people wont go near
waders or pelagic species because of percieved difficulties in forming accurate
species diagnosis on the basis of appearance. Many are terrified of "little
brown birds". The numbers of specialists in various areas who will relish the
difficulties in diagnosing various hard to split groups of species accounts for
a very small number of birdwatchers. Therefore your point Andrew,
which contests whether lumping takes place due to the reluctance to accept
new species is not convincing to me.
Given that birds hear sounds up to 200 cycles per
second, versus the roughly 20 cycles per second of humans, it is a fact that
variances in syringeal morphology may not produce song which is distinctive
enough to the human ear for accurate diagnosis and therefore the point that
syringeal analysis may be of importance is very well made. There may be many
species out there speaking entirely different languages and without further
study of vocalisations, we may not be aware of it. The case raised with Crossbills (rare or
not) illustrates just this point very well but also
that behavioural differences as much as call are important. In this case
diet: each species preferring a distinctive species of pine upon which to
feed and David is clear on this point. He was also alluding to the fact that
birdwatchers can play an important part in helping to gather information which
will contribute to our knowledge on these matters. This case also
demonstrates the fundamental importance of developing realistic and
practical measures for understanding diversity as, with the loss or reduction of
a specific pine, the loss of a hitherto unrecognised species of bird would also
tragically occur.
The currently adopted Biological Species Concept
(not necessarily included in David's discussion) does not give us the tools
to properly understand the true diversity of birds and nor does a process
weighted in favour of phenotypic analysis of species adequately serve
scientists, birders or the birds themselves. David's call for a review of the
later processes is timely.
Happy birding
Ricki
Broome WA
