On Thu, Jun 23, 2005 at 11:30:29AM +1000,
wrote:
> There could be thousands more bird species than currently thought -
> which will have major implications for bird conservation, a leading
> bird researcher has found. ...
The paper is linked to David Watson's home page at:
http://www.csu.edu.au/faculty/sciagr/eis/staff/watson.htm
As calls are a topic du jour, here is my mini-review. Its an interesting
paper but I find his thesis that birdwatchers and consequently biologists
are reluctant to accept bird species which can't be diagnosed in the
field and that this leads to lumping of bird species, unconvincing.
He glosses over the extent that diagnosable characters might be more
frequent or better known in birds. The nature and extent of signalling
in birds is clearly different to mammals & herps.
The case of crossbill identification by call is presented as a rare -
but there are many groups of species around the world where birdwatchers
rely on call for separation.
The former conspecific status of New Guinea and Australian logrunners
is presented to illustrate the difficulty of diagnosing species in the
field but the plumage differences described in Leo Joseph's Emu paper
are not trivial. They seem easy to separate than (for example) many
seabirds - taxa accepted by birdwatchers. Note also their calls are
said to be quite different.
Judging by this list, rather than being suspicious of species which are
difficult to separate in the field , many skilled birdwatchers apparently
relish the challenge.
I'm not sure of the relevance of the discussion of syringeal morphology
as an example of a character provided by internal morphology and hence
not available for field diagnosis. Surely readily distinguishable
differences in syringeal morphology will be reflected in call characters
- a diagnosable character.
The example of the 2 genetically divergent populations of New Guinea
logrunners which are said to be indistinguishable in the hand doesn't
mention call characteristics - maybe these aren't known - but as they as
passerines from a poor visual environment, it makes for an empty example.
Andrew
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