Max,
Not really so. The birds studied by Mario Cohn-Haft belong to the Tyrannidae
family, which are part of the Suboscine passerines, which are almost
confined to the New World. The only Old World birds belonging here are the
pittas, broadbills, asities and New Zealand wrens. Recent studies have shown
that songs among the suboscines are mainly innate, and thus rather
invariable. That's also why the study of vocalizations in this group can
furnish valuable information concerning their taxonomy.
In the other passerines, however, to which the families you mention belong,
the learning process plays an important role in vocalizations, and it is
thus not hard to understand that they can fairly easily change in time, and
from one area to another. In fact, 'dialects' are common in many
well-studied birds, even within the same subspecies. These differences do
not normally have taxonomic consequences.
Paul Van Gasse
Kruibeke, Belgium
-----Oorspronkelijk bericht-----
Van:
Max O'Sullivan
Verzonden: donderdag 8 februari 2001 6:37
Aan: birding-aus
Onderwerp: [BIRDING-AUS] Re: Vocal classification of species
In a recent American publication, I read the following that may be of
interest to some readers:
"Mario Cohn-Haft (a Brazilian ornithologist) was recently awarded a Ph.D. in
zoology from Louisiana State University for his research on Hemitriccus, an
obscure genus of small flycatchers known as tody-tyrants. Mario showed that
vocally recognizable populations of this bird are genetically distinct.
He found that vocal classification is a better way of recognising genetic
differences in these birds than the physical appearance-based subspecies
classifications found in most field guides.
According to Mario's research, distinct vocal types probably represent good
biological species that will need to be split. For example, what we know as
the White-eyed Tody-Tyrant is actually three distinct species. What's more,
some of these very similar and hard-to-differentiate species (even as
currently classified without splitting) differ from one another genetically
as much as some genera of North American bird species differ from one
another, suggesting that they are extremely old."
Does this point to similar possibilities in some of our own bird populations
in which the call is noticeably different in different parts of the country?
Cicadabirds and Mistletoebirds, for example, have noticeable call variations
that have been pointed out to me on numerous occasions. So now, we not only
have to record all subspecies in case of future splits but also have to take
note of vocalisation in birds that might look the same but sound different
in case they are different species!
Cheers
Max O'Sullivan
Brisbane
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