On Mon, 6 Aug 2001, Matthew Herring wrote:
> Great to read of such an excellent Australian Bustard sighting (6) so far
> south in Victoria. The dramatic loss
> of native grasslands has certainly taken its toll but I think foxes could be
> playing a major role in limiting
> bustard distribution, especially for breeding.
I'm a little sceptical. The Action Plan for Australian Birds nominates
the fox as a threat too but much of the known breeding range for the
Bustard in the HANZAB map is with the range of the fox indicated in
Mammals of Australia.
Admittedly differing fox densities might account for this and the
indicated Bustard breeding range will be incomplete in northern Australia,
but to a first order the two distributions doesn't seem to support this.
You get a more convincing fit if you compare a map of human population
density with Bustard distribution (or declines). HANZAB has lots of
refs for human predation on Bustards and little for fox predation.
Human predation and habitat modification would seem sufficient explanation
for the Bustard's decline - the case against the fox, at least as
expressed in the Action Plan for Australian Birds, seems speculation.
Of course, absence of evidence isn't evidence of absence and perhaps
the fox does have a significant impact on bustards and we don't yet have
the data.
Andrew Taylor
Birding-Aus is on the Web at
www.shc.melb.catholic.edu.au/home/birding/index.html
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