>Could a system such as say, an expert go into a defined area and survey
the
area to find out the relative proportions of each taxa. While at the same
time a couple of people simply stratify the area and go through and count
numbers of parakeets? I know the problems of error here are going to be
very large!!
Seems to me that this might be the best, or least worst, method. It is
similar to what we had to do with aerial surveys of Long-billed Corellas (I
know, they are extremely common where we did our survey). Sulphur-crested
Cockatoos occur in the same area. Based on extensive ground survey work,
we knew the proportions of the two species. From the air, we only had to
count white cockatoos (couldn't always distinguish between the species from
the air), and then apply a correction factor based on our observed
proportions from the ground surveys.
In your case, you would need to know by how much and over what period the
relative proportions of the two species vary, within defined areas. If the
variation is not large over the kind of time required for the non-expert
observers to count numbers of parakeets, then this system might be
feasible. I can't think of a better one.
Hope this helps.
Cheers
Ian
=======================================
Ian Temby
Wildlife Damage Control Officer
Secretary/Treasurer, BIRDS Australia Parrot Association
Flora & Fauna Program
Department of Natural Resources and Environment
4/250 Victoria Parade
EAST MELBOURNE VIC 3002
AUSTRALIA
Phone 613 9412 4429
Fax 613 9412 4586
E-mail
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