At 13:09 24/09/98 +1000, you wrote:
>
>The question regarding differential predation of colour-dyed waders is an
>interesting one. The gut feeling is that these birds may well be subject
>to higher predation. I was wondering how best to test this as birds would
>just drop out of the population with little, if any, direct evidence for
>the cause or, indeed, any indication that they had perished at all.
>
>Hugo then suggests that an analysis of recapture rates might provide the
>answer. Indeed it may and I would suggest that the AWSG should make it a
>priority to have a look at the data to address the issue. It is always
>reassuring to know that what you are doing is proving important information
>but also that it is not unduly affecting the animals chances of survival.
>
>
>David Geering
>
>
I agree with David that this is something that should be looked at but
I'd disagree with Hugo that this can be done merely by looking at
survival rates of the "yellow" birds vs. unmarked birds from a year's banding.
(if I've understood your suggestion correctly, Hugo?) because a range
of factors other than the yellow dye could influence the survival of
birds captured at different times and different places.
I'd suggest that at a major banding operation, birds be allocated randomly
to dye and no-dye groups and then the survival of birds in these two groups
be followed. Sorry if I seem to be pedantic but I think this is the way to go.
Peter
Dr Peter Woodall email =
Division of Vet Pathology & Anatomy
School of Veterinary Science & An. Prod. Phone = +61 7 3365 2300
The University of Queensland Fax = +61 7 3365 1355
Brisbane, Qld, Australia 4072 WWW = http://www.uq.edu.au/~anpwooda
"hamba phezulu" (= "go higher" in isiZulu)
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