Does anything useful come out of cannon netting and does it help in their
conservation??? In my experience the answer is YES - very definitely.
Wader banding gives the INFORMATION you quote on the size of populations
(along with counts of course), it provides info on the structure of the
populations (% juveniles etc) and the LONG TERM trends in populations.
All of this information is essential for their conservation. For
instance, even common waders (E.g. Red-necked Stint) appear to be in
decline. Such information has probably influenced ANCA in their
decisions to now employ people such as Doug Watkins to work with the
Asian Wetland Bureau (AWB) on wader conservation throughout the flyway.
This appointment (for at least 1 year from now) will be of great benefit
to waders who are far more at risk on their migration through Asia than
they ever could be through waderbanding (figures such as 50,000 (or was
it 500,000?) Oriental Pratincoles being caught for food on just ONE
island in the flyway spring to mind).
In case anyone is interested the mortality rate from cannon netting is
generally around 0.5 - 2 %, from memory. I also have memories of *VERY*
nasty incidents (e.g. oystercatchers being cut in half by cannon-nets)
and these are obviously difficult to deal with and almost impossible to
justify. However although they tend to be dramatic and memorable, and to
be the first thing that comes to mind about cannon netting, there is much
more to it. For instance, the number of waders banded each year in
Victoria alone is well over 2000, usually 5000, and the recovery rate
(live retraps) is up to 25% in some catches. This sort of recovery rate
is EXTREMELY high and provides invaluable data about population trends,
etc - more to the point, for each bird banded there is a high probability
that it will provide useful information. This contrasts with some
species of bush birds, which usually disappear without trace after
banding.
Just one other point for the record (although I wasn't there) the
Long-billed Dowitcher was not recognised as such until it was netted by
the VWSG, and it was identified in the field and photos taken.
Subsequently these photos were brought into the RAOU and discussed by
resident and non-resident experts (e.g. Bob Swindley, Kevin Bartram,
David Eades etc etc)) who after some debate agreed it is most likely to
be a long billed. Bill length was in the ranges of both spp, the wing
and tarsus very close to the upper limit for short billed. The tail had
very narrow bands of white in the centre but 50/50 on the outer tail
feathers, and the grey on the breast had no visible spotting but did
break up a little in the lower parts. The bird was in winter plumage and
had no moult on the wing. The consensus was ~90% probability that it is
a long billed.
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