Re: Cannon Netting

Subject: Re: Cannon Netting
Date: Fri, 23 Jun 1995 21:53:24 -0400 (EDT)
I was formerly involved in both the cannon-netting of waders and the 
mist-netting which preceded it. My impression was that while the 
cannon-netting did kill some birds, the majority left in pretty good shape. 
I certainly can't say the same of the mist-netting!

The problem was that as the night wore on, more people would fall asleep, 
so there were not enough working on the simple problem of getting the birds 
out of the nets. And the nets sagged and got loose. We didn't even have 
time to close up the nets, let alone retension them! As a consequence, many 
birds got badly tangled and suffered injuries, especially to the elbow 
area. This was worst with the smallest birds, like Red-necked Stints. 
Hundreds of birds were affected so badly that they couldn't fly the next 
morning. I hate to think what the ultimate mortality was, although the 
immediate mortality was very low.

My feeling was that this kind of mist-netting, driven by a desire to catch 
as many birds as possible, was unacceptably intrusive on the birds being 
caught. But the APPARENT mortality was low. And with a few modifications to 
the catching protocol, the harm being done could have been greatly reduced, 
at the cost of catching somewhat less birds. But it wasn't.

So while the deaths due to cannon-netting might be spectacular, the process 
may still be much less intrusive than some alternatives. It is probably 
better to kill 2% than to maim 60%. I'm not opposed to wader banding, so 
long as there is honest appraisal of its impact and modification of 
techniques where necessary. Presumably this happens to some degree - I 
would certainly hope that the disastrous mortalities seen in the northwest 
and around Sydney will not be repeated, because techniques have been 
improved as a result of those incidents.

Rory O'Brien wrote:

>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.

Can he justify these claims? While certain types of information require the 
marking of individuals (eg determining the age structure of a population's 
mortality, or migration routes), it seems to me that in the case of waders, 
which are very easily observed, visual counts should be FAR more effective 
for determining overall populations and their long term trends. And the 
percentage of juvenals in a population could be determined by visual counts 
MUCH more effectively than by banding.

>(live retraps) is up to 25% in some catches.  This sort of recovery rate 
>is EXTREMELY high and provides invaluable data about population trends, 

What is that data and how has it been used?

Chris Corben
PO Box 128
Olema CA 94950


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