Cannon Netting

To: Kym Bennet <>
Subject: Cannon Netting
Date: Wed, 7 Mar 2001 09:48:40 +0800
Kym Bennet <> wrote :
>We have obtained sufficient knowledge now to allow
>the phasing out of this process in favor of more passive
>field observing techniques to further expand the
>information base.  With the use of advanced technology
>in video, photography, optics, infrared, night vision, radar,
>sound recording and other techniques combined with
>mobility options that were never previously feasible, we
>should be able to obtain results which are adequate for
>most study purposes.

People do not cannon net for the fun of it.  You do not get 70 or 80 people
from around the world to spend 2 to 3 months in the north west of Australia
just to cannon net waders for no beneficial purpose.  I have participated
as an assistant in two banding expeditions to Broome and the north west and
I have seen first hand the information that is being gained.  These
volunteers participate at their own cost, and in their own time off work.
They participate because they can see first hand the benefits that are
being gained from each expedition.  Many of them return for future
expeditions.  You don't camp next to the mangroves at the Port Hedland salt
works in March in 40+ degrees with clouds of mosquitoes and sand flies for
the fun of it!!

I have seen how they can determine the age of some species by weight or
wing moult or other characteristics which cannot be determined by means
other than having the bird in the hand.  This information isn't gained for
reasons of pure science.  It is used to estimate and monitor populations,
the breeding success each year, whether birds of different ages have other
different characteristics, etc.  This information is important for the
ongoing protection of the birds.

I have seen the evidence from retraps that birds generally return to the
same site over the years.  I have seen the evidence from retrapping a bird
several times over two months of the information gained on changes in
weight, moult, etc which allows estimates to be made of the feeding

I have seen overseas participants from England, Canada, USA, South Africa,
Netherlands, Russia, Indonesia, Thailand, Vietnam, Korea, Japan, etc learn
this information and then be able to make a difference in their countries
with this knowledge and experience.

Cannon netting is not the be all and end all.  It is used in conjunction
with other study methods.  I have seen these participants initiate studies
on the biomass of the mud flats to determine why these areas support such
large numbers of waders.  I have seen them study individual species to see
how each species feeds, and differences between sexes in feeding.  I have
seen them use infrared vision at night to study if there are differences in
feeding techniques.  I have seen them systematically count the waders as
they migrate and to monitor them by radar where possible.

Each expedition to the north west has a very well set out list of specific
objectives documented in the information notes.  Some of these questions
remain unanswered, but there are always other results and learnings outside
of the initial objectives.  They use cannon netting because these questions
are considered to be important and because it is the most effective means
of gathering the data needed.

I have read of the satellite tracking of Eastern Curlews in Queensland and
Victoria.  This showed that migration is not simple and that there is a
large amount of knowledge still to be gained.  Birds don't just take off
and head north.  They back track.  They stay at unexpected places.  They
wait for bad weather to pass.  They do all sorts of unexpected things.

I don't believe that we know enough about the waders yet to eliminate the
need for cannon netting.  I worry that Roebuck Bay and 80 Mile Beach have
not been designated as marine parks as has been previously proposed.  I see
the number of waders at Alfred Cove in Perth seemingly dwindle over the
years and I don't know why.  I don't know where they come from.  I don't
know if perhaps they are feeding somewhere else, or there really are fewer
birds.  I don't know where the large number of Red-necked Stints, Curlew
Sandpipers, Sharp-tailed Sandpipers come from each year to feed for a month
or two at Lake McLarty in the south west of WA.  I don't know where they
went this year because the water level was too high.  I don't know why
Greater Sand Plovers are more common than Lesser Sand Plovers in Broome and
in the south west, but that Lesser Sand Plovers are more common in the
Pilbara and Gascoyne coasts in between.  I don't know why there were large
flocks of Red-necked Stints and Ruddy Turnstones in breeding plumage on
Adele Island about 400km or so north of Broome when I was there in mid May
about 1994 and why did one have a Victorian rather than WA leg flag.  Were
they migrating from the south east of Australia?  And why were they on this
island and not on the mudflats in Broome where they have finished migrating
usually by the end of April?

Other methods can be used, and are used when necessary.  Mist netting of
waders can only be done at nights, and usually when there is not much
moonlight.  It often needs to be done when the birds are feeding.  Cannon
netting is done at high tide when birds are roosting.  So there is much
less disruption to the birds.

On the subject of mortality, I have observed maybe 3,000 to 5,000 birds
banded.  I have seen less than 10 birds killed and maybe another 10 to 20
significantly injured.  I probably missed observing about the same number.
This is distressing and regrettable.  However, I argue that studies such as
these will help to reduce the large scale catching of waders in Asia for
food at their migration stopovers, and to help to conserve their important
feeding sites.

It is possible that the need to carry out large expeditions will become
less important sometime in the future as more and more questions are
answered about the birds.  But there will always be an ongoing benefit from
smaller scale cannon netting to monitor the populations of the waders by
determining the age distribution and breeding success each year.

Kym, I assure you that 60 Minutes is far far far more likely to do a
positive story on the results of the wader studies, than the negative story
that you suggest.  Take for example the story of Clive Minton and the
Banded Stilts of Lake Eyre last year.  Cannon netting was not involved in
this story, but it shows that 60 Minutes are prepared to do positive
stories.  These are dedicated volunteers doing useful research that
benefits the conservation of these species.  Clive Minton well deserved his
award in this year's Australian honours list.

I am only an observer and an occasional assistant.  This is why I feel that
I can comment freely on this issue where others that are more directly
involved would feel constrained.  I do not have a vested interest in the
continuation of cannon netting.  I could go on about the benefits that have
been gained from cannon netting, and can still be gained in the future.
However, I suggest that you go to your state or university library and look
for journals such as The Stilt or The Tattler, or other journals where the
results of these studies are published.  You can then judge whether cannon
netting is beneficial, and whether there is still an ongoing usefulness and

For those that wish that this topic would die I request their understanding
and patience.  Because this mailing list is archived I believe that it is
very important to refute uninformed and unsupported statements, and to
promote the reasons and benefits of cannon netting.  If the counter
argument is not made then this myth (e.g. large mortality) will become
accepted fact.  It is a small sacrifice to hit the delete key if you have
no interest in the topic, a sacrifice that I regularly make for some other
topics that don't interest me.

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