Hi Chris,
A response from the AWHN:
We have a Fact Sheet on Botulism which provides a bit of information -
http://www.wildlifehealth.org.au/AWHN_Admin/ManageWebsite/FactSheets/UploadedFiles/118/Botulism%20-%20Diagnosing%20(Birds)%2016%20Jan%202008%20(1.0).pdf
.
I suspect the epidemiology of botulism is complex and may present differently
dependant on environmental factors and bird feeding patterns. However based on
some of the literature and certainly not a comprehensive review, the grebes may
not be feeding on substrate / fish affected by the toxin. Based on the UGSG
NWHC Chapter in Avian disease on Botulism -
http://www.nwhc.usgs.gov/publications/field_manual/chapter_38.pdf
- filter feeders (ducks) seem to be at highest risk of type C. However Canada
has reported type E in species such as grebes via feeding on fish (see:
http://www.ccwhc.ca/wildlife_health_topics/botulism/botulisme_org.php#bird
) Plus the attached may be of interest.
It sounds as if this has previously been reported and the event investigated.
The person to report to would be the Wildlife Coordinator in the Northern
Territory, Cathy Shilton. She is a veterinary pathologist and may have much
better knowledge regarding why certain species are affected too.
Cathy's contact details are:
Dept of Business, Industry and Resource Development Berrimah Vet Laboratories
GPO Box 3000
Darwin, NT 0801
W: 08 8999 2122
For the most recent List of Wildlife Coordinator's Contact Details for
reporting wildlife mortality events follow the link:
http://www.wildlifehealth.org.au/AWHN/ProgramsProjects/Programs.aspx
and click on Wildlife coordinators (General surveillance).
http://www.wildlifehealth.org.au/AWHN/ProgramsProjects/Programs.aspx?id=9
There's also a paper I can send you if you want it:
Rocke, T. E. 2006. The global importance of avian botulism. Waterbirds around
the world. Eds. G.C. Boere, C.A. Galbraith & D.A. Stroud.
The Stationery Office, Edinburgh, UK. pp. 422-426.
Cheers,
James
James O'Connor | Head of Research
BirdLife Australia, Suite 2-05, 60 Leicester St, Carlton VIC 3053
Tel: (+61 3) 9347 0757 | Fax: (+61 3) 9347 9323
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-----Original Message-----
From:
On Behalf Of Carl Clifford
Sent: Wednesday, 8 February 2012 1:52 PM
To: Chris Watson
Cc:
Subject: Botulism poisoning in waterfowl
Chris,
Though Grebes are divers, they feed on crustaceans, fish etc and tend
not to go poking around in the mud at the bottom of the ponds. Diving
ducks tend to ferret around in the bottom mud and would be more likely
to get into the anaerobic layers.
Cheers,
Carl Clifford
On 08/02/2012, at 1:28 PM, Chris Watson wrote:
G'day all,
A bit of a technical question. I've been monitoring the mortality rate
of a few species at Alice Springs Sewage Ponds after a spike in
botulism poisoning last year.
I'm not a biologist, but what I've learnt is that "c" type Clostridium
botulinum bacteria reside and breed in anaerobic muds at the bottom of
the ponds. When we get the warmer weather the amount of bacteria
increases and bottom feeding birds (swans, diving ducks) can stir it
up and ingest it, resulting in the increased mortality that we witness.
At the moment we are seeing a greater number of dead and moribund
birds around the ponds (mostly Black Swan, Hardhead, and the
occasional Grey Teal).
My question is this; why are the aforementioned species affected but
the grebes (Australasian and Hoary-headed) which are accomplished
divers have not been observed to be affected to this point. In 18
months, I have not found a single grebe carcass or seen any grebes
that seem effected by botulinum toxicity. I am at the ponds at least
twice a week so have a very good idea of the changes in populations
and movements there. We have a fairly stable population of between 80
and 120 grebes, and I'm surprised that they never seem to be affected
by this toxin which always seems to take out quite a few swans and
ducks (and the odd stilt and lapwing) each summer. I can only imagine
that there is some difference in their feeding technique or the
physiology of their digestive tract which keeps them safe from it.
Can anyone enlighten me?
Cheers,
Chris Watson
Alice Springs
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