Hi everyone
I think that Bob is on the right track. If botulism is involved, it is
caused by
a bacterium Clostridium botulinum which is anaerobic, i.e. it can't survive and
multiply in air/oxygen. Therefore in nature it is often found at the edges
of water bodies
with much rotting vegetation which depletes the oxygen in the water and mud.
C. botulinum is very widespread but only causes a problem when the
environmental
conditions are right for it to multiply.
The bacterium produces a neurotoxin that seems to affect the muscles of neck
and wings first, preventing flight and causing the head to drop, and later
death.
These signs are fairly diagnostic.
If other species were not affected they may have been feeding in different
areas or
different depths of water.
Some species (like raptors) seem to have greater resistance to the toxin
and can
feed on carcasses without becoming affected themselves., but I think that most
waterfowl are quite susceptible.
It is very widespread in North America, causing thousands of deaths each
year.
There are far fewer documented reports of it from Australia (I published on an
outbreak of it in the Brisbane Valley in the 1970's) but I suspect that it is
widespread but often overlooked.
Pete
At 07:21 PM 1/12/2005 +1000, you wrote:
G'day all,
It could be that is that the Pink-eared Ducks have a different feeding
regime to other waterfowl ?
They feed by filtering their food from the surface of the water whereas
other species dabble from below the surface ?
So, if a poison of some sort is floating on the water they would be a goner !
I am always amused that our Pink-eared frequently circle around closely
behind each other in twos or threes with their beaks almost up the
preceding duck's bum.
Regards from
Bob Forsyth
Mount Isa, NW Qld.
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