Should Blue-billed Duck be listed as at least Near Threatened?

[Lawrie Conole <>]

m("npws.nsw.gov.au","David.Geering");"> wrote:
>  On this forum Lawrie Conole highlights the number of Blue-billed
> Duck currently (or at least in late 2002) at Werribee.  He also suggests
> that having 10 000 Blue-billed Duck (greater than the current population
> estimate for eastern Australia) all at one location is dreadful risk management
> by the taxon in question. 

I was of course saying that with my tongue firmly planted in my cheek!

Stephen Garnett pointed out too that the maximum estimate at Werribee in
late 2002 was 12,000 Blue-billed Ducks.  This is a gobsmacking
number, and I think (given that it exceeds by circa 2,000 the previous
estimate for the entire eastern Australian population) that maybe my flippant
comment about risk management was not so silly after all.

> A very good point of course - all your eggs in one basket
> and all that.  What are the risks for these Blue-billed Duck?  A huge hailstorm
> perhaps?  Thinking more laterally however, is there any risk of the ducks
> picking something up from this water (partially or completely treated as
> the case might be) that might have an adverse impact on the population?  I
> guess the potential for something being passed from primates to ducks is
> pretty remote but is it possible?  Sewage treatment plants are great places
> to see ducks but are they great places for ducks? 

There are no recorded instances that I'm aware of  for any kind of toxic
spike knocking off large numbers of birds at Werribee, but this strikes me
as a possibility.  Maybe the dilution factor from Melbourne's enormous discharge
of wastewater renders this risk negligible?  Many of the ponds were mint
green earlier this year with blue-green algae, but birds were merrily surfing
about in that too.

> Personally I have no idea.  Anyone out there have any expertise
> in this area? 

I'm with you David - please forward all speculation (idle or otherwise) for
our consideration or edification.

L.

-- 
=================================
Lawrie Conole
Senior Ecologist
Ornithology & Terrestrial Ecology
 
Ecology Australia Pty. Ltd.
Flora and Fauna Consultants
88B Station Street
FAIRFIELD VIC 3078 Australia
E-mail: m("ecologyaustralia.com.au","lconole");">
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