Global Environment.com |
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Saturday, 11 January,
2003.
Rare birds fall prey to botulism
Dangerously high numbers of one of the world's rarest and most spectacular
birds have died from disease in the last month.
An outbreak of avian botulism has killed 71 black-faced spoonbills
in Taiwan since 9 December 2002.
This is more than 7% of the world population of 969 birds, according
to BirdLife International.
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Rare birds fall prey to botulism |
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Red alert over rare species |
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The
outbreak follows a spell of unusually warm winter weather, and ornithologists
think similar incidents could become common.
Avian botulism is caused by a water-soluble toxin produced by the bacterium
Clostridium botulinum (in this case, type C). It is a potent neurotoxin.
Black-faced spoonbills breed on small islands off the west coast of
the Korean peninsula and China.
Their main wintering wetland sites are in Taiwan, Hong Kong, Vietnam,
China, Japan, Macao and South Korea. |
There are fewer
than 1,000 black-faced
spoonbills worldwide
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Rapid
help
A census conducted in January 2002 concluded the 969 birds found were
the entire global population.
The first dead birds were reported by the Wild Bird Federation of Taiwan
(WBFT) on 9 December, and analysis showed avian botulism was the cause.
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They were found in Taiwan's Tseng-wen estuary, the most important wintering
site in the world for the birds with more than 70% of the global population.
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WBFT, the Taiwan partner of Birdlife,
and its local branch, the Wild Bird Society of Tainan, set up an emergency
rescue team to try to save some of the infected birds.
The last dead birds were reported on 4 January, and 17 others have recovered
so far.
The Taiwanese authorities and WBFT are working to minimise any recurrence
of the disease at Tseng-wen by changing the way organic pollution is
controlled.
They are also stockpiling type C botulism antiserum, which was used
to help five sick spoonbills back to health.
Professor Chien-chung Cheng, the president of WBFT, said the loss of
more than 7% of the world's black-faced spoonbills was "a significant
blow to this already endangered species".
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Pollution link
BirdLife says: "The higher than usual winter temperatures that
appear to have triggered the outbreak seem to be consistent with anticipated
climate change patterns.
"BirdLife fears more incidents of this nature may be expected to
occur in future."
The entire outbreak included three distinct waves of the disease, each
following a sudden temperature drop.
Scientists think the earlier warm temperatures caused fishponds around
the estuary to become eutrophic, a process in which the population of
algae would have increased rapidly.
The colder weather could have caused a mass algal die-off, with the
decomposing algae depleting oxygen levels in the water.
Hopes dashed
This would have killed fish and shrimps, providing ideal conditions
for the bacteria to multiply rapidly.
The birds' endangered status means ornithologists think they face a
very high risk of extinction in the wild in the near future.
But until 2001 they were classified by IUCN, the World Conservation
Union, as "critically endangered", facing an "extremely
high" extinction risk.
Their prospects, ironically, had actually improved with the establishment
of a protected area in the Tseng-wen estuary in November 2002.
source: http://news.bbc.co.uk |
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