AVIAN CHOLERA - USA: (OREGON, CALIFORNIA)
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Date: Fri 30 Mar 2012
Source: Standard-Examiner, Redding Record Searchlight report [edited] <http://www.standard.net/stories/2012/03/30/more-10000-waterfowl-die-drought-related-outbreak>
More than 10 000 waterfowl die in drought-related outbreak
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At least 10 000 migrating snow geese and other waterfowl have died this spring [2012] at drought-plagued Lower Klamath and Tule Lake national wildlife refuges along the Oregon border with California.
Biologists are calling the avian cholera outbreak one of the biggest drought-related die-offs in the refuges' more than 100-year history.
"We're going to estimate about 15 000 dead by the end of the outbreak," refuge manager Ron Cole said.
In an area that's increasingly stricken by drought, Cole said something needs to be done to protect the birds, and he warns of a more and larger die-offs in the years to come if the refuges don't get increased water allocations as promised in a settlement that also includes plans to tear down 4 dams on the Klamath River.
Cole said cholera kills ducks and geese nearly every year, as the migrating birds congregate on the refuges, which they use as a feeding and resting point on their journey north.
But Cole said this year [2012] is especially bad since the refuges'
marshes have been scaled back to half their normal size by of a lack of water.
Since early March [2012], 2 million migrating birds have been loafing and feeding in dense numbers on what open water was left, easily spreading the disease among the densely packed flocks.
The US Bureau of Reclamation cut off water to the refuge on 2 Dec [2011] due to low snowpack levels and expected low inflows to Upper Klamath Lake, said Kevin Moore, a bureau spokesman.
He said the bureau has to maintain water levels in Upper Klamath Lake under agreements to protect the endangered lost river and short-nosed suckers [an endangered fish, _Chasmistes brevirostris_].
In addition to maintaining the level of Upper Klamath for the suckers, the bureau also has to deliver water to area farmers who have contracts with the bureau.
At the same time, water managers have to make sure they keep enough water in the Klamath River to support the endangered coho salmon.
Cole said the majority of the dead birds are snow and Ross's geese.
But a larger than normal flight of northern pintail ducks also suffered die-offs. He said refuge employees and volunteers have picked up about 4000 dead birds to help stop the disease from spreading even more. Many others became food for bald eagles and other raptors that dine on the birds. They don't seem to be susceptible to the disease, Cole said.
While it might mean extra food for birds of prey, Cole said the die-off could be a harbinger of things to come at the refuge complex if it doesn't soon get water rights.
John DeVoe, executive director of WaterWatch of Oregon, blamed the dead waterfowl on politics. "These refuges are too important to become a sacrifice zone for failed state and federal policies," DeVoe said.
"Ensuring Tule Lake and Lower Klamath national wildlife refuges have an adequate supply of water, and that commercial agribusiness doesn't displace wetland habitat on these refuges, are critical steps to protecting the Pacific coast's migratory waterfowl populations as well as restoring the Klamath's struggling native fish."
[Byline: Damon Arthur, Ryan Sabalow]
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ProMED-mail from HealthMap alerts
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[It is not stated whether the diagnosis was confirmed. Avian cholera is a disease caused by the bacteria _Pasteurella multocida_. Bacteria released into the environment by dead and dying birds, or by birds carrying the disease, can subsequently infect healthy birds. In addition, dense concentrations of waterfowl can enhance disease transmission to susceptible birds. As a result, avian cholera can spread quickly through a wetland, killing thousands of birds in a single outbreak. Pickup and disposal of carcasses has become the primary management strategy to reduce transmission to susceptible birds.
Avian cholera outbreaks tend to occur every year in some wetlands.
Although it is expected at certain levels, anomalies in these levels should raise concern. The relationship between avian cholera outbreaks and drought is inconsistent. Some researchers found a positive correlation with precipitations. Others suggest that absence of rain lead to high concentration of waterfowl, leading to unusual high mortality. The influence of water shortage on these episodes should be investigated in detail.
Images of snow goose (_Chen caerulescens_), Ross's goose (_Anser rossii_), and northern pintail (_Anas acuta_), can be respectively found at <http://upload.wikimedia.org/wikipedia/commons/7/7a/Chen_caerulescens_32398.JPG>;
<http://upload.wikimedia.org/wikipedia/commons/a/ac/Anser_rossii_-California%2C_USA-8a.jpg>;
and
<http://en.wikipedia.org/wiki/File:Northern_Pintails_(Male_%26_Female)_I_IMG_0911.jpg>.
A map of the affected area can be seen at <http://healthmap.org/r/273e>. - Mod.PMB]
[see also:
2008
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Avian cholera - USA: (UT) (02) 20120106.1001760 Avian cholera - USA: (UT) 20080104.0041
2007
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Avian cholera - Canada (NL) (03): NOT 20070414.1248 Avian cholera - Canada (NL) (02): NOT 20070410.1216 Avian cholera - Canada (NL) 20070408.1178
2006
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Avian cholera - Canada (NU) (02) 20061031.3119 Avian cholera - Canada (NU) 20060725.2051 Avian cholera - USA (WI): corr. 20060501.1263 Avian cholera - USA (WI) 20060430.1258 Avian cholera, snow geese - USA (AR): susp. 20060113.0127] .............................................ll/sb/pmb/mj/lm
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