Pasteurella multocida is a bacterium often called Avian cholera (though it is a different organims than the disease that affects humans). It is estimated that about 15,000 birds have died over the last few weeks in the Great Salt Lake, in Utah. A similar epidemic occurred in 1994, killing 10,000 birds.
There are writeups here at the New York Times and here at the USGS.
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For the longest time, people believed that the world's largest lizard, the Komodo dragon, killed its prey with a dirty mouth.
See pics of this die-off here:
http://greatSaltLakePhotos.com