October 1, 1996, the National Wildlife Health Center ceased differentiating
its mortality reports by geographic region. The mortality table
accompanying this report, therefore, lists all events by state in
36 reports this quarter. Avian cholera was the cause of mortality
at multiple sites in Nebraska and California. Waterfowl populations
migrating through Nebraska's Rainwater Basin this spring peaked
at 3-4 million birds. Mortality was first observed in the beginning
of March, and state wildlife and U.S. Fish and Wildlife personnel
collected 3,428 birds, primarily snow geese with other goose and
dabbling duck species. Merced NWR, California also reported high
mortality due to avian cholera this quarter. Over 4,000 waterfowl,
primarily coots, died with a peak of 300-400 birds collected per
in north-central California reported low level mortality in three
groups of migratory birds. About 25 white pelicans and other fish-eating
birds found sick or dead on the south end of the Sea the second
week of March were confirmed with botulism type C. There was concern
that botulism could cause major losses of pelicans similar to the
large botulism mortality event last fall. About 2,100 dead and affected
eared grebes were found at the northwest end of the Sea exhibiting
the same abnormal behaviors that grebes have shown in past die-offs
at Salton Sea; preening excessively, coming out of the water to
preen on land, and congregating at freshwater outlets to drink.
The cause of this mortality and unusual behavior remains undetermined.
A small group of about 20 snow and Ross' geese, were found dead
in fields and on freshwater areas in February on the south end of
the Sea. Avian cholera was suspected as the cause of mortality but
diagnostic evaluation showed no evidence of the disease.
reported the deaths of 1,900 eared grebes due to trauma. Apparently,
the grebes became disoriented during a snowstorm and mistook snow
covered fields and streets as water and attempted to land. Over
2,700 grebes were rescued and returned to a nearby refuge. Similar
events have been documented several times in the last 20 years,
the most recent during the winter of 1991.
strike was diagnosed as the cause of death for 52 snow geese near
Columbus, Kentucky. All of the birds examined had fractured vertebrae
and extensive internal hemorrhage with no evidence of an infectious
process or gunshot wounds. Murray State University reports that
broken back syndrome has been documented in geese in previous lightning
Over a period
of four months, four bald eagles died and five became sick after
feeding on euthanized carcasses deposited in landfills in Polk and
Volusia County, Florida. Analysis of stomach contents and blood
samples revealed pentobarbital as the cause of the morbidity/mortality.
Surviving eagles were placed under the care of the Florida Audubon
Society. The responsible parties were informed on proper disposal
of euthanized animals.
hundred passerines died in the area of Zion National Park, Utah.
Homeowners reported an estimated mortality of 3-4 birds per day
at bird feeders. Salmonella sp. was isolated from several
of the birds submitted for diagnostic evaluation. This marks the
first documented report of significant passerine mortality due to
salmonellosis in Utah. Large-scale events occurred east of the Rocky
Mountains in 1993/94 and west along the Northern Pacific Coast in
For additional information please contact Dr. Scott Wright,
USGS National Wildlife Health Center - Disease Investigations Branch Chief, at 608-270-2460 or
Paul Slota, USGS National Wildlife Health Center - Support Services
Branch Chief at 608-270-2420.