highlights wildlife mortality reported to the National Wildlife
Health Center (NWHC) from October through December, 1995. Twenty
nine die-offs were reported to NWHC this quarter.
As is typical
for this time of year, avian cholera epizootics accounted for the
greatest losses. The largest die-off occurred at the Sacramento
National Wildlife Refuge Complex in California and involved over
5,000 waterfowl. Mortality began at Butte Sink NWR in early November
and later in the year occurred on the other Sacramento Complex refuges
(Colusa, Delevan, Sutter, Sacramento River, and Sacramento). Mortality
continued into early February. NWHC research personnel have been
on site collecting environmental data as part of an avian cholera
research project. Avian cholera also caused the death of an estimated
1,000 eared grebes and Canada geese using the Great Salt Lake in
Utah. Avian cholera occurred for the first time on this area last
year with losses estimated at 10,000 eared grebes and ruddy ducks.
In Scotts Bluff County, Nebraska, approximately 800 waterfowl, primarily
mallards, died on an open creek and a nearby ten acre pond. Low
level mortality is ongoing. This site is within 1/2 mile of an area
where avian cholera occurred in 1985. Avian cholera mortality has
not been reported again until this year.
in house finches continued in several Eastern states this quarter.
Sick birds were reported from a new location in Kenton County, Kentucky.
At that site, approximately 50% of the birds visiting a backyard
feeder were noted with red, crusty eyes. A single bird that was
collected and necropsied, showed lesions typical of the conjunctivitis
in house finches from previously documented sites. Mycoplasma cultures
were positive, however, the fragile organism could not be maintained
so typing was not possible.
caused the death of an estimated 60 waterfowl in Lassen County,
California. The area consists of flooded rice and alfalfa fields.
It is speculated that the source of the lead was from lead shot
spent in blackbird control operations.
1000 Northern fulmars died along the Pacific coasts of Washington
and Oregon. The mortality estimates were based on shoreline surveys
and with much of the shoreline inaccessible in this area, the estimate
is crude. The definitive cause of mortality is not yet known but
diagnostic testing is ongoing. So far there is no evidence that
infectious or toxic diseases played a role in the event. It is not
uncommon to find groups of dead fulmars and other seabirds following
storm events in the months of November and December, however, the
magnitude of the mortality in fulmars this year is unusual.
was determined to be the cause of death for an estimated 750 mallards
found along a one mile stretch of Winters Creek in Scottsbluff,
Nebraska. Mallards were found in a similar condition 2.5 miles away
on Lake Minatare. As many as 27 bald eagles were seen feeding on
the carcasses which, in conjunction with the poor ice conditions,
was determined to be the cause of death for 136 double-crested cormorants
in Runnells Bottoms, Marion County, Iowa. This is the first time
this disease has been reported in Iowa and it has only been documented
six times (1-NE; 1-MN; 5-KS) previously in double-crested cormorants.
Since the 1992 Newcastle outbreak, cormorant mortality has been
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.