(e) = estimate; * = morbidity and mortality
National Wildlife Health Center (NW); California Department of Fish and Game -
Wildlife Investigations Laboratory (CA); Iowa DNR (IA); Minnesota DNR (MN);
Southeastern Cooperative Wildlife Disease Study (SC); Nebraska Game and Parks (NE);
New York State Department of Environmental Conservation (NY).
Written and compiled by Gregory Kidd, National Wildlife Health Center (NWHC).
To report mortality or if you would like specific information on these mortalities,
contact one of the following NWHC staff: Western US Kathryn Converse;
Eastern US--Kimberli Miller; Hawaiian Islands--Thierry Work. Phone (608) 270-2400,
FAX (608) 270-2415 or E-mail firstname.lastname@example.org.
National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711.
NOTE: Effective 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 alphabetical order.
There were 30 events reported to NWHC this quarter. A large scale bald eagle mortality event has occurred for the second
time in three years in southwestern Arkansas. In early November, bald eagles and American coots were found sick and dead
on De Gray Lake. From November through January, a total of 25 affected eagles were found on Lakes De Gray, Ouachita and
Hamilton. In general, the birds were in good body condition with no gross lesions. All ages and both sexes were affected.
The only abnormality noted in eagles and affected coots were microscopic changes in the white matter of the brain, described
by NWHC pathologists and others as vacuolar myelinopathy. This is the same lesion noted in the 1994/1995 mortality event.
Extensive diagnostic testing has ruled out bacterial, viral and parasitic diseases. It is most likely that the mortality is
caused by a toxin, either manmade or naturally occurring. Comprehensive toxicology testing has not, as yet, revealed a cause
for the deaths. This mortality event has been the focus of intensive diagnostic, research and field study. NWHC has been
working with a multi-agency task force on disease identification, management and prevention.
An estimated 50 migrating Canada geese died at Rice Lake in Lake Mills, Iowa during mid-October. Geese were reported
to be emaciated with swollen necks and lead poisoning was suspected. Necropsy examination confirmed the geese were emaciated
with extensive esophageal impactions, enlarged gall bladders and one goose had Aspergillus plaques in an airsac. Despite the
suspected diagnosis of lead poisoning, liver lead values were normal. Similar esophageal impactions have been diagnosed in
Canada geese secondary to fusariform mold toxicity. Similar die-offs of Canada geese have occurred in the midwest during the
past few years. Despite chemical analysis for the presence of tricothecenes, none have been detected.
Nebraska Game and Parks reported mortality of an estimated 1,500 mallards in a field near North Platte. Aspergillosis,
a disease caused by the Aspergillus fungus, was diagnosed as the cause of death. While Canada geese and mallards were
feeding together in the same field, only the mallards died. It is likely that the mallards were exposed to the Aspergillus
fungus by feeding on moldy grain from a source other than the field.
Lead poisoning was involved in three epizootics this quarter. In Lenexa, Kansas and Montgomery County, Ohio, Canada geese
apparently ingested spent shot from old trap/skeet range fallout areas. At Lac Qui Parle Lake in western Minnesota, lead poisoning
coincided with avian cholera with the lead poisoning being documented only in the mallards.
During late October, Wisconsin Department of Natural Resources reported mortality in American coots and lesser scaup from
Shawano Lake. Coots and ducks submitted to NWHC were diagnosed with verminous enteritis caused by Sphaeridiotrema sp. By
mid December, 1,441 coots, 593 diving ducks and 82 dabbling ducks had been collected. In past years, other lakes in the
area have had mortality associated with the parasite; this year, however, Shawano Lake was the only lake where the disease
The New York State Department of Environmental Conservation reported mortality associated with chlordane/dieldrin from
several areas in New York. The report is a combination of 12 separate cases diagnosed from the past summer. Chlordane was
used from the mid 1950's to the early 1970's for termite and turf insect control. Almost all uses were banned by the late
1980's. Unfortunately, this organochlorine pesticide has a half-life of up to several years and state personnel believe
chlordane related wild bird mortality will continue in New York through the 1990's.
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.