(e) = estimate; “suspect” = Diagnosis not finalized, but field signs and historic patterns indicate the disease.

CAHFS-Fresno (CHF), Florida Fish & Game (FL), Los Angeles Veterinary Public Health (LAV), Montana Fish, Wildlife and Parks Diagnostic Lab (MT), No diagnostics pursued (NON), National Veterinary Services Laboratory, Ames IA (NVL), USGS National Wildlife Health Center (NW), New York State, DEC, Division of Fish, Wildlife & Marine Sources (NY), Other (OT), Southeastern Cooperative Wildlife Disease Study (SCW), University of California-Davis (UCD), Unkown (UNK), Wisconsin Veterinary Diagnostic Laboratory (WVL).

Written and compiled by: Nathan Ramsay, Anne Ballmann - Eastern US, Krysten Schuler – Western US, and Rachel Guy - Technician

To report mortality or receive information about this report, please contact the USGS National Wildlife Health Center, 6006 Schroeder Road, Madison , WI 53711

Quarterly Mortality Reports

Birds with excessive salt encrusted on their feathers were discovered by USFWS personnel at White Lake in Mountrail County, North Dakota in late June. Affected birds were alert and moving their wings, but were unable to fly. Mortality was estimated at 110 birds with Mallards, Gadwall, Eared Grebes, Ruddy Ducks, Franklin’s Gulls, Green-winged and Blue-winged Teal, Northern Shovelers, American Wigeons, and American Coots affected. Shorebirds in the area did not appear to be impacted. White Lake is a large, alkaline lake with a former salt mine nearby. Euthanized and freshly dead birds had brain sodium levels between 1370-1700 ppm, wet weight. Salt acts as a preservative against carcass decomposition so older mortalities (possibly >1-year-old) have been observated at this lake. In 1985, a die-off occurred at this same location after cold temperatures made fresh water from other lakes unavailable (Windingstad et al. 1987). Salt toxicosis also has occurred during summer months in hypersaline lakes where birds were affected in less than 5 hours of entering the water (Stolley and Meteyer 2004).

Stolley, D.S. and C.U. Meteyer. 2004. Peracute sodium toxicity in free-ranging Black-bellied whistling ducks. Journal of Wildlife Diseases 40:571-574. Windingstad, R.M., F. X. Kartch, R.K. Stroud, and M. R. Smith. 1987. Salt toxicosis in waterfowl in North Dakota. Journal of Wildlife Diseases 23:443-446.

Ranavirus returns to Washington County (RI)
Between mid May and mid June, Wood Frog tadpoles, Marbled Salamander larvae and Spotted Salamander larvae were found sick and dead in some Washington County ponds monitored by the University of Rhode Island’s Department of Natural Resource Science. It is estimated that 80,000 amphibians have died, including nearly all of this year’s cohort. Sick animals were lethargic and had hemorrhagic lesions in the ventral skin. Subsequent virus isolation of the skin, liver and kidney determined that these amphibians died from a Ranavirus sp. This virus has been the primary cause of several amphibian mortality events in various ponds through out the County since 2001.

Avian Cholera outbreak at Rush Lake WMA (IA)
During the first week of April, Iowa DNR personnel found dead and sick waterfowl of various species at a Palo Alto County Wildlife Management Area. The sick birds had weak necks; thick, mucoid discharge matted around their eyes; and mucus draining from their nares. Over the following six weeks, the IA DNR collected over 200 ducks and geese of 17 different species, including Greater White-fronted Geese, Northern Pintail, Mallards and Snow Geese. Pasteurella multocida was cultured from specimens submitted to NWHC indicating that avian cholera was the cause of this mortality event.

Mortality events in waterfowl attributed to avian cholera are more commonly reported in the winter months when flocks are stressed from seasonal migration and reduced food resources.

Trematodiasis at the Upper Mississippi River National Wildlife & Fish Refuge (WI & MN)
Migrating waterfowl have been found sick and dead on the Mississippi River’s Pools 7 and 8 again this spring. US Fish & Wildlife personnel collected 1312 birds and estimated there were 2210 – 2580 dead with American Coots and Lesser Scaup comprising 99% of the mortalities. Infections by the trematodes Cyathocotyle bushiensis and Sphaeridiotrema globulus were identified in chilled carcasses submitted to NWHC. These parasites are found in the lower intestines of infected birds and cause severe blood loss, electrolyte imbalance, and penetrating damage to the intestinal wall leading to death. An estimated 32,000 migrating waterfowl at the refuge have died as a result of trematodiasis since 2002.

Unusual behaviors reported in summering bats from the northeastern US (NY, VT, NH, CT, MA)
Increased numbers of calls to public health departments from citizens are being reported this summer in the northeastern US. Bats are being observed persisting in the open during daylight hours, increased numbers of live pups are falling to the ground at maternity roosts, and there have been 2 reports of pup abandonment. Anecdotal reports from several areas indicate a reduction in colony size compared to previous summers. State Rabies Labs of NY and CT report decreased numbers of Myotis lucifugus submissions, the species with the highest winter mortality estimates during the peak of White Nose Syndrome (WNS), compared to previous summers. Summer bat surveys are assessing individuals for wing lesions thought to be a sequela of bat white-nose syndrome. The NWHC is requesting fresh, intact bats found dead on the landscape from any state where mortality rates within a well-defined area and time period exceed the expected background mortality. In addition, individual bats with wing membrane lesions are being sought for examination. Contact your local state wildlife agency to report unusual mortality events and to arrange submission.

Cormorant mortality detected in multiple counties throughout MN
Several die-offs involving young Double-crested Cormorants are being investigated in 4 Minnesota counties that are estimated to have started the first week of July 2008. MN DNR biologists reported initial losses of 200 and 300 birds at rookeries in 2 lakes in southern MN (Meeker and Faribault counties). Another estimated 200 birds were displaying clinical signs of neck weakness, incoordination, inability to right self, partial limb paralysis, and tremors. Approximately 90 % of the hatch year cohort appears affected. Other bird species displaying signs of illness at a much lower numbers include American White Pelicans and several gull species. Additional reports from northern MN (St. Louis and Lake of the Woods counties) have found only dead birds at a lower proportion than that observed at the southern locations. Preliminary diagnostics thus far suggest avian paramyxovirus-1 in the Meeker and St. Louis locations. Additional tests are pending to rule out other disease agents such as botulinum toxin and West Nile virus. Increased cormorant mortality on the Canadian side of the Great Lakes region of Lakes Huron, Erie, and Ontario has been reported by Canadian Cooperative Wildlife Health Center (www.ccwhc.ca).

Request for Wildlife Mortality and Morbidity Event Reporting (All States)
The Quarterly Wildlife Mortality Report, published in the Wildlife Disease Association’s newsletter, is intended to inform wildlife professionals of wildlife events of interest to them. The authors kindly request that investigation reports of recent die-offs of mammals, birds, amphibians, and reptiles be submitted for inclusion in the publication and on the related webpage. Credit will be given to appropriate diagnostic laboratories.