“As of November 18 we have recorded just over 2,000 dead birds on 93 miles of shoreline stretching between Peninsula Point in Delta County and Cathead Point in Leelanau County, an average of 21.6 dead birds per mile,” said Joseph Kaplan, a biologist with Common Coast Research and Conservation, a non-profit organization based in Hancock. “As a conservative estimate of the total shoreline distance between these endpoints is roughly 350 miles, 7,500 birds have potentially perished within this region alone.”
The die-off has been monitored by Kaplan’s group and others since October. The extent of dead birds being found has been reported further to the west in the Upper Peninsula to Menominee, to the south in the Lower Peninsula at Frankfort, and on islands, including Beaver Island and the Manitous.
The cause behind the avian deaths is thought to be avian botulism, a naturally-occurring phenomenon blamed for the deaths of about 2,600 birds last autumn downstate at Sleeping Bear Dunes National Lakeshore.
Officials with the Michigan Department of Natural Resources define botulism as a “paralytic condition brought on by the consumption of a naturally-occurring toxin produced by the bacterium Clostridium botulinum.”
Botulism has been a problem for fish and birds in lakes Ontario, Erie and Michigan. In a Michigan Sea Grant Web site notice, biologist Ken Hyde from Sleeping Bear Dunes said the recent Type E Botulism outbreak in the state has hit primarily fish-eating birds.
State DNR officials said that Type E toxin is found primarily in decaying fish.
“Poisonings in humans from type E botulinal toxins usually are associated with eating uncooked, imperfectly canned and improperly preserved fish and marine animal products,” DNR officials said in the Sea Grant notice. “Since fish-eating birds normally are not eaten by people and thorough cooking destroys the toxin, this wildlife source of type E toxin is not a serious public health problem.”
In the dead birds found by Kaplan’s group, the top five species were common loon (508), long-tailed duck (505), white-winged scoter (207), red-necked grebe (166) and merganser species, primarily red-breasted (127). Other species included red-throated loon, double-crested cormorant, ring-billed and herring gulls, horned grebe and bald eagle.
Kaplan said botulism out-breaks are not new on the Great Lakes, but this year’s appears to be quite large.
“We have been aware of waterbird die-offs on the Great Lakes for some time and decided to conduct surveys this season to try to quantify the scope and extent of the die-off as it appeared to be rather extensive,” Kaplan said. “Our efforts are by no means exhaustive and our coverage is limited to one-time surveys.”
Members of Kaplan’s group have been involved with long-term loon research and monitoring since 1990 at sites scattered throughout North America.
The focus for the group’s research is currently in the U.P. at Isle Royale National Park, Seney National Wildlife Refuge, the Ottawa National Forest, the Munising Moraine — including portions of Pictured Rocks National Lakeshore — and the Hiawatha National Forest.
Research of the group is focused on loon demographics and population dynamics, which are monitored through color-marked individuals. The group also tracks mercury exposure in loons using non-lethal methods of feather and blood sampling.
One of the dead loons found along Lake Michigan was a banded adult from Seney National Wildlife Refuge. It had been monitored on the refuge for 14 years and during that time produced 17 chicks, including one this past breeding season.
Of nearly 650 dead loons found (including birds from past years), only three have been juveniles and six have been second-year birds. This fact is a mystery to biologists, who are concerned for the long-term effects on loon populations. Loons are a long-lived species with limited reproductive capabilities.
“While we expected more adults than juveniles, this mismatch of adult to young birds is hard to explain and perplexing,” Kaplan said.
Above is a long-tailed duck that was found dead. Below are the remains of a common loon that was banded at Seney National Wildlife Refuge 14 years ago. (George Desort photos).