Volunteers and biologists walking the beaches of northwestern Michigan's Sleeping Bear Dunes National Lakeshore the past few days have counted nearly 300 dead or dying loons and other fish-eating birds -- all victims of botulism that has scientists concerned about the changing ecology of the Great Lakes.
"This last couple days has been off the charts," said Dan Ray, a biologist in charge of a project monitoring the botulism among fish-eating birds at the park. "I'm sitting here looking at our graph and for the loons, this appears to be one of the worst seasons."
Strong southwest and northwest winds in recent weeks explain why the dead loons are coming ashore, possibly from many miles into Lake Michigan.
The death of loons -- with their haunting two-note cry and striking looks -- gets the public nervous, too, Ray said.
"It's almost strange from a biologist's standpoint," he said. "When loons show up (dead), people freak out."
On Tuesday, Ray walked 2 1/2 miles of shoreline near the mouth of the Platte River with Eleanor Comings, one of the volunteers, and found 88 dead birds, mostly loons. On Wednesday, Comings walked the same stretch and found 22 more loons.
After seeing today's story in the Free Press and on freep.com, several people have reported more dead birds, including loons. Calls and emails came from as far south as Onekema and as far north as Charlevoix.
Bernie Misko, who has a home on Lake Michigan about three miles north of the Portage Lake channel, said he found five loons on Tuesday while walking along the beach.
"One of them had coyote tracks walking up to it and around it, but it didn't bother" the carcass, Misko said.
The botulism issue, long a problem in southern U.S. reservoirs, first was a significant concern in Lake Michigan in 2006, Ray said, and was a problem again in 2007, but has been mostly in check the last few years. In 2011, only about 40 loons succumbed on the beaches of the national lakeshore, which Ray said seems to be like the end of a funnel where infected birds from northern Lake Michigan wash ashore.
Many of the birds are migratory, coming from Ontario, the Upper Peninsula and Wisconsin, as well as from northern Michigan, biologists said.
One loon found dead off the tip of the Leelanau Peninsula in late September was known as the Patriarch -- at age 21, the oldest banded loon in Michigan.
It had bred successfully from 2004 through this summer in wetlands along Lake Bellaire in Antrim County.
Thomas Cooley, a biologist and pathologist with the Michigan Department of Natural Resources, did the necropsy on Patriarch and determined that botulism killed him.
Besides their popularity with the public, there's another reason to be worried about the birds. "Any bird that's long lived with low reproductivity like a loon, any loss is a concern," Cooley said. "They'll produce only one or two chicks annually."
That compares to waterfowl like ducks that often have broods of 10 chicks.
Mallory King, a spokeswoman for the Michigan Audubon Society, said loons can live as long as 50 years, so Patriarch could have fathered many more chicks.
Loons are born in the northern climates and migrate to areas of the Gulf of Mexico as juveniles and return north to mate and reproduce.
Patriarch was born to loons nesting on Clam Lake in Antrim County in May 1991 and banded about a month later. He was rebanded in 2010.
The Michigan Audubon Society estimates Patriarch flew 42,500 miles before he died.
Blame mussels, gobies
The botulism bacteria killing the birds is linked to several invasive species that now thrive in the lakes.
Here is how biologists Ray and Cooley described what happens:
The problem begins with two tiny nonnative mussels -- zebras and quaggas -- that feed by filtering plankton in the water. Over time, water clarity increases, allowing sunlight to penetrate to greater depths.
In turn, that has allowed mats of algae to grow in deeper water. Meanwhile, another recent addition to the Great Lakes ecosystem -- the bottom-dwelling, minnow-sized round goby -- has proliferated.
As the algae mats decay, they become anaerobic -- depleted of oxygen, an environment in which the botulism bacteria thrives.
In some places, the algae blankets can be several feet thick.
Gobies live in and around the algae and pick up the toxin produced by the bacteria. In turn, susceptible fish-eating birds such as loons, mergansers and grebes, as well as gulls and cormorants, eat the gobies and become poisoned.
Botulism attacks the nervous system, leaving birds unable to control their wings and eventually, their neck muscles to lift their heads.
Death is slow and, at the least, unpleasant.
One theory suggests that the onset of fall weather and the turnover of the water column as the lakes cool could make the botulism toxin more accessible to fish and birds.
In the short term, little can be done to stop the die-offs. Regulators haven't figured out a way to eliminate invasive species like zebra and quagga mussels. And as other baitfish species like alewives and smelt have declined, gobies have become a favorite alternative for lake trout and, occasionally, salmon and other trout species.
Sport fishermen appreciate that.
What only time can tell
The volunteers walking the beaches have handheld GPS units, carefully marking the location of every dead bird.
They also carry shovels and bury birds away from the beach so that the toxin in their bodies isn't passed to eagles, coyotes or foxes that could come upon them and scavenge the remains, said Ray.
Ray said Comings and other volunteers are crucial to the park's efforts to help scientists track the carnage and keep poisoned carcasses off beaches.
On a few occasions, eagle deaths have been linked to botulism, and eagles are occasionally seen feeding on dead fish on the park beaches.
Occasionally, the dead fowl are banded. Those birds are sent to laboratories for necropsies.
Asked whether the worst of the die-off is over, Ray said: "I hope so. Time will tell. We've got a little bit of a south wind right now."
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