Louise Nelle, News-Review
November 23, 2007
In early November, Gary Rentrop took a stroll along the Lake Michigan shoreline near his cottage in Cross Village and saw a saddening sight.
Lining a one-mile stretch of beach were dozens of dead birds, some half buried in the sand and others washing up onto the shore
“It's pretty devastating. I've never seen anything like this before,” Rentrop said. “The first thing I thought was there is something really wrong with the ecology of the lake. It caused me to make some inquiries of what was going on.”
After contacting environmental groups and the Michigan Department of Natural Resources, Rentrop learned that the die-off was the result of a Type E Botulism outbreak which killed nearly 3,000 birds at Sleeping Bear Dunes in 2006.
Rentrop reported his find to the DNR which came to 82 birds including: 27 red-necked grebes, nine common loons, 12 gulls, 12 bufflehead ducks and 22 cormorants.
Rentrop was not alone. Other Northern Michigan residents such as Ed and Trudy Timm of Harbor Springs have also reported dead birds. Just this past Sunday, the Timms were visiting Sturgeon Bay when they found 15 loons within a two-mile stretch. Ed said they had washed up onto the beach, were bloated and “not pretty.”
Totally shocked. That something that's absolutely a symbol of the lakes in this area was lying on the beach is just disturbing,” Ed said.
Environmental groups and DNR personnel have received several phone calls recently from area residents calling in about birds. One such individual was Mark Breederland - a Northwest Lower Michigan district educator with Michigan Sea Grant.
So far, Breederland has collected birds from Emmet County in the Cross Village area as well as some in Charlevoix, Good Hart and Antrim County. He sent the freshest birds to the Michigan Department of National Resources Wildlife Disease Lab in Lansing for testing.
“We don't really have any numbers yet. It all depends on the weather. Typically after a big blow on the lakes more of the (birds) will blow on the shore,” Breederland said. “I would bet that we're over the 3,000 birds we lost last year because of the large geography.”
Unlike in 2006 when the majority of dead birds were concentrated at Sleeping Bear Dunes, the range has expanded north all the way to Mackinac, Schoolcraft and Delta counties in the Upper Peninsula.
While Type E Botulism has been devastating to the bird population, Breederland said the birds pose no threat to humans
“There's really no linkage between those birds and humans and Type E Botulism,” he said.
However, because birds may carry other diseases or bacteria, Breederland said persons handling dead birds should take precautions and wear gloves.
Testing Breederland's birds, among others from various individuals and environmental groups, is wildlife biologist Tom Cooley from the wildlife disease lab. To date he has confirmed Type E Botulism as the cause of death for the following species: ring-billed gulls, herring gulls, white-winged scoters, common loon, long-tailed duck, red-necked grebes, horned grebes, piping plovers and Caspian tern.
Although Cooley has yet to test cormorants and mergansers, he said Type E Botulism is a likely suspect for deaths of those species.
How birds become exposed to botulism, Cooley explained, begins with a bacteria called clostridium botulism. This bacteria thrives in water with low oxygen levels producing a toxin that can get into sediments. Invasive species like quagga and zebra mussels filter the sediments and pick up the bacteria which they pass onto other aquatic life like round gobies which eat the mussels. From there, birds eat the fish.
Once birds are exposed, Cooley said, they become paralyzed.
“What (botulism) will do is it causes a paralysis and they become weakened,” he said. “They have difficulty walking, holding their wings up.”
Usually, death comes quickly. Birds have trouble breathing and if in the water may drown first because they cannot hold their head above water.
The theory behind the outbreak is that invasive mussels have not only helped pass on the bacteria but aided in creating the environmental conditions that promote botulism outbreaks.
Mussels filter water and as the mussel population has increased the water has become clearer. As a result, light can more easily penetrate the water increasing algae growth. This increase in algae and algae decay may lead to lower oxygen levels and therefore provide a better environment in which botulism may grow.
Cooley said the theory has not yet been proven.