Cormorants pose big problems on lakes, islands
Written by Dayton Daily News   
Sunday, 22 January 2006 11:39

It might be difficult to find many folks who have good things to say about double-crested cormorants. To be sure, the large, black, duck-like birds have few fans around the Great Lakes.

People who fish — especially those who make their livings fishing the lakes — certainly don't like them. Cormorants have, in places — especially in northern Michigan — decimated the stocks of yellow perch and other fish. Although there is little data to say cormorants have impacted fishing on Lake Erie (but keep an eye on the smallmouth bass population), you won't find charter captains singing their praises when the crews see large black clouds of the birds skimming across the surface of the lake. What they do say can't be repeated here.

Even naturalists employed by states touching the Great Lakes — who usually do not have an economically influenced view of wildlife — have very little nice to say about cormorants. That's because they see the damage cormorants have caused to many Great Lakes islands.

Cormorant numbers have exploded in recent years. And not only have they become a black plague on the Great Lakes, they are moving to inland lakes. There are 80 pairs at Grand Lake St. Marys and a few have been seen recently at Lake Loramie.

Perhaps the most obvious cormorant destruction can be seen on West Sister Island in Lake Erie's Western Basin. On a federally protected island that has for years hosted the largest Erie great blue heron rookery and also hosts egrets and black-crowned night-herons, cormorants have come in and taken over. They nest in trees once used by the herons, leave their droppings all over the ground, killing trees and other vegetation.

"It is the most important breeding colony of herons and egrets on the entire Great Lakes," said Mark Shieldcastle of the Ohio Division of Wildlife's Crane Creek research facility. "We have a tremendous responsibility to protect that island."

In July, biologists counted 3,800 cormorant pairs breeding on West Sister. In addition there were many juvenile birds. When once there were about 2,000 great blue heron nests on West Sister, there are now 900.

"The great blue will go to the mainland, because it can tolerate humans, but the other birds there can't, so we are worried about them," Shieldcastle said. "And it's not only the other birds, but the trees and plant life there as well."

Biologists had hoped to head off plant-life damage at Green Island last year. Green, off the west shore of South Bass Island, is uninhabited, which makes it a target for cormorants to settle — and that they have.

There were 15 cormorant pairs on Green in 2004. A year later there were more than 800 pairs and the rocky shore's natural color had already been turned to a disgusting bird-dropping white by early summer.

There are some species of plants on Green considered rare in Ohio. Soon they might be extinct.

As biologists have found in other states, the only way to reduce the cormorant threat is not to scare them away. It's to kill them. That might sound a bit harsh, but when you scare them away, they just become someone else's problem. And if you look at the several now-barren islands in northern Great Lakes, you will see it is a problem.

Last year, Ohio applied to the U.S. Fish & Wildlife Service for permits to kill cormorants damaging West Sister Island. (The cormorant is a federally protected bird.) It also wanted to get rid of all of the birds on Green. The feds only gave out 500 permits, however, so Ohio did away with 250 on Greene and 250 on West Sister.

Others states, in addition to sharpshooters, have oiled eggs to stop reproduction. But that's not an immediate solution. Since only mature cormorants reproduce, it takes a couple of years for the destroyed eggs to impact the population.

Todd Haines, manager of Wildlife District 5, which includes Grand Lake St. Marys and Loramie, said he does not want cormorants to get a foothold at those two lakes.

"We can't let them take over the way they tend to do," he said. "And we know if we just shoo them away, they'll just end up at another inland lake."

So Ohio is asking for permits similar to those on the Great Lakes, to shoot cormorants.

Ohio would like to reduce West Sister cormorants by one half and eliminate all on Green. It won't solve all problems, but should slow them down.

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