Thursday, November 25, 2010

Explosion of the Double Crested Cormorants

Here's something you don't see every day: a native species pulled back from the brink of endangerment all the way to becoming a nuisance species.

Double Crested Cormorant

The double crested cormorant was a bird native to the Great Lakes whose survival was on the ropes. And now, partially due to the invasive round gobies that have ravaged inland lakes, the native double crested cormorant is becoming a nuisance species choking out ecosystems. Round gobies, in some parts, make up a third of the bird's diet.

Round gobies, if you're not aware, are an invasive species to the Great Lakes region introduced via shipping in the the St. Lawrence Seaway around 1990. They're pretty damaging and wipe out a lot of native fish and game fish.

Wiki Round Goby Pictures, Images and Photos

On one hand, it's great something native finally got a taste for a pretty damaging invasive species. The problem with invasives is usually that there's nothing to control the population and they go crazy and take stuff over.

On the other hand, it turns out the native double crested cormorant has found itself with an abundance of food that other birds aren't eating to the same degree, and now THEY'RE taking over.


I guess it's all about balance.

The island, owned by Point Pelee National Park since 2000, is meant to be a bird sanctuary. In 2008, it was mainly a sanctuary for the cormorants. Some herons and gulls nested there, and other varieties of birds stopped by during migration.

Parks Canada began shooting cormorants -- despite heavy opposition from animal-rights group Cormorant Defenders International -- in spring 2008 and has been doing so every year since then.

"Middle Island is a dying island," said Marian Stranak, Point Pelee National Park superintendent. "The population of double-crested cormorants is just too high for that ecosystem to sustain itself."

The park has a five-year plan to reduce the number of cormorants, which it will evaluate after the fifth year to determine success and plans for the future, Stranak said. Like the U.S. Lake Erie Islands, the goal at Middle Island is to help vegetation rebound, she said.

In other news: US Steel now has stricter regulations on dumping toxins in to Lake Michigan.

Concentrations of chlorine and cyanide will be cut in half and silver concentrations to a quarter, according to a Post-Tribune review of the permit, which still needs final approval. U.S. Steel uses chlorine to kill invasive zebra mussels in the water it takes in for cooling.

The mill's previous permit did not contain limits for cadmium, copper, nickel or silver, but the new one will. The stricter limits are a result of permit modifications and policy changes since U.S. Steel's last permit was issued in the early 1990s. That permit expired in March 1995.

Pretty sweet. And it sounds like US Steel is working with environmental groups to meet those goals.

Less toxic stuff in the Great Lakes means fewer toxins in the fish we eat. And the fish the cormorants eat. And the cormorants we eat.

Now there's an idea.

1 comment:

Dennis said...

Double-crested cormorants are under pressure just any place they nest or overwinter in large numbers. And like most colonial nesting birds they breakdown and destroy the native vegetation either through their acidic guano or by stripping the plants for use in their nests.

Park managers typically have traditional visions of what parks should look like. Natural settings aren't always tended and manicured. They frequently show the wear and tear nature's whims have left behind. Parks Canada has a history of protecting park plants that live at the northern extremes of their range. These plants are also under stress and do suffer at the "hands" of birds such as cormorants, but the loss of such vegetation is a natural process, and managers who ignore these processes are ignoring the reality of nature.