Official: Killing More Cormorants Key To Studying The Birds

Nov 8, 2010

<p><em><a href="mailto:stephanlj@interlochen.org">By Linda Stephan</a></em></p> <p>The federal government is hoping to decide this month whether to kill up to double the number of cormorants next season. The big, black migrating bird was once endangered in the Great Lakes region. Its rebound is a great success story, many would say too much of a success. </p> <p>After DDT was banned, cormorants rebounded in the Great Lakes and, for whatever reason, in numbers not seen before they were threatened. Their big numbers seem to cause all sorts of problems. So for seven years federal wildlife officials have been keeping their numbers lower, by killing adults as they fly near their nests and putting vegetable oil on their eggs so they won't hatch.</p> <p>But even after seven years of controlled kills, there are still plenty of "unknowns" about how the pesky birds affect the Great Lakes ecosystem.<em> </em></p> <p><strong>Better Science</strong><br />You might think scientists would by shy about killing birds, when they don't know their impacts. But that doesn't bother Russ Mason, head of Wildlife for the state Department of Natural Resources and Environment. </p> <p>He says that's part of the argument for killing more birds next year. Mason is leading the push to up the killings from a max of 10,000 birds to a max of 20,000 thousand.</p> <p>"What this allows us to do, essentially, is to set up a number of adaptive experiments so that we can manipulate cormorant numbers dramatically in an area and then look for recovery in fisheries, look for recovery in vegetation, look for impacts on other colonial nesting water birds in a number of locations to try to gather more holistic picture of what the impacts, the benefits of management might be, and also what the benefits, the impacts, of cormorants might be in various locations," he says. </p> <p>We hear a lot about how fishermen don't like cormorants gobbling up their catch. Mason says the birds can also "trash" an otherwise pristine habitat for wildlife. Plainly, the birds' excrement can burn out the vegetation on an island.</p> <p><strong>Areas Neglected</strong><br />So far officials have been killing in places such as South Manitou Island, and Beaver Island. Mason says there are many other places in Michigan where they'd like to kill cormorants because the birds could be a problem. But the current rule only allows them to focus on a few select areas around the state.</p> <p>"That focus then dictates that we will not be able, for example, to work at Ludington, or in southern locations, Saginaw Bay would be one, Lake St. Clair would be another," he says. "Shallow areas where cormorants could have significant impacts."</p> <p>Key is that, these are places cormorants could be a problem. We don't actually know that for sure, especially when it comes to the birds' impacts on fish. </p> <p>Data from northern Lake Huron links the birds with a collapse in a valued perch fishery there. But around Beaver Island the birds may be doing anglers a service, gobbling up the invasive round goby no one much likes.</p> <p>"Everyplace is a little bit different," says Pete Butchko. "Maybe some places are a whole lot different."</p> <p>Butchko is with the USDA Wildlife Division, the group that actually goes out to the islands to shoot the birds. It's also up to the USDA to decide whether to increase the cormorant kill next season.<strong></strong></p> <p>Butchko sees another unknown that could justify upping the kill.</p> <p>When a colony is disrupted by gunfire or egg oiling, birds tend to disperse and to settle in other places, potentially causing problems hundreds of miles away. That's actually why they showed up on Beaver in the first place, years ago.</p> <p>"You know, trying to predict where cormorants are going to go is, you know they'll go someplace, but how and what they'll do when they get there, so far that's kind of a murky process," he says.</p> <p><strong>People As An Ecological Unknown</strong><br />Generally, officials say they're inclined to listen to local fisherman when they see problems with the birds. But anglers' perceptions don't always play out in the data.</p> <p> "We might want to look at these birds in terms of the service they're providing, as well as an indicator of what's going on in the system, as opposed to just viewing them as a nuisance species," says Central Michigan University Biologist Nancy Seefelt.</p> <p>Seefelt has been studying cormorants around Beaver Island and she found herself at odds with local anglers after her research started to show the birds might be helping the Beaver Island fishery.</p> <p>The research didn't change the minds of those who already despise cormorants.</p> <p>And MDNRE's Wildlife chief says people's hatred for the animal is also an unknown factor in this ecosystem to consider. A person could cause real damage, for example, by dumping a wild pig on an island where it doesn't belong, in order to shoo off birds.</p> <p>So Russ Mason says decisions can't be made based on biology alone. Local people also have to feel their concerns are being heard. </p>