MILWAUKEE — Building owners along the coast of Lake Michigan are getting creative in dealing with nuisance gulls, whose population has been growing for decades.
The birds nest on building roofs, chew through wires and leave droppings that can send nasty smells into the ventilation system. But federal law prohibits harming them or trapping and moving them, so some managers have turned to creative solutions such as lasers, noisemakers and ultrasonic waves to make the gulls uncomfortable, the Milwaukee Journal Sentinel reported (http://bit.ly/1bFYw5h ).
The birds — primarily ring-billed and herring gulls — are nesting on the rooftops of businesses from Green Bay to Milwaukee to Kenosha. Once they nest they can become territorial, dive-bombing customers and anyone else who comes near them.
"They are such a protective animal. If they are on your roof and you get near your roof, it's war, "said Sheldon Oppermann, president of the Building Owners and Managers Association of Wisconsin.
The gulls are protected under the Migratory Bird Treaty Act. Once they nest they can't be moved, even if they've settled alongside heating, ventilation and air-conditioning vents.
That's what happened at a convention center in downtown Milwaukee operated by the Wisconsin Center District. They nested near vents, and the smell of their droppings began to permeate the building, said Richard Geyer, the president of the Wisconsin Center District.
"We could smell it through the vents," Geyer said. "The gulls were nesting and they would feed their young, and their droppings — in summer it was just awful. We had to do something."
That something turned out to be a wire grid system the district installed across its roof. The wires are spaced to prevent gulls from folding their wings so they can land. The birds also avoid going under the grid, perhaps because they fear being trapped.
Geyer said the solution cost less than $100,000 and has been a "lifesaver."
The U.S. Fish and Wildlife Service will sometimes grant permits to deal with nuisance gulls by allowing someone to remove eggs from a nest or coat the eggs with corn oil to prevent them from hatching.
Others have found success by using a red laser to deter nesting, Randy Allen, a regional manager for Sun Prairie-based Wil-Kil Pest Control, said.
One condominium development keeps the birds away with a spray that smells like grape Kool-Aid, which the gulls don't like. Other building owners spread a nontoxic gel on roof edges, or use a system that delivers a small shock to the birds without injuring them.
From 1990 to 2009, North American populations of ring-bills have grown 250 percent, to as much as 10 million, according to Birds of North America Online.