It’s almost Hitchcock-esque when you walk on Interstate Island, the site and sound of thousands of gulls flying and screaming and pooping.
The smell is close to nauseating and the sound of birds so loud it forces people just a few feet away to nearly yell to be heard.
But the island (that some incorrectly call Bird Island) is an important place for birds.
Most everyone in the Twin Ports who has driven across the Blatnik High Bridge has probably wondered what’s going on down there, just upstream. Many boaters catch a whiff of the guano-covered island if they get downwind.
Never present here before, ring-billed gulls moved on their own into the Twin Ports in the 1950s, when two first showed up on Barker’s Island. More came, and they nested in various spots near the harbor in decades past but suddenly moved out to the predator-free island in the 1980s. Now, some 13,000 nesting pairs — 26,000 adults and thousands more chicks — are nesting almost exclusively on Interstate Island, a man-made island of dredge material created in the 1920s.
Other than an effort to keep gull nests about 30 feet away from the tern pens, there is no effort to manage or reduce the ring-billed gull population. It’s been fairly stable in recent years, wildlife experts say.
Fred Strand, retired Wisconsin DNR wildlife manager, said the island is serving a useful purpose as the home base for gulls that fly off to Canal Park, the Wisconsin Point landfill and local fields and golf courses looking for food.
“We don’t want all these gulls nesting on private industrial areas in the port. That could be a problem. So we let them hang out here,” he said.
In addition to the ring-billed gulls, 180 nesting pairs of terns and 20 pairs of Canada geese, the island is home to about 35 nesting pairs of larger, native herring gulls. The minority herring gulls are fiercely protective of their nesting spots on the island and will attack and kill ring-billed gulls that get too close. They even eat the ring-billed gulls.
By about Aug.1, their chicks old enough to fly, almost all of the ring-billed gulls will leave the island and head to other areas of the Twin Ports, looking for french fries, popcorn and, if they have to, bugs and worms on area fields and beaches.
Federal officials also hoped that endangered piping plovers might also nest on Interstate Island but, so far, that hasn’t happened, The birds generally prefer broad, gravelly beaches with no trees nearby, but their eggs would be vulnerable to gull predation.
Interstate Island is a protected bird sanctuary and is closed to the public from March 1 to Aug. 30 each year.