Burps in Sleeping Bear Bay?

Photo by Mae Stier

From staff reports

On calm days this spring when Sleeping Bear Bay resembled glass, some Glen Arbor residents with homes on Lake Michigan heard what they described as periodic burps, or the sounds of water gurgling in a pipe. On days with wind and waves, they heard nothing.

The sound may have come from two “propane cannons” on the North Manitou Shoal Light Station, commonly called “the Crib” which lies 4 miles from Pyramid Point, the closest spot on the mainland. According to Dan Oginsky president of the North Manitou Light Keepers, which acquired the Crib from the federal government in 2016, the canisters are used to scare away cormorants, large aquatic birds that nested on the lighthouse and covered it with “guano” poop after it was decommissioned by the government and sat empty for decades.

Read our November 2021 feature story about the North Manitou Light Keepers’ restoration of the Crib.

When Oginsky first visited the Crib on Labor Day weekend 2016, he could smell the bird feces 100 yards before they reached the lighthouse on Captain Jim Muñoz’s boat The Cutter. When they disembarked, his boots sank into 3 inches of guano. “There was a dead cormorant embossed in the guano. It was gross,” he said.

When they took over the Crib, the Light Keepers’ first job was to remove 150 bags of bird guano from the deck. “They are voracious” said Oginsky. “The damage they can do in a short amount of time is startling. The consequences range from aesthetic to substantively damaging the structure. An ounce of prevention is worth a pound of cure.”

Since taking over the Crib, the Light Keepers have tried the Bird-X audio deterrent and even fishing wire strung between the deck and the tower to ward off cormorants, but to little avail. Oginsky, who also owns the Main Street Gallery in Leland, learned that local vineyards use propane cannons to keep out harmful birds. For the third summer, the Light Keepers now employ that strategy on the Crib, too.

“It’s not 100 percent effective, but it helps mitigate the impact.”

Here’s how it works. The propane canisters are connected to 3-4-inch metal tubes. At intervals of 15 or 30 minutes, the propane builds air pressure in the canister and emits a loud puff of air. “If you’re close to it, it sounds a little like the sound of a shotgun, a burst of air,” said Oginsky.

The Light Keepers periodically rotate the canisters because the cormorants are smart enough to get used to their positions and might fill up the other side of the Crib with guano—and also to avoid emitting too much noise in any direction. The cannons are programed to shoot off between 8 a.m. and 10 p.m. between May and October, the season when the Light Keepers lead trips to the Crib.

The crew has visited the light house three times this year, with one tour the first weekend of June. So far they haven’t found any dead cormorants and no guano either.

The North Manitou Light Keepers are currently raising money for phase 2 of the Crib’s interior restoration so that one day the organization’s supporters and shareholders can stay overnight in the lighthouse. Last season they finished replacing the level 3 deck, which involved welding steel plates to prevent water intrusion. They’ll hold their annual Lightkeeper rally on July 20 at the Main Street Gallery in Leland. The event is open for the public to come and learn about the restoration project, after which ticket holders can join a cruise to visit the Crib.