Female ospreys lay between one and four eggs in April or May. Chicks incubate for around a month, and remain in the nest another 60 days before taking flight. They’ll stay with their parents another two months while they learn to fish, but make their first seasonal migration alone.

Osprey nests, or aeries, are built from gathered sticks and typically located at high vantage points, such as dead trees, power poles or chimneys. Osprey pairs mate for life and return to the same nest year after year, adding to it each breeding season till nests reach heights nearing 10 feet.

There’s something fowl at the top of the U.S. Pavilion.

After reporting this week that they hadn’t found any bird nests as part of the demolition of the signature gathering place of Expo ’74, the Spokane Parks Department and Garco Construction said Thursday they had received photo evidence of an osprey family making a home 145 feet above the pavilion floor.

The Washington Department of Fish and Wildlife has been notified of the nest, and the construction team on the pavilion is working with the department to determine what to do about the nest at the top of the structure’s signature mast.

Carrie Lowe, an assistant wildlife biologist for the department based in Eastern Washington, said it’s not shocking that osprey would nest at the top of the structure.

“I’m not at all surprised. I think it’s genius,” Lowe said. “They’ve got a high vantage point. It’s a great place to hunt and stay safe from predators.”

The department will only issue permits for nest removal outside of hatching season, which ends Sept. 1, Lowe said. If the city wants to move forward with removal before then, they’ll need to seek approval from the federal U.S. Fish and Wildlife Service.

Clancy Welsh, Garco’s president, said earlier this week that construction likely wouldn’t reach the hanging wires of the pavilion until next spring. The pavilion is scheduled to be complete by the end of next summer.

It’s unclear how long the osprey have been nesting at the top of the mast, but Lowe said it’s likely been at least a few years. Osprey will return to nest in the same location year after year, she said, and that’s why biologists will recommend if the city does remove the nest, the city also install spikes and other permanent deterrence measures to keep the birds away.

Lowe said the just-completed demolition on the pavilion floor likely didn’t disturb the birds, known for defending their nests both vocally and with attacks against encroaching wildlife. She recommended against trying to capture an image of the osprey using a drone.

“We recommend aircraft stay about 800 meters from a nest. That’s a recommendation we follow,” she said. “As a department, we discourage (getting close with a drone).”

A provision in Washington state law prohibits the use of aircraft for hunting “or harassing any wild animal or wild bird.”

The department will also recommend installing a platform that could be used as an alternate nest location. That’s what was done in the Kendall Yards neighborhood, along the Centennial Trail, after some utility poll work displaced another bird.