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While the peregrines are away, the pigeons will play.

Salt Lake City's peregrine falcons are not using the nest box atop the Joseph Smith Memorial Building this spring, and pigeons — one of the raptor's favorite foods — have taken advantage of the vacancy.

People checking in on the peregrine falcons via the web cameras installed at the nest box instead will see the lowly birds.

The 2015 nesting season dissolved when a female falcon that had been at the nest box was found injured and captured March 29. The female, which a state biologist believes has raised 11 youngsters in the box since 2011, was diagnosed with aspergillus, a fungal respiratory disease. She remains in a wildlife rehabilitation center.

Bob Walters, a watchable wildlife coordinator with the Utah Division of Wildlife Resources, says she is recovering, but has some lingering issues.

"If it clears up, we will let her go," Walters said. "If it doesn't, it is logical she could end up as an educational bird."

Walters has spotted another pair of falcons hanging around the One Utah Center, at 201 S. Main St. He set up a nest box on the building April 21, but the birds have not been caught using it.

"Humans are pretty spoiled; we expect success," Walters said. "Nature doesn't always happen that way."

The free-loading pigeons may be soon be evicted and the cameras turned off.

"I'm an optimist. We will wait a little longer," Walters said.

Most peregrine falcons have already hatched this season, he said. "We are just waiting to make sure no falcons show up, and then we will likely close up the box."