When he looked at the "Falcon Cam," that's been aimed at an upper floor of a Seattle skyscraper for decades, Michael Donahue had one question: Where did the falcons go?

Donahue, who watches the birds from his desk at work, says the mother and father haven't returned to the nest for several days. They left four eggs behind.

"They just don't abandon eggs," said Ed Deal with the Falcon Research Group. "They're fiercely protective."

And they're loyal to their territory.

Since 1994, people have watched a succession of peregrine falcon pairs raise chicks at the former Washington Mutual building at 1201 Third Avenue.

From their high perch, peregrine falcons catch other birds in mid-flight, to feed themselves and their young.

The Washington State Department of Fish and Wildlife says this year's eggs are no longer viable, because they were last incubated on Saturday.

There are plans to take the eggs to the Burke Museum, where they'll be studied, according to WDFW.

It's unclear exactly what happened, but Deal suspects their mother died.

He said the father was spotted Monday and showed no interest in the eggs. Deal said it's early enough in the breeding season that the falcon may be searching for a new mate.

"This is nature," Deal said.

But it's a little disappointing to the Falcon Cam fans, who've been watching the Seattle birds long before the world waited for a giraffe to give birth in New York or an eagle chick to hatch in southwest Florida.

"Every spring, for the last few years I send an email to my brothers and sisters in various parts of the country and say, the falcons are back," Donahue said with a smile in his voice.

"It's that connection with nature that you lose in the city," said Deal, "and it's a way to reconnect with nature, even though you're in your cubicle you get to spend a little time in wild kingdom."

Life and death is part of that, and Deal is optimistic life will return to the Seattle peregrine falcon nest, soon.