When the Atlantic Club Casino Hotel shut its doors earlier this month, the kitchens and restaurants were shuttered, the gambling floor went quiet and the last guests all checked out. But one guest might return - and she hasn't heard the news. For almost 30 years - going back to when it was known as the Golden Nugget, Bally's Grand and the Hilton - a female peregrine falcon has made its nest and raised its young on the 23rd floor of the Atlantic City casino. And for almost all that time, zoologists have been stopping by to check in on the falcon mothers and to keep tabs on their chicks.

This year may even be one of the most important, with the possible arrival of a new female.

But what will happen now that the building is completely vacant and shuttered?

"Over the years - and I've been going there for so many years - I would make my way up (to the 23rd floor), and most of the time the jump door was locked," said Kathy Clark, a zoologist with the state Endangered and Nongame Species Program, which has worked with the nonprofit Conserve Wildlife Foundation of New Jersey to monitor and band the falcons. "Usually, I'd just call ahead to make sure it was open."

Atlantic Club staff would do more than just open doors. A falcon's nest was right outside the butler's kitchen, making it easy for staff to monitor when the mother would arrive in early spring and when her chicks hatched.

Head butler Mel Thompson, Clark said, was extremely helpful in observing the nest. He would even step out onto an open ledge to help keep away the concerned mother as the chicks were banded.

Clark said she hopes to work out details of access to the building with the new owners, Caesars Entertainment.

Caesars spokeswoman Katie Dougherty said she was reaching out to the state Department of Environmental Protection, which runs the Endangered and Nongame Species Program, about coordination. Dougherty added that Caesars, which purchased the building for about $15 million in December, does not officially take ownership until the end of January.

Clark said the birds have typically laid their eggs in April, "so we have a little bit of time. I told the folks at Caesars I'd like to get up there sometime in March."

Over the course of 26 years, Clark said, only two females have nested at the site.

The first one arrived in 1988 and returned every year until 2001. Another female arrived the next year and has nested there every year since.

"For all these years, it's kind of unusual having the birds live so long," she said. "It remains to be seen if the bird that nests this year is the same bird from 2002. It's pushing its successful lifespan."

If there is a new female, Clark said, the hope is that she will pick out one of the two "nesting trays" on either side of the 23rd floor.

"They're helpful in guiding the choice," Clark said. "Once the new bird shows up and is scoping out a new place on the ledge, we don't want her to nest just anywhere."

The tray used the most was the one just outside the butler's kitchen, at the side of the building overlooking the city, which was the easiest for the staff to monitor.

When chicks are about 4 weeks old and it came time for banding, Clark would bring the chicks into the penthouse suite to manually place bands on their legs.

One band would have a tiny number for tracking, and the other would be a distinctive color so it could be spotted at a distance - a necessary measure for a bird that will never come back after leaving its nest.

Banded birds usually leave after a few months and have been seen as far south as the Carolinas. But in the end, Clark said, they usually return to New Jersey. One banded bird was spotted in the Meadowlands, then in Brigantine shortly afterward.

In total, 54 chicks have been counted since the nesting began - including a record hatching of four in 2012. But 2013 was a dry spell.

"Last year, because of the age of the adult female, she actually didn't lay eggs," Clark said. "That's what happens when you get to the end of a lifespan. But she's still a ferocious bird, keeping out all competition."

But if it's finally the year for a new bird, "It's kind of fitting, since the hotel was sold, that we see a new female there. But that's yet to be seen," she said.

Of course, a new female moving in is not like a courtly passing of the baton.

"It's going to be a lot more violent than that," Clark said. "There's probably going to be a fight for that territory. Nesting areas are limited, and they try to nest on tall structures. It's prime real estate, so there's going to be battles. That's basically how nature works."

Contact Steven Lemongello:

609-272-7275

@SteveLemongello on Twitter

Peregrine falcons

Monitoring of peregrine falcons is a joint initiative of the state Endangered and Nongame Species Program and the nonprofit Conserve Wildlife Foundation of New Jersey.

For more information or to donate, visit www.conservewildlifenj.org.

For information on state endangered species, visit www.njfishandwildlife.com.