Juliet, one of the city's two signature swans, is missing at Lake Cherful, where the pair have become the north Fulton County city's unofficial mascots.
Locals fear she is dead, possibly killed by a coyote.
They're holding out hope that she might be somewhere sitting on a clutch of eggs.
But veteran swan-watcher Claire Murray Johnson said that's unlikely, because Juliet hasn't been seen in almost two months.
"She's never disappeared when she's had babies," Ms. Murray Johnson said.
Several weeks ago, Ms. Murray Johnson and others searched for the mother swan on foot at the 30-acre Lake Cherful park but found nothing.
"Her main nesting area is on our property," Raleigh Cannon said. "I kept going down to that area, to see if she might be there, but she wasn't."
Last year, snapping turtles snatched two of the couple's baby cygnets.
But no one expected Juliet, a mature swan, to become a casualty of the lake's food chain.
Romeo and Juliet were introduced in 2003. Romeo's first mate, also named Juliet, died of a foot infection in 2002.
The city's civic association sprung into action, spending a few hundred dollars to bring in Juliet II.
Although swans mate for life, Romeo took to the new mate.
Townsfolk in Mountain Park are divided on what to do now. Ms. Murray Johnson isn't sure the aging swan will accept another Juliet.
Mr. Cannon thinks he would.
"A man is never too old to have a mate," he said. "Take it from a 77-year-old male."