The two gulls, named Claudia and Charles de Gull, have two eggs in a nest they built atop a 5-inch cannon on the SS Jeremiah O'Brien, a World War II Liberty ship that took part in the D-Day landings at Normandy in 1944.
The baby gulls are expected to emerge from their eggs within a week, National Liberty Ship Memorial executive director Dennis Koller said.
"They're real close," he said. "It could even be a in couple of days."
Koller said this is the first time that a Western Gull couple has nested on the O'Brien, which is a National Historic Landmark currently docked at Pier 45.
"They're around us all the time, but we've never had a nest on our ship," he said.
Western Gull nests and eggs are protected but the Migratory Bird Species Act, so the all-volunteer crew aboard the O'Brien has been mindful of the nest, cordoning off an area around it to allow the gull family some privacy.
Bird enthusiasts can keep up to date on the gulls on Facebook or on the O'Brien blog