San Diego

An egg laid Sunday by a California condor at the San Diego Wild Animal Park is fertile, park spokesman Tom Hanscom said Wednesday.

Park officials used a “candling” technique to determine whether an embryo was developing inside the egg, the second produced this year by a pair of condors named UN-1 and AC-4.

“This is their double-clutch egg,” Hanscom said. The pair’s first egg of the year, laid Feb. 21, was taken from the birds with the hope that they would “double clutch,” or produce another egg to replace the one taken. That first egg is expected to hatch between mid- to late next week. The two also produced Molloko in March, 1988, the first condor chick conceived and hatched in captivity.

The egg, discovered about 5:30 p.m. Sunday, was removed from the nesting area of female UN-1 and male AC-4 and replaced with a ceramic egg, Hanscom said.

“We decided it was too late in the (mating) season to expect a triple-clutch this year. We replaced the egg because we are interested in observing nesting behavior by these birds and we don’t want to risk a real egg to do that behavior research,” Hanscom said. “It’s our hope that they will exhibit normal nesting behavior and . . . take turns at the nest, at which time we will replace the ceramic egg with an Andean (condor) egg laid here.”

Hanscom said that although it is getting late in the season, some condors at the park are still displaying mating behavior. “There are no immediate egg-lay watches, but we still keep our fingers crossed,” he said.

Seven condor eggs have been laid this year. Four were fertile, two were infertile and one was broken in the nest.

The 28 California condors that remain, divided between the Los Angeles Zoo and the Wild Animal Park, are in a breeding program to replenish the species for release into their former range.