LOS ANGELES (Reuters) - A California zoo walrus is due to give birth to a calf this month, in a fairly rare event that has only been recorded 11 times before in captivity in North America, park officials said on Friday.
The 16 year-old Pacific walrus named Uquq is expected to give birth this month at Six Flags Discovery Kingdom in Vallejo, near San Francisco.
The park has three walruses, one male and two females, which were acquired as calves in 1994.
The animals have been slow to reproduce as the two females' breeding season did not match the rutting season of the male, which is named Sivuqaq, park officials said.
Despite the obstacles, Uquq was impregnated last year, and the pregnancy monitored by ultrasound -- the first use of the procedure on a walrus, park spokeswoman Nancy Chan said.
Because the park's walruses are trained, it was easier to get Uquq to lie down for the ultrasound, Chan said.
There have only been 11 walruses born in North American zoos and aquariums since records were first kept in 1931.
There are currently just 17 captive walruses at U.S. facilities, park officials said.
(Reporting by Alex Dobuzinskis: Editing by Tim Gaynor )