THOUSAND OAKS, Calif. — Two new mountain lion kittens have been discovered by researchers studying the wild cats living in the Santa Monica Mountains, where fragmentation of wilderness by the sprawl of metropolitan Los Angeles and its freeways threatens the species.

The Santa Monica Mountains National Recreation Area said Tuesday that the kittens, which are male and female siblings, were found earlier this month by biologists with the National Park Service and the California Department of Fish and Wildlife.

The kittens have been added to the ongoing study as P-59 and P-60. Researchers say they are the first litter for a lion known as P-53.

The father is suspected to be P-12, the only lion documented to have crossed into the mountain range from the north.

DNA tests are pending.