National Park Service researchers, together with biologists from the California Department of Fish and Wildlife, recently marked a four-week-old mountain lion in the Santa Monica Mountains. The good news is tempered by suspicion that the young female, now known as P-54, is a product of inbreeding.

The kitten’s mother is P-23 and the suspected father is P-23’s half sibling P-30. Researchers documented the two animals traveling together for three days and then, approximately 90 days later, saw a series of localized GPS locations, indicating that P-23 had recently given birth. If genetic testing confirms that P-30 is the father, it would the first documentation of him fathering kittens.

“The good news is that local mountain lions continue to reproduce successfully,” said Jeff Sikich, biologist for Santa Monica Mountains National Recreation Area. “Unfortunately, these animals are stuck on an island of habitat, with very little movement in and out of the Santa Monica Mountains, which has led to multiple cases of inbreeding.”

Southern California’s extensive freeway network has been shown to be a major barrier for wildlife and has particularly hemmed in the mountain lion population in the Santa Monica Mountains. A proposed wildlife crossing on U.S. Highway 101 in Agoura Hills would provide a connection between the genetically isolated population in the Santa Monica Mountains and the robust populations to the north.

This is the third litter of kittens for P-23, but in two previous cases her offspring were preyed upon by other animals. One kitten survived and was documented chirping for her mom. Researchers outfitted that kitten, now known as P-53, with a GPS collar in July 2016.

P-23 gained fame in 2013 when she was seen feasting upon a deer near a cyclist on Mulholland Highway.

This is the twelfth litter of kittens marked by National Park Service biologists at a den site. Two additional litters of kittens were discovered when the kittens were already at least six months old.

The National Park Service has been studying mountain lions in and around the Santa Monica Mountains since 2002 to determine how they survive in an increasingly fragmented and urbanized environment.

The California Department of Fish and Wildlife is responsible for overseeing the management and conservation of mountain lions in the state.

Santa Monica Mountains National Recreation Area (SMMNRA) is the largest urban national park in the country, encompassing more than 150,000 acres of mountains and coastline in Ventura and Los Angeles counties. A unit of the National Park Service, it comprises a seamless network of local, state and federal parks interwoven with private lands and communities. As one of only five Mediterranean ecosystems in the world, SMMNRA preserves the rich biological diversity of more than 450 animal species and 26 distinct plant communities.