Trapped by busy freeways and by spreading suburban development, mountain lions that live in the Santa Monica Mountains of Los Angeles are losing their genetic diversity, which threatens their survival, experts say.
Completely isolated and unable to disperse in search of new mates, the animals exhibit behaviors like inbreeding between fathers and daughters, they say.
The resultant declining genetic diversity is also seeing bizarre behaviors such as male mountain lions killing offspring, their siblings or even mates, behaviors that would probably not be happening if there was sufficient movement between separate populations in the area, researchers said.
"Many of these phenomena, including very low genetic diversity and close inbreeding, have only been previously seen in Florida panthers, an endangered and completely isolated population of mountain lions," says Seth Riley of the National Park Service.
The freeways and development that surround the lions of the Santa Monica Mountains are likely causing the behaviors that should be rare or nonexistent if normal population and social processes could occur, he says.
The feline predators normally need a habitat range of 425 square miles to support themselves, experts say, while the mountains of Los Angeles only provide about 250 square miles.
Normally, in any mountain lion family group almost all the young male lions and around half of the young females eventually move out of the group to establish their own ranges, something the Southern California freeways and crowded housing subdivisions make almost impossible for the Santa Monica lions.
Although one male lion from an outside range moved into the Santa Monica Mountains during the period of the study, not a single animal was successful in dispersing out, the researchers say.
The isolation and hemming in of the creatures has resulted in damaging social interactions seldom seen in naturally functioning populations, says Riley, lead author of a study appearing in the journal Current Biology.
"There's almost no movement out," he says. "That's resulting in fathers mating with daughters, adult males killing close relatives or killing their offspring."
The genetic diversity in the lions in the Santa Monica Mountains is the lowest found in any population of lions living in the U.S. West, the researchers said.
The National Park Service has been working with California's Department of Transportation and a number of local agencies for more than ten years in efforts to secure funding for wildlife corridors or overpasses that would let the lions move past the barriers created by the local freeways.
