Santa Monica Mountains lions 'fast disappearing'

P-32 as a cub. National Park Service photo.

For Scientific American, Los Angeles writer Adam Popescu steps back and examines the long-range prognosis for the cougars whose bad luck is to call the Santa Monica Mountains home. Stuck on an Island, and Fast Disappearing is the headline, and there is an overture to the potential hope offered by a proposed wildlife corridor over the 101 freeway near Liberty Canyon.

But, well, you know. 2015 has been a seriously downbeat year for the local mountain lion population, and the prospects are not good.

From the piece:

There’s only around a dozen lions left in the Santa Monica Mountains, the range running from the Pacific Ocean through Los Angeles, America’s second-largest metropolis. The area cats are trying to escape because they’re trapped on an island of habitat, fenced in by freeways, hostage to urban development and isolated from the rest of their population. The last documented fresh blood entered the area in 2009, when a single male successfully crossed the U.S. 101. That male mated once, and introduced much-needed fresh genes.

An adult male’s home range can extend over 500 square kilometers. The Santa Monicas encompass about 700 square kilometers. There’s simply not enough land for each of the several males left to establish new territory and find mates and therefore not enough fresh genetic material to keep this population stable.

To further complicate matters, inbreeding, lions killing one another over territory and for mates and rodenticide from eating animals infected by poison are also destroying their population. Sure, there are neighboring mountains with viable lion populations—the Santa Susana Range to the north, which borders Los Padres National Forest and Angeles National Forest to the east—but they might as well be on the moon, because lions can’t cross the freeway and simply can’t get in.

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Now the Santa Monica lions, the only apex predator operating within a megacity, live on borrowed time. “They’re looking for a way out,” [NPS biologist Jeff] Sikich says. “Especially young males. Out of all the young males we’ve followed in the Santa Monicas, and I think there’s been 16, none have lived to the age of two. All have been killed either by being hit on a freeway or running into the adult male in the Santa Monicas….”

Sikich estimates the carrying capacity for the region south of the U.S. 101, where his lions are trapped, is “one or two adult males, roughly four to six adult females and kittens, 10 to 15 tops,” numbers that “genetically cannot sustain a population in the future without connectivity to areas in the north, across the freeway.” Sikich doesn’t mince words when he says this group will die if something doesn’t change.

Previously on LA Observed:
Three more Santa Monica Mountains pumas found dead
Mountain lion P-32 killed crossing Interstate 5 near Castaic
A second lion escapes the Santa Monica Mountains over 101