Big catsfind survival diffcult




Mountain lions managing to survive in the Santa Monica Mountains do so with increasing challenges.

Researchers studying these large carnivorous cats find that the lions are almost completely cut off from other populations by freeways, which act as fences.

Due to their isolation, local mountain lions show dangerously low levels of genetic diversity, the researchers’ study shows.

In the past decade, only one young mountain lion has successfully come into the Santa Monica Mountains from elsewhere. The single male, who immigrated in 2009, successfully mated and substantially enhanced the genetic diversity of the entire population on his own.

Isolation of populations has made Los Angeles-area cats sensitive to individual behaviors.

“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,” said Seth Riley, wildlife ecologist for the National Park Service.

“In our case, the fact that lions in the Santa Monica Mountains are completely surrounded by roads and development likely leads to behaviors that would be rare or nonexistent if normal population and social processes could occur.”

Among those behaviors, Riley and his colleagues found evidence of close inbreeding events between fathers and daughters and killing of offspring, siblings and mates, all behaviors that the researchers suspect would be rare or nonexistent if sufficient movement between populations was possible. Normally 75 percent of young mountain lions—all of the males and half of the females— move to other areas.

To the researchers’ knowledge, no single young mountain lion has successfully left the Santa Monica Mountains during the study period aside from one possible exception, a single male in a tiny dead-end area in Griffith Park who may have come from the Santa Monica Mountains.

Increased connectivity is critical for the long-term survival of mountain lions and other wildlife in the region, Riley said.

Freeways were built without taking wildlife into consideration. As a result, the 101 Freeway is a development corridor with very little natural habitat on either side.

Riley says the National Park Service, the California Department of Transportation and other local agencies have been working for to obtain the funds for a wildlife crossing, ideally an overpass, for carnivores.

Wildlife advocates say that the one successful male immigrant shows it might not take many successful crossings for populations to improve their genetic outlook.

“If wildlife connectivity is not considered and planned for, or improved in places like Southern California where it has mostly been lost, large carnivores, which exist at very low densities and need to move great distances, will not persist.”

This article provided by NPS.



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