Mountain lions hunt and breed in the slopes above sparkling houses and suburbs, making Los Angeles the only major metropolitan city in the world with such a population. Some of these brave cats have become well-known, such as bachelor P22, who lives in Griffith Park, a steep area where the famous Hollywood sign can be found.
However, cougars, or huge cats, are in danger. According to new research, they are severely inbred as a result of habitat fragmentation, which is mostly caused by major roads and highways, particularly Route 101, which impede migration and gene flow. Experts predict that these L.A. lions will become locally extinct in the next decades unless connectivity is improved through the creation of wildlife corridors.Nine mountain lions in the Los Angeles area have either very high levels of aberrant sperm or kinked tails, both symptoms of a catastrophic lack of genetic variety, according to a study published recently in the journal Theriogenology. Two of the cats also showed testicular abnormalities, which are also recognized to be inbreeding symptoms. With only a few dozen lions in the Los Angeles area, this is a large fraction of the total population.
Some of these signs were discovered in lions around the metropolitan area and its outskirts between December 2019 and December 2020, as part of normal research efforts and roadkill necropsies. Only one cat with a kinked tail had been seen in the area before this research, and that was in 2019.
"Genetically, we've just crossed a threshold," says Audra Huffmeyer, a National Geographic Explorer and postdoctoral researcher in conservation biology at the University of California, Los Angeles.
More mountain lions must be allowed to wander freely into and out of the two most isolated places where they live, the Santa Monica Mountains northwest of the city and the Santa Ana Mountains to the southeast, if they are to survive in the long run.
Fortunately for the cougars, a massive new wildlife overpass will be built over the 101 in the near future, allowing them to cross safely. The project's ceremonial groundbreaking took conducted on Earth Day, April 22, 2022, and it will be completed in 2025.
Seth Riley, a wildlife scientist with the United States National Park Service who also lectures at UCLA, says, "I think this crossing can fend off extinction" for the Santa Monica species. "By enhancing connectivity, we are very convinced that it will be extremely beneficial to all [fauna], including mountain lions."Cats with a broad range
Mountain lions used to range across much of what is now the United States. By the mid-nineteenth century, widespread hunting, frequently encouraged by the government, had significantly restricted the cats' range, which had been confined primarily to the western half of the country. Cougars, pumas, catamounts, and their scientific name, Puma concolor, are names given to the felines that exist over much of Central and South America.Florida panthers, now classified as a subspecies of mountain lion by the federal government, have managed to survive in the wilds of South Florida. However, because they have no contact with any other group, they become severely inbred, producing large numbers of deformed sperm, testicular abnormalities, and kinked tails. The introduction of eight female Texas cougars in 1995, five of whom bred with Florida panthers, helped to reverse the population's decline and improve genetic variety.
According to Dave Onorato, a researcher with the Florida Fish and Wildlife Conservation Commission who wasn't involved in this study, three-quarters of Florida panthers observed in the 1980s had kinked tails and more than half had testicular abnormalities—a far higher percentage than is seen today in Southern California.
However, "they are starting to notice the indicators" in Los Angeles, according to Onorato, "which probably deserves setting the alarm bells screaming." (Learn how America's most endangered cat might be able to save Florida.)When it comes to proof,
For the past two decades, Riley and his colleagues have been studying mountain lions in the Los Angeles area.
Huffmeyer and colleagues gathered data on mountain lion sightings all around the Los Angeles area for their most recent study. Around a dozen cats exist in the Santa Monica Mountains, and up to 12 more live in the Santa Susanas, which are separated by Highway 101. According to Winston Vickers and Justin Dellinger, biologists at the Wildlife Health Center at UC Davis School of Veterinary Medicine, about 20 reside in the Santa Anas, southeast of the city, and much more live in the Eastern Peninsular Range, further inland.
Using camera traps, the researchers discovered three animals in the Santa Monica and Santa Susana populations with kinked tails between December 2019 and December 2020. A fourth had only one descending testicle and a kinked tail when researchers inspected it in person in the Santa Monica mountains.Huffmeyer also looked examined the sperm quality of five cats from the Santa Monica, Santa Ana, and Eastern Peninsular Range populations who perished after being shot, poisoned, or struck by a car. The sperm of these cats was defective in 93 percent of cases. According to Onorato, this is a large number, roughly equal to the percentage of malformed sperm reported in Florida panthers before they were genetically saved.
Providing assistance to the lions
More cats must be able to wander in and out of isolated communities in order to increase genetic diversity. The Wallis Annenberg Wildlife Crossing was dedicated on April 22 by a number of environmental organizations. The $90-million bridge will span 10 lanes of traffic on the 101 Freeway, allowing mountain lions, coyotes, deer, and other wildlife to move freely between the Santa Monica and Santa Susana Mountains.
The route was chosen because it is located in the Agoura Hills, a rocky area where wildlife is naturally drawn, and experts are confident that wildlife, particularly wide-ranging species like lions, will use it.
However, more wildlife crossings will be required to rescue cougars, such as those spanning Interstate 15, which connects the Santa Ana Mountains with mountain lion populations to the east. Huffmeyer believes that translocation, or physically moving cougars in from other areas to enhance the population's diversity, could be considered in the future. However, this is a last-ditch effort.
For the time being, experts are looking forward to the completion of the new 101 crossing—and the possibility of seeing mountain lions.
"A large quantity isn't required to produce a significant genetic effect," Riley explains.
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