Los Angeles Mountain Lions Are Hunting Closer to Homes Than Scientists Thought
Mountain lions have long roamed the hills of Los Angeles, but despite their proximity to the metropolis, they avoid human detection for the most part.
That doesn’t mean the big cats aren’t near humans or their houses.
A new study published in the journal PLOS One shows that the top predators in the Santa Monica Mountains National Recreation Area are hunting their favorite prey—mule deer—closer to urban settings than scientists previously thought.
The data showed that female mountain lions were typically found hunting closer to urban centers, while males prowled heavily wooded areas and near creeks and rivers.
The females could be hunting close to suburbia because human development is encroaching on their habitat, according to John Benson, a wildlife biologist at the University of California, Los Angeles, and the study’s lead author.
Male mountain lions pose a threat to females and their kittens, so they head to the next best hunting grounds: sprinkler-fed gardens and lush landscaping that attract deer.
“Females appear to be balancing a trade-off, where they may be willing to accept the potentially negative consequences of hunting near humans to avoid running into dangerous males,” Benson said. “Hunting in areas near development may be the lesser of two evils for female mountain lions.”
Greater Los Angeles area in Southern California, where researchers studied mountain lion predation on mule deer.
The findings come from data accumulating since 2002, when the National Park Service scientists began putting GPS collars on mountain lions in the region. Since then, researchers have tracked 26 mountain lions. When they noticed an animal’s GPS signal lingering in one area for most of the day, they trekked into the range to see if a kill had been made.
They logged a total of 420 mule deer kills, a majority of which were found within three-quarters of a mile from developed areas.
Seth Riley, the wildlife ecologist with the National Park Service who coauthored the study, said the findings show the adaptability of the top predators and the need to develop migration routes for a species whose range runs from the Pacific Ocean on the west to highways on the north, east, and south.
“The fact that we have a large carnivore living within the borders of one of the 30 megacities in the world is an amazing thing,” Riley said. “It’s really a testament to the preservation of open spaces within an urban setting.”
Mountain lions are not listed as threatened in California, but only around 10 to 15 remain within the 240-square-mile Santa Monica Mountains National Recreation Area.
Typically, one male mountain lion can command a range up to 200 square miles; for females the range is around 75 square miles. That puts the few cats in the L.A.-area mountains in danger of frequently crossing paths. The leading cause of death for the region’s mountain lions is other mountain lions.
Highways act as barriers that keep other mountain lions from migrating into the region, leaving the L.A. cats with a small gene pool.
“There’s only a few males in the whole mountain range, and if you have a year where one gets hit by a car trying to cross a freeway, and another gets poisoned by a neighbor’s rat trap, and another dies in a territorial fight, that’s it—you’re done with mountain lions in Los Angeles,” Riley said.
Those concerns have led conservationists to push for the construction of a migration corridor across the 10-lane 101 Freeway—a $50 million project that would connect the big cat’s current range to neighboring mountains.
Riley said the corridor is key to the future of mountain lions and many other animal species in the Santa Monica Mountains.
“It’s been shown that salamanders, lizards, and even birds need these corridors to get across developed regions,” Riley said. “We’ve known for decades that these animals need access to move freely, and studies like this are just making it more clear.”
The National Park Service, Caltrans—the state’s transportation agency—and legislators have voiced support for a wildlife bridge.
Beth Pratt-Bergstrom, California director at the National Wildlife Federation, said she is hoping to raise more than $10 million for the bridge by 2017 to complete the environmental assessment and the rest by 2019 so construction can start by 2020.
“These cats have shown how adaptable they can be to survive in their current situation, but the science is there—these animals need corridors to move about and thrive,” Pratt-Bergstrom, who recently authored a book on the subject of wildlife as neighbors, said. “And people are responding to this; we’re getting local donations, donations from Florida, and even as far away as Paris. People care.”
Benson and Riley are working on analyzing the GPS data and the genetic records the National Park Service has kept since 1996 to predict the likelihood of mountain lions surviving in the region for another 50 to 100 years under current conditions.
“We aren’t yet publicizing those results, but on our current trajectory we expect genetic issues to start causing problems for this population unless they can increase dispersal,” Riley said.