Recent death of mountain lion sparks renewed conservancy efforts

When a young male mountain lion was struck and killed on the southbound Interstate 15 near the U.S. Border Patrol checkpoint Dec. 26, he became the third lion killed in the general vicinity by cars in the past 20 months.

The death of the young lion reinforces arguments about improved wildlife pathways and solutions in the area for lions to safely migrate from between the Eastern Peninsular Range and the Santa Ana range.

"We have a network of stakeholders in this issue that had a discussion about this most recent death over the last couple of weeks," Pam Nelson, chair of the Santa Margarita group of the San Gorgonio chapter of the Sierra Club, said. "I think all of us agree fencing would be our No. 1 strategy right now. It's something that could be doable and is more cost efficient, along with making the I-15 Temecula Creek interchange more functional. Those are our two main goals right now."

A study published in May 2017 in the online journal Royal Society Open Science described the need for the animals to have the freedom to travel.

"Without the benefits of immigration, genetic drift and breeding among closely related individuals can lead to an accumulation of deleterious alleles and inbreeding depression, reducing population fitness and increasing extinction risk," the study said. "Immigration benefits populations primarily by increasing heterozygosity and allelic richness, both of which are critical for population persistence."

The concern is that without continued genetic diversity, the overall health of the mountain lion population in Southern California will diminish, resulting in inevitable extinction.

The study, written by Kyle D. Gustafson, T. Winston Vickers, Walter M. Boyce and Holly B. Ernest, indicated that over the previous 15 years, only seven mountain lions had crossed over I-15, four from west to east and three from east to west.

"However, only a single migrant (named M86) was detected to have produced offspring and contribute to gene flow across the I-15 barrier," the study said. "Prior to the M86 migration, the Santa Ana population exhibited inbreeding and had significantly lower genetic diversity than the Eastern Peninsular Range population. After M86 emigrated, he sired 11 offspring with Santa Ana females, decreasing inbreeding measures and raising heterozygosity to levels similar to pumas in the Eastern Peninsular Range."

That lion, researchers said, single handedly improved the overall health of the species in the area and underlined the need to create more pathways for them to roam since the animals have a range of 150 to 200 square miles.

While mountain lions aren't a threatened species – there are an estimated 6,000 mountain lions in California – they are classified as a "specially protected species" by the California Department of Fish and Wildlife.

And many believe that without improved pathways and a slowing of development in the area, they could be threatened very soon.

This time last year, conservation groups sued the city of Temecula after the city council approved a high-density mixed-use development for the foothills west of Old Town.

"The city council's Altair approval ignored scientists' warnings that developing the South Parcel will severely limit mountain lion movement in Southern California," J.P. Rose, an attorney at the Center for Biological Diversity, said in a news release. "It's deeply disturbing that the city refused to make reasonable modifications to the development to avoid damaging a critical corridor for these iconic predators."

The lawsuit, filed in Riverside County Superior Court, claimed that part of the development "sits on the 55-acre 'South Parcel' – the only passage left for wildlife to move between coastal and inland mountains through the Santa Margarita River, Temecula Creek and the Santa Margarita Ecological Reserve, which are adjacent to the project."

The project is on hold until the legal matter is resolved, and Rose said they were scheduled for a conference with the judge to set a briefing schedule earlier this week.

"We may be setting a hearing date," he said. "But right now, we don't have a clear timeframe on when the lawsuit is going to be resolved at this point."

Ecological advocates also contend that an existing underpass wildlife crossing where the Temecula Creek crosses I-15 is often inhabited by homeless encampments and other visible signs of human activity, which are deterrents for the animals using the crossing.

"We have to continue working on eliminating the human impact as best we can," Nelson said. "That would include the traffic noise and graffiti which is a big problem. At night is when the animals feel it might be safest to cross through, but they won't do it with the music and lights and the homeless issue down there.

Nelson said because the passthrough is on city property, she is working to get the city to patrol the area better and eliminate as much of the human footprint as possible.

"We would really like a better response from the city," she said. "We would like to get a better presence from the sheriffs to get down there on a more regular basis, which would really help a lot."

She said the coalition is working on forming a volunteer group to monitor and document the condition and goings-on in and around the pathway.

"The best we can do is form monitoring teams that would go down there and notate vegetation, graffiti and wildlife tracks," she said. "We just have to make sure its safe enough for them to be down there."

Jeff Pack can be reached at [email protected].