Science / Medicine : Hunting the Mountain Lion : California’s Elusive Wildlife Population Poses a Problem
Because of the mountain lion’s highly secretive nature, California Indian tribes called it Nashdoitson --Spirit of the Mountains. Today the mountain lion, which ranges throughout much of California though rarely seen by humans, remains as elusive as ever--confounding scientists’ efforts to collect badly needed biological and population information.
As a result, the small scraps of population data that do exist on the mountain lion have become the focal point of one of the most emotional wildlife issues in California’s history. Just how many mountain lions exist in California and how many are needed to sustain a viable population are numbers in rigorous dispute.
The increasingly bitter controversy began last year when the California Fish and Game Commission ruled to re-establish a sport hunting season on the big cats, following a 16-year hunting moratorium.
The situation became more clouded in June when a Superior Court judge rejected the commission’s ruling, making it unlikely the state would be able to comply with environmental impact statement requirements in time to start the hunt Oct. 8 as scheduled.
The commission had based its decision on the Department of Fish and Game’s estimate that there are about 5,100 mountain lions in California--more than enough, the commission insisted, to sustain the loss of around 190 lions annually through sport hunting.
Those opposing the department’s move, including the Sacramento-based Mountain Lion Foundation and other conservation groups, argue that data are so scarce there may be only half that number.
Ironically, independent wildlife biologists--who say they have been virtually ignored during the controversy--say the immediate issue of whether to hunt isn’t biological at all--it is political.
“There is a lot of argument about how many mountain lions there are in California, but the fact is nobody knows--and it doesn’t really matter anyway,” said Rick Hopkins, a mountain lion expert who is a Ph.D candidate in wildlife ecology at the UC-Berkeley. “You can manage the population successfully without knowing exactly how many there are.”
Michael Kutilek, a professor of biology at San Jose State who has spent several years researching mountain lions, agreed. “The exact population figure isn’t important, but population trends are. Most (researchers) agree the current mountain lion population is healthy, although the animal is so elusive it is hard to say anything with surety, so the final question becomes a philosophical one--Is the trophy-hunting of lions acceptable?”
(Mountain lions are hunted with trained hounds which, although slower than lions, have greater endurance. Most mountain lions will climb a tree to escape the dogs and will remain there even in the presence of a hunter.)
However, biologists are quick to point out that to assure the long-term viability of the species, more must be learned about the mountain lion and its habits. “It’s more important that we learn how they interact with prey species and their environment,” added Hopkins. “Most importantly we need to know how they are being affected by the commercial and residential development of their habitat.”
But collecting reliable biological data on the big cats has been a difficult task. “Unfortunately there is no magic method of gathering all the information on mountain lions we need,” said Maurice Hornocher, a world authority on mountain lions, who is the director of the nonprofit Wildlife Research Institute and professor of biology at the University of Idaho. “Almost all predatory animals are elusive by nature and the mountain lion is perhaps the most elusive of all the predators.”
The Department of Fish and Game uses five primary methods to arrive at its population estimates. However, the department admits that counting mountain lions is not an exact science. “Anytime you come up with (mountain lion) estimates statewide it has to be considered soft data,” said Terry Mansfield, the department’s wildlife manager in charge of mountain lion studies. “But using all these techniques together gives us a good idea of how many lions there are out there.”
The methods include: charting trends in the number of lions killed by vehicles and by hunters with depredation permits; actual field sightings; track transects and radio telemetry.
The first three methods have drawn heavy fire from wildlife biologists and conservationists.
“Road kills and field sightings don’t buy you much,” shrugged Hornocher. “Many people cannot properly identify a mountain lion, so field sightings could be due to increased vehicle traffic--which is likely in California. It would be unwise to base any kind of lion population estimates on them.”
Moreover, the increase in reported livestock depredation incidents by mountain lions--which has jumped from five in 1971 to more than 60 annually in the 1980s--may be due to other factors than an increase in lions, according to biologists.
“If everything was equal you might be able to correlate increased livestock depredation with an increased lion count,” said Wayne Evans, assistant director of the New Mexico Department of Game and Fish, who has studied lions for 15 years. “But it has been my experience that increased depredation reports are more likely to show trends in how excited ranchers are about reporting livestock problems than in an increase in lions.”
The DFG’s fourth method of gauging lion populations, which is still in the development stage, is a technique called track transecting. Researchers drive slowly along dirt roads, or through snow, systematically searching for mountain lion tracks, which are carefully measured and recorded. Accurate track transects are difficult to develop, however, because the same animal can make different sized tracks depending upon soil types and whether it is going uphill or downhill.
For example, a lion traveling downhill will often slide in soft soil or snow, elongating its tracks. Moreover, mountain lions walk by placing their hind paws directly on the tracks made by their front paws, leaving a confusing overlay for trackers to measure. The fact that lions appear to walk on roads more often when they live in steep terrain and thick cover also can skew track transect findings.
“Because of all these variables it is clear to (biologists) that track transects should not be used to determine lion population densities at this time,” declared Hopkins. “All track transects can do is give you a general feel for the population, they won’t give you firm numbers.”
Radio telemetry--which involves tracking an animal that has been captured and tagged with a radio transmitter--is the most commonly accepted method of gaining information. But it is also the most expensive. Currently the DFG has about 40 lions wearing collars. “Ideally we would like to have a $2-million budget and catch and collar every lion in the state,” said Mansfield. “But given we only had $50,000 allocated for mountain lion research in 1987 that wasn’t possible.”
THE PROBLEM OF TRACKING MOUNTAIN LIONS Collecting reliable biologica data on mountain lions in California is a difficult task, says the Department of Fish and Game. Amont the methods: 1. Track transects (in which researcher measure paw tracks): Reports are inaccurate and difficult to develop because animals can make different sized tracks.
2. Field sightings: Many people canot identify a mountain lion, and repeated sightings skew reporting.
3. Count by vehicle kills: Any increase may reflect traffic as well as changes in lion population.
4. Radio telemetry (following captured and tagged animals): it is an expensive approach.
5. Count by prey: Livestock deaths may result from factors other than lion attacks.
