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Mountain Lion Research

CHC Members Volunteer in UC Santa Cruz Mountain Lion Project

In May 2008 a study of San Francisco Bay Area mountain lions was initiated by the University of California Santa Cruz, the California Department of Fish and Game, and the Felidae Conservation Fund. The principle investigator is Prof. Christopher Wilmers of UC Santa Cruz. Research objectives include:

  • Capture and tag mountain lions for monitoring
  • Analyze mountain lion interactions with the natural and human world
  • Evaluate mountain lion behavioral response to increased human activity
  • Identify key habitats and corridors

Mountain lion capture specialist, Clifford Wylie, of the Department of Fish and Game, is assigned to the field team to capture mountain lions and fit them with tracking collars. Field biologist Paul Houghtaling of UC Santa Cruz leads the field team which includes field biologist Yasaman Shakeri and several UC students. Much of Paul’s effort is directed toward the time-consuming task of capturing mountain lions, which are among the most secretive animals on the planet. The field team responsibility also includes the collection and analysis of data, location of kill sites, documentation of prey at kill sites, interface with organizations that control land use in the study area and other functions. Given the size of the effort and the limited resources, Prof. Wilmers sought the participation of CHC field-team volunteers to assist Cliff and Paul in mountain lion capture.

Cliff, a CHC member, is a long-time houndsman, who has performed many mountain lion captures for various research projects during the past thirty years. In the early days (1970’s) tracking with trail hounds was the only method known to be effective in the location of the big cats. Cage traps and snares were developed as important capture methods as far back as the 1980’s. Cliff and Paul are skilled in the latter two methods. Tracking by trail hounds, however, remains a very important tool in this project. Expertise in the handling of trail hounds is the skill that CHC members bring to the field effort.

In March 2009, Mid-Peninsula Open Space District provided access to the Sierra Azul Open Space Preserve in Santa Cruz Mountains immediately west of San Jose. At that time CHC Board member Dan Tichenor, and later CHC President Josh Brones, and active CHC member Troy Collinsworth, joined the field team as volunteers to locate mountain lions in the study area by using trail hounds. CHC volunteers work with Cliff and Paul who are experts in the immobilization of treed animals. A dart loaded with the drug Telazol is used, because it is an effective immobilization drug, and the big cats can safely tolerate several times the required dose.

Location of mountain lions is made difficult by their low number density of about 6 adults per 100 square miles in good habitat. A lot of ground must be covered to find a track, and then it is likely to be many hours old. The hounds may have to cold trail for several miles before the track warms up. Nearly all of the hunting is done on bare ground without the aid of snow, which rarely falls in the study area. After sunrise the scent fades rapidly, so an early strike increases the chances of success. In the typical day in the field, CHC volunteers discuss the game plan with Paul and Cliff. Two hound trucks, if available, may start from different trailheads to cover as much ground as possible early in the morning. In some cases Paul places road-killed deer to attract lions to a site, where the approaching lion will trigger a field camera. The cameras are checked as possible strike opportunities. Once a track is found by sight, scent or camera, every effort is made to work the track and tree the lion.

Mountain lions exhibit a wide range of temperament, when treed by hounds. They often jump out and run, when people approach. Others may lie on a large limb with eyes closed, apparently bored by the encounter. Still others react to human presence by staring a person directly in the eye and showing their teeth in a wide gape, sometimes accompanied by a muffled growl. While such posturing is normally an idle threat, it commands the attention of anyone in close range armed only with a camera and a slow-acting dart gun. All of the lions pictured in this web site were treed by trail hounds.

When a lion is treed by a CHC volunteer, a cell phone call is placed to Paul or Cliff to describe the location of the lion, often defined by GPS coordinates. A treed lion provides an opportunity for mentoring university students, and for public education via photography and videography as well as for installation of a tracking collar. Since the big cat is not constrained in the tree, it is not subjected to a high-stress environment, and there is no urgency in darting the animal. Snares and cage traps on the other hand, constrain the animal and may subject it to stress, especially in the case of high-strung individuals. For that reason, these devices are monitored at fifteen minute intervals, and the drug is administered promptly to assure safety of the animal. While trail hounds provide more flexibility in time, the darting of a treed lion is more difficult than darting one constrained by a snare or cage trap.

For safety of the big cat, the reaction to being hit with a dart must be considered. Complete immobilization occurs in about four minutes with noticeable loss of coordination as early as two minutes. The lion often jumps out of the tree upon being hit with the dart and passes out on the ground. In that case one dog is used on leash to locate the tranquilized cat, bloodhound style. Sometimes the lion passes out in the tree and must be lowered to the ground by using ropes. The third possibility is that the lion drops out of the tree upon loss of coordination. The latter scenario is assumed, and the cat is darted only if it is low in the tree, and the landing area is free of large rocks and dead falls. With these precautions the risk of injury is very low. If the lion will not stabilize low in a tree, an attempt is made to jump the lion out and tree it again in the hope of finding better conditions for darting. In some cases, there is no safe opportunity to dart the treed lion, and the cat is released unharmed and without a tracking collar being installed. The process of locating the animal must start over the next day.

In most cases the cat is successfully immobilized so that researchers can examine the animal, make physical measurements, fit it with an advanced tracking collar, and acquire hair and blood samples. DNA analysis determines the kinship of individual animals in the study area. The blood analysis indicates the general health of the animal, and analysis of whiskers can provide information about diet during past months and years.

Much of the data gathered in this study comes from the advanced tracking collars. The collars use a GPS system to mark the animal’s location (waypoint) multiple times per day. Most of the collars use a cell phone to download the data to the research computer about once per week. A cluster of waypoints in the data, indicates that the lion has returned to the same location multiple times, typically after killing a large animal such as a deer or wild pig. The field team visits the site to identify the prey animal. A large cluster of waypoints in the data of a female may indicate a den site.

Custom designed collars in this study include an electronic device called an accelerometer. Acceleration data from this device can identify the type of activity the animal is engaged in such as lying, walking, trotting or attacking prey. This data should indicate the caloric needs of the animal. Perhaps the accelerometer data can identify events such as the utilization of small game, that may be consumed without leaving a waypoint cluster. Since this data is new to wildlife research, its full utility is yet to be determined.

The cooperative arrangement between UC Santa Cruz, DFG and CHC is working out very well. We believe this relationship will be enduring as plans progress toward the initiation of a complementary study in the East Bay.