International Society For Endangered Cats

A Voice For The Wild Cats of the World

Lynx Make A Comeback In Colorado

By Ivy Schnepp

Riding from Denver to Vail while a picturesque heavy snow came down in an area most known for pristine slopes and luxury ski villages, it is easy to see why Colorado is a popular tourist attraction. But Colorado is also home to a rich landscape and a vast array of wildlife. While I was on a vacation in Vail, I interviewed Tanya Shenk, the lead biologist working on the Colorado Department of Wildlife’s Lynx Reintroduction Program.

During the 1970‘s the Canadian Lynx (Lynx canadensis) population in Colorado was extirpated mainly due to poisoning, trapping and development. In 1997, the Colorado Department of Wildlife (CDOW) initiated the Lynx Reintroduction Program.

Tanya Shenk was working as a researcher with the CDOW and she volunteered to be part of the program. She was selected and is now the head biologist. Shenk became involved with wild cat biology after working in South Africa on a research paper on African Lions with Michael G.L. Mills.

What was the selection process for determining which lynx would be part of the program?

The CDOW worked with trappers in Alaska and Canada (lynx trapping is legal in Alaska and Canada) and the trappers agreed to do live captures. In return, the CDOW paid the trappers more than what the pelts were worth. A main concern was to not harm the source population so trappers were not harvesting more lynx than normal or allowed for that season.

Initially, their selection process was fairly inclusive although clearly, they did not want injured animals as they would be off to a compromised start in the program. By the second year, they slightly narrowed their selection process to adults only, no juveniles. Juveniles are animals that are younger than one year of age. Shenk states that the cooperation of the trappers was one of the most positive parts of this project and that the trappers were happy to be part of the program. Animals were given identification codes based on where they were captured, the year of the capture, male or female and number. For example, “AK99F1” would be a female lynx captured in Alaska during the year 1999 and she was the 1st cat captured. Trappers’ cooperation was so great that Shenk states that she still receives emails from trappers checking on the status of the lynx they captured.

What are the main challenges encountered by the Lynx Reintroduction Program and other reintroduction programs?

All programs are different. Translocation of wild animals is difficult and the incredible dispersal capabilities of lynx brings a unique set of challenges. The bulk of the animals stayed in the core area, however there have been lynx that have traveled to New Mexico and other states surrounding Colorado. By this time, most of you are familiar with the lynx who traveled 1200 miles from Colorado back to Canada where it was live trapped years earlier and placed in the reintroduction program. Technology, specifically the advancements in satellite collars and other tracking devices, has greatly benefited relocation programs. Another challenge the program encountered was the slow uptake to monitor reproduction which was not done until 2003.

Clarify definition of dens, your report refers to dens as being where young are raised but where do lynx normally sleep?

Lynx do not prepare dens because if there is a sign of danger, it is easier to move which is common behavior in carnivores, Shenk explains. “Dens” consist of a downed log(s) under which the females place their young. If Shenk notices that a female is in the same spot two days in a row, this alerts Shenk that either there was a big kill or the females has had kittens. On average, the lynx in the reintroduction program have litters of 2-4 kittens (average of 3). In Maine, there has been documented litters of 5. Normally, 1-2 kittens survive the winter. Female lynx are able to have a litter every year.

What is the snowshoe hare cycle and its role on the reintroduction program?

The lynx diet primarily consists of snowshoe hares followed by red squirrels. In other parts of the country, it has been documented that snowshoe hares follow a ten year cycle. There was a study on snowshoe hares in Colorado during the 1970s which developed a hypothesis that there wasn’t really a high cycle due to the patchy, dry habitat of Colorado. There have been two studies of snowshoe hares since 1997. Because snowshoe hares are not threatened or endangered, they have fallen down the cracks, so to speak, in regards to funded studies. At this time, it is unknown how snowshoe hares cycle but it is believed that they follow a 10-11 year cycle. However, (again) Colorado snowshoe hares do not follow the more extreme cycling that may be present in other areas so there isn’t the extreme highs and lows that are present in other snowshoe hare cycles. Lynx numbers cycle in response to population levels of snowshoe hares.

Do you think the mortality rate is normal or average for a reintroduction program?

From 1999 through 2006, 218 Lynx were released and as of May 2009, 115 lynx had died due to several mortality factors, ranging from illness to various human-induced deaths. Shenk states this is a good survival rate for the program and it is consistent or comparable with natural lynx mortality rates. About 30% of the mortality rate can be attributed to humans. There have been several cases involving the prosecution of individuals responsible for lynx deaths. Depending on the judges, some of those individuals receive fines. Lack of evidence in these cases is a major hindrance in successful prosecution. Also some people have a difficult time distinguishing the difference between lynx and bobcats, which are not legally protected which may play a small role in human induced deaths of lynx.

What is the Lynx Snow-Tracking Volunteer Program?

The CDOW unveiled a Lynx Snow-Tracking Volunteer Program which is a statewide effort to locate missing lynx (lynx whose collars were lost or no longer working) by searching for their tracks. Lynx tracking is difficult during the winter and volunteers are able to go into areas that would not normally be checked at their own pace. Shenk states that the volunteer program has been another really productive aspect of the reintroduction program allowing people to experience the outdoors in a new way.

What is a little known fact about Canada lynx?

Felids are solitary animals with the exception of lion prides and cheetah coalitions. Males generally play no role in raising their young. Shenk has documented the part lynx males take in rearing their young. They may not bring food to the young but they do protect the area where a mother may have her young located. In fact, Shenk has noted while monitoring females with kittens that the males stay quite near, guarding the area. This really stresses how interconnected these animals are. Say, for example, if the male is shot, this places the female and her kittens in jeopardy and a whole family may be lost.

Tanya Shenk’s message is a simple one amidst a complex reintroduction program comprised of understories, snowshoe hares and telemetry collars. It is so much easier to save a species in an area before it is extirpated than to try and relocate a species. Issues such as relocation, familiarity and dealing with captive wildlife all make relocation programs, an already challenging scenario, even more difficult.

More information on the Colorado Department of Wildlife Lynx Reintroduction Program:
CDOW Lynx Research Updates and Reports

CDOW Lynx Snow-Tracking Volunteer Program

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