31048 – Crater Lake NP Winter Wolverine Survey 2004 – 2005

Investigator’s Annual Reports (IAR’s) for Crater Lake National Park

Crater Lake NP Winter Wolverine Survey 2004 – 2005


Report Number: 31048

Permit Number: CRLA-2004-SCI-0002

Current Status: Checked in

Date Received: Mar 14, 2005

Reporting Year: 2004

Principal Investigator: Dr Michael Murray, Crater Lake, OR

Additional investigator(s): Ray Davis, Ric Schlexer

Park-assigned Study Id. # CRLA-04003

Permit Expiration Date: Apr 30, 2005

Permit Start Date: Feb 01, 2004

Study Starting Date: Feb 01, 2004

Study Ending Date: Apr 30, 2005

Study Status: Continuing

Activity Type: Inventory

Subject/Discipline: Mammals

Objectives: The purpose of this study is to determine the likelihood of a wolverine population currently existing in Oregon’s Southern Cascade region. There is no physical evidence of wolverines currently occupying the Southern Cascades. Although no formal survey has been conducted, there have been thirty-five reports of wolverines in the region between 1956 and 2000. Two documented reports pertain to Crater Lake NP (1979 and 2000) as well as two additional oral reports since 2000. Half of these reports were submitted by wildlife biologists during off-duty activity, plus a Park maintenance worker.

Wolverines are at risk, even in remote areas, due to sensitivity to human disturbance. This is of particular concern in the Oregon Cascades due to the relatively small size and narrow, stepping stone distribution of suitable wolverine denning habitat. Such limited current habitat configuration along with increasing pressures of human disturbance could cause a reduction or elimination of reproductive capability, displacement, and significant gaps between breeding individuals, resulting in population decline and loss of distribution. Past years of aerial wolverine (non-landing) surveys have noted human activity in remote areas of wildernesses including backcountry skiing, and the unauthorized practices of heli-skiing and snowmobiling on adjacent National Forests. Improvements in winter recreational clothing and equipment, as well as increasing popularity of nordic skiing and ski mountaineering has resulted in increased winter use in the region, a trend which is predicted to continue. In the Sky Lakes Wilderness on the Winema and Rogue River NF, a moderate increase in use is reported. For example, winter recreation use on Mt. McLoughlin in Sky Lakes Wilderness is reported to have increased over the past nine years from 46 to 1,017 Recreational Visitor Days (RVDs).

Findings and Status: During the 2004 survey season no positive detections of wolverine were made.

For this study, were one or more specimens collected and removed from the park but not destroyed during analyses? No

Funding provided this reporting year by NPS: 2000

Funding provided this reporting year by other sources: 33704

Full name of college or university: n/a

Annual funding provided by NPS to university or college this reporting year: 0


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