Estimating wolverine Gulo gulo population size using quadrat sampling of tracks in snow
Howard N. Golden, J. David Henry, Earl F. Becker, Michael I. Goldstein, John M. Morton, Dennis Frost Sr. & Aaron J. Poe
Golden, H.N., Henry, J.D., Becker, E.F., Goldstein, M.I., Morton, J.M., Frost, D., Sr. & Poe, A.J. 2007: Estimating wolverine Gulo gulo population size using quadrat sampling of tracks in snow. - Wildl. Biol. 13 (Suppl. 2): 52-61.
Low densities and wide-ranging behaviour make wolverines Gulo gulo difficult to monitor. We used quadrat sampling of tracks in snow to estimate wolverine populations. We conducted aerial surveys in upper Turnagain Arm and the Kenai Mountains (TAKM) in south-central Alaska and in Old Crow Flats (OCF) in northern Yukon during March 2004 following procedures for the sample-unit probability estimator (SUPE). This technique uses network sampling of tracks in snow in a stratified random system of quadrats or sample units. In TAKM, we sampled 87 (51%) out of 171 quadrats within a survey area of 4,340 km². The estimated density was 3.0 (± 0.4 SE) wolverines/1,000 km² with a coefficient of variation (CV) of 12.0%. In OCF, we sampled 96 (71%) out of 135 quadrats within a survey area of 3,375 km². The estimated density was 9.7 (± 0.6 SE) wolverines/1,000 km² with a CV of 6.5%. Our results indicated that the SUPE technique is an efficient method of obtaining precise estimates of wolverine population size under markedly different environmental conditions and population densities. We suggest that, where practical, it may be a less labour-intensive and more cost-effective technique for estimating wolverine abundance compared with techniques that do not use probability sampling of tracks.
Key words: Alaska, Gulo gulo, population estimation, sample-unit probability estimator, snow tracking, wolverine, Yukon
Howard N. Golden&Earl F. Becker, Alaska Department of Fish and Game, Division of Wildlife Conservation, 333 Raspberry Road, Anchorage, AK 99518, USA - e-mail addresses: howard.golden@alaska.gov (Howard N. Golden); earl.becker@alaska.gov (Earl F. Becker)
J. David Henry, Parks Canada, Kluane National Park, Box 5495, Haines Junction, YK, Y0B 1L0, Canada - e-mail: David.Henry@pc.gc.ca
Michael I. Goldstein, United States Forest Service, Alaska Regional Office, P.O.Box 21628, Juneau,AK99802,USA- e-mail: Goldstein.MI@gmail.com
John M. Morton, United States Fish and Wildlife Service, Kenai National Wildlife Refuge, P. O. Box 2139, Soldotna, AK 99669, USA - e-mail: john_m_morton@fws.gov
Dennis Frost, Sr., North Yukon Renewable Resources Council, P.O. Box 90, Old Crow, YT, Y0B 1N0, Canada - e-mail: vgrrc@yknet.ca
Aaron J. Poe, United States Forest Service, Chugach National Forest, Glacier Ranger District, Girdwood, AK 99587, USA - e-mail: apoe@fs.fed.us
Corresponding author:Howard N. Golden