wolverine_habitat

Personal GeoDatabase Feature Class

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Keywords
Theme: wolverine
Place: Clearwater NF

Description
Abstract 
Clearwater National Forest Wolverine Habitat  2/24/10  

based on The bioclimatic envelope of the wolverine (Gulogulo): do climatic constraints limit its geographic distribution?
J.P. Copeland, K.S. McKelvey, K.B. Aubry, A. Landa, J. Persson, R.M. Inman,
J. Krebs, E. Lofroth, H. Golden, J.R. Squires, A. Magoun, M.K. Schwartz, J. Wilmot,
C.L. Copeland, R.E. Yates, I. Kojola, and R. May

Abstract: We propose a fundamental geographic distribution for the wolverine (Gulo gulo (L., 1758)) based on the hypothesis that the occurrence of wolverines is constrained by their obligate association with persistent spring snow cover for successful reproductive denning and by an upper limit of thermoneutrality. To investigate this hypothesis, we developed a composite of MODIS classified satellite images representing persistent snow cover from 24 April to 15 May, which encompasses the end of the wolverine's reproductive denning period. To investigate the wolverine's spatial relationship with average maximum August temperatures, we used interpolated temperature maps. We then compared and correlated these climatic factors with spatially referenced data on wolverine den sites and telemetry locations from North America and Fennoscandia, and our contemporary understanding of the wolverine's circumboreal range. All 562 reproductive dens from Fennoscandia and North America occurred at sites with persistent spring snow cover. Ninety-five percent of summer and 86% of winter telemetry locations were concordant with spring snow coverage. Average maximum August temperature was a less effective predictor of wolverine presence, although wolverines preferred summer temperatures lower than those available. Reductions in spring snow cover associated with climatic warming will likely reduce the extent of wolverine habitat, with an associated loss of connectivity.

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To allow for display and analysis of resource information

Supplementary Information 
We developed a spatial data layer of spring snow cover in the Northern Hemisphere for a 7-year period from 2000 to 2006 using moderate-resolution imaging spectroradiometer (MODIS) classified daily snow data (500 m spatial resolution) from the Terra satellite (Hall et al. 2006). Terrestrial pixels were classified into four cover classes (snow, bare  ground, cloud, night) for each of the 7 years (Hall et al. 2006). A portion of each daily MODIS image was typically obscured by clouds or, occasionally, by night. Generating cloud-and night-free images required compositing 21 consecutive daily images from 24 April to 15 May, which generally corresponds to the period of wolverine den abandonment (Magoun and Copeland 1998) and is consistent with the time period used by Aubry et al. (2007) to correlate historical occurrence records with spring snow cover. Compositing images reduced the number of cloud or night pixels during this period to <3% for all images. To separate areas where snow persisted through 15 May and to avoid confusion due to late ephemeral snow, we coded each pixel as bare ground if, during the 21-day period, the pixel was classified as bare ground at any time. This resulted in annual spring snow cover layers limited to areas with snow cover that persisted through 15 May. We then summed all annual snow layers for the 7-year period to create a coverage that depicted the number of years out of 7 that each pixel was classified as snow (hereafter, the spring snow coverage). We excluded regions of persistent glaciation (e.g., Greenland) and arctic regions  808N latitude from the spring snow coverage owing to predictably consistent snow cover during that time of year.

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