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Table 1 Predictors and variable importance scores in seasonal distribution models of the Western Arctic Herd

From: Using seasonal landscape models to predict space use and migratory patterns of an arctic ungulate

Included 2010 Predictors (units) Source Spring Calving Insect Relief Late Summer Fall Winter
Active Layer Thickness*∆ (m) www.snap.uaf.edu/tools/data-downloads 31.0 15.1 16.6 15.6 31.4 18.4
Aspect (°) ned.usgs.gov 27.6 13.5 11.3 15.2 24.6 10.6
Coast Distance (m) www.asgdc.state.ak.us 43.3 23.6 18.3 24.0 42.9 34.8
Elevation (m) ned.usgs.gov 30.6 13.2 14.3 15.7 32.3 16.1
Freeze Date*∆ (Julian date) www.snap.uaf.edu/tools/data-downloads 9.7 4.2 3.1 5.3 17.9 7.3
Thaw Date*∆ (Julian date) www.snap.uaf.edu/tools/data-downloads 17.2 5.5 5.1 4.1 12.3 8.5
Fire History∆ (year) agdc.usgs.gov/data/projects/fhm 14.6 3.8 2.5 3.2 14.1 15.9
Lake Distance (m) nhd.usgs.gov 31.5 15.3 11.6 17.6 29.4 15.5
Growing Season Length*∆ (days) www.snap.uaf.edu/tools/data-downloads 32.8 9.6 6.2 10.0 51.2 16.0
Ground Temperature*∆ (°C) www.snap.uaf.edu/tools/data-downloads 36.6 14.8 11.7 15.0 64.6 21.3
NDVI Greenup Rate∆ (−0.2˗˗1.0) nhd.usgs.gov 25.6 13.7 11.7 16.1 24.8 10.7
Max NDVI∆ (−0.2˗˗1.0) alaska.portal.gina.alaska.edu/search 22.2 5.4 7.9 17.9 27.5 15.6
Potential Evapotranspiration*∆ (mm/yr) arcticlcc.org/products/spatial-data 69.0 100.0 100.0 28.1 100.0 35.5
Permafrost Probability (%) [91] 18.9 10.6 10.2 16.0 32.9 18.1
Winter Precipitation*∆ (mm) www.snap.uaf.edu/tools/data-downloads 100.0 13.0 8.0 57.6 47.1 25.3
Summer Precipitation*∆ (mm) www.snap.uaf.edu/tools/data-downloads 26.7 12.7 14.2 21.4 34.0 26.9
Spring Precipitation*∆ (mm) www.snap.uaf.edu/tools/data-downloads 31.5 25.4 6.7 15.8 27.8 19.1
Fall Precipitation*∆ (mm) www.snap.uaf.edu/tools/data-downloads 35.7 12.5 35.5 20.1 44.4 21.1
Stream Distance (m) nhd.usgs.gov 30.1 13.9 10.8 15.8 26.8 13.9
Road Distance (m) www.asgdc.state.ak.us 60.9 31.1 26.5 27.9 44.3 39.1
Max (Mar) Sea Ice Distance*∆ (m) [92] 53.4 18.7 12.9 17.1 41.8 30.9
Min (Sep.) Sea Ice Distance*∆ (m) [92] 58.3 47.5 16.4 21.9 43.2 37.4
Slope (⎕) ned.usgs.gov 28.4 13.3 12.2 17.9 34.8 13.0
Winter Snow Day Fraction*∆ (%) www.snap.uaf.edu/tools/data-downloads 11.6 2.8 14.1 24.7 20.6 100.0
Summer Snow Day Fraction*∆ (%) www.snap.uaf.edu/tools/data-downloads 18.1 10.0 6.1 9.3 14.8 10.0
Spring Snow Day Fraction*∆ (%) www.snap.uaf.edu/tools/data-downloads 25.2 7.2 7.0 9.0 16.1 13.6
Fall Snow Day Fraction*∆ (%) www.snap.uaf.edu/tools/data-downloads 26.6 7.0 6.9 100.0 23.7 19.9
Snow-free Date*∆ (Julian date) [62] 64.2 10.4 9.3 11.7 27.7 25.8
Winter Temperature*∆ (°C) www.snap.uaf.edu/tools/data-downloads 25.8 17.4 9.0 15.6 29.5 28.1
Summer Temperature*∆ (°C) www.snap.uaf.edu/tools/data-downloads 28.3 15.4 7.6 10.2 28.5 12.0
Spring Temperature*∆ (°C) www.snap.uaf.edu/tools/data-downloads 22.0 12.1 9.8 10.5 24.7 12.6
Fall Temperature*∆ (°C) www.snap.uaf.edu/tools/data-downloads 65.4 20.8 9.3 13.7 26.6 21.4
Distance to Trails (m) www.asgdc.state.ak.us 35.7 16.1 17.0 18.9 34.2 23.6
Terrain Ruggedness 17 × 17 (0–1) ned.usgs.gov 28.2 20.6 18.7 21.4 28.8 33.7
Terrain Ruggedness 3 × 3 (0–1) ned.usgs.gov 26.5 13.8 12.1 16.1 24.4 10.5
Community Distance (m) www.asgdc.state.ak.us 43.4 14.9 11.9 15.1 43.6 13.6
Wetland Distance (m) https://www.fws.gov/wetlands/Data/Data-Download.html 25.4 13.7 11.9 15.6 30.7 13.8
  1. Predictors denoted with an * are decadal means, and ∆ indicates dynamic predictors that change annually. Active layer thickness is the depth of ground that thaws and freezes each year. Freeze and thaw dates refer to the mean annual date of first freeze (or thaw) during 2010–2020. Fire history denotes the year of the most recent fire in a given area. Growing season length is defined as the number of days between the date of first thaw and date of first freeze. Ground temperature refers to the modeled mean annual ground temperature. NDVI (Normalized Difference Vegetation Index) is an infrared-based measure of landscape greenness indicative of biomass; green-up rate and maximum NDVI are annual metrics calculated from NDVI. Potential evapotranspiration (PET) here is the amount of evaporation that would occur over a year if a sufficient water source were available. Seasonal climate variables are decadal averages of downscaled seasonal totals. Seasons are grouped as follows: Spring (Mar.-May), Summer (Jun.-Aug.), Fall (Sep.-Nov.), Winter (Dec.-Feb.). Permafrost probability describes the distribution of near-surface permafrost. Distance refers to the shortest Euclidean distance to the nearest feature. Snow day fraction is an average of the percentage of days with snow on the ground. Terrain ruggedness predictors were calculated from slope and elevation using 2 moving window scales of 3 and 17 m, respectively. Predictor importance values are out of 100.0 with the top predictor always receiving the maximum