Grizzly bear (Ursus arctos) Prairie population, recovery strategy: chapter 3
3. Appendix 1
Arcview 9.2 (Environmental Systems Research Institute, Inc. (ESRI) 2006) was used to find suitable grizzly bear habitat through spatial analysis. This involved two processes: i) identifying secure habitats and ii) identifying the life ranges for each secure habitat.
i) Secure habitats were identified by overlaying the layers below that met the suitability criteria and resulted in polygons ≥ 9 km2.
Layer theme | Suitability criteria |
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Human density | Density ≤ 0.5 humans/ km2 |
Proximity to transportation corridors | Distance > than 500 m from roads or railways |
Land cover | Grassland, shrubs, trees, and wetlands. |
Landform type | Canyons, deeply-incised streams, mid-slope drainages, shallow valleys, upland drainages, headwaters, and u-shaped valleys. |
Proximity to lakes and streams | Intersects with a water course or type 2 water body (permanent water polygon feature, other than a slough, irrigation canal, or flooded area). |
ii) Life ranges were identified for each secure habitat using the following steps:
Layer theme | Suitability criteria |
---|---|
1. Circular buffer (900 km2) of secure habitat centroids | Radius = 16.925 km. |
2. Life ranges | Circular buffers with mean human density ≤ 0.5 humans/km2, mean road/rail density ≤ 0.6 km/km2, and land cover in cropland and hayland is < 10%. |
Layer theme | Data source |
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Human density |
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Proximity to transportation corridors |
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Land cover |
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Landform type |
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Proximity to lakes and streams |
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