1. Criterion Rationale
1: Slope between 27-85 degrees Bighorn sheep prefer areas closer to Escape
Terrain
2: Prefer habitats characterized by rock outcrops Bighorn sheep prefer the inside areas of rock
outcrops
3: Prefer Open/Semi-Open Herbaceous
Vegetation Habitats
Bighorn sheep prefer inside areas characterized
by low open/semi-open herbaceous vegetation
4. Prefer to be Distant from Human Disturbances
(300 Meters from Roads & 200 Meters from
Trails)
Bighorn sheep prefer the farthest distance from
human activities
Habitat Analysis of Bighorn Sheep in Glacier National Park
Examining Suitability Under Different Overlay Techniques
Client: National Parks Service
The following four maps exhibit habitat suitability analyses under differing overlay application
techniques. The four techniques utilized were Boolean Overlay Adding, Boolean Overlay
Multiplying, Overlay Add with Unique Identifiers, and Weighted Overlay.
Technique Description
Boolean Overlay Adding This indicates area by only two parameters:
whether they meet every criteria or they don’t:
0 = All Criteria Not Met
1 = All Criteria Met
Boolean Overlay Multiplication This indicates how many criteria are being met
in a particular area (e.g. 1 = One Criteria Met, 3
= Three Criteria Met)
Overlay Add with Unique Identifiers This indicates areas according to which
particular criteria are being met. We are able to
indicate unique areas that have a single and/or
combination or criterion being met
Weighted Overlay This technique sets different weights to
suitability criteria and thus produces areas
according to different weighted factors. (For
example, areas farther inside rock outcrops or
farther away from human disturbances would
be given a greater weight than areas closer to
these factors)
Suitability Value Area (Hectares)
0 383826
1 23543
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
0 5 10 15 20 25 30 35 40 45 50
Hectares
Unit
Overlay Add w/ Unique Identifiers
2428
42315
180783
91754
66348
23543
Overlay Adding
0
1
2
3
4
5
Values Indicate Area (Hectares)
Overlay Multiplication
Area Dissemination