Primary purpose
To document the quality and quantity of available habitat for selected wildlife species. HEP may be used in three planning activities: wildlife habitat assessments (including both baseline and future conditions), trade-off analyses, and compensation analyses.
Expertise needed
Team with designated voting members from each of the review agencies: (e.g., US Fish and Wildlife Service, US Army Corps of Engineers, US Environmental Protection Agency, State, and applicant/action agency). These individuals must have training and experience in the basic principles of fisheries and/or wildlife biology and be certified in HEP.
Applicable habitat types
Most terrestrial, wetland, and aquatic habitats in the United States.
Category assessed
Habitat suitability for selected fish, wildlife, or invertebrates.
Procedure
A team of experts selects a few evaluation species that could potentially use cover types within the study area and reviews applicable habitat suitability models (in separate USFWS publications). Models may also be developed by the team performing the evaluation. The models (a) identify the model variables, (b) assign a suitability index (scale 0-1.0) to conditions for each variable, and (c) include the equation for calculating the habitat suitability index (HSI). The team visits the study area (or reviews plans for predicted future conditions) to measure the habitat features listed in the models. The HSIs, habitat units (HUs), and average annual habitat units (AAHUs) are calculated. If there is a need to document value judgements in trade-off analysis, the relative value index (RVI) may be calculated.
Key Terminology
Average annual habitat unit (AAHU): the total number of HUs gained or lost as a result of a proposed action, divided by the life of the action.
Evaluation species: individual animal species, groups of species, life stages of a species, or life requisites of a species selected for purposes of analysis.
Habitat suitability index (HSI): unitless number bounded by 0 and 1 where 0 represents no habitat and 1 represents optimum habitat.
Habitat unit (HU): a value derived from multiplying the HSI for an evaluation species by the size of the areas for which the HSI was calculated (HU = HSI x size of habitat).
Output
Measures of habitat suitability of each cover type and the entire project area for each evaluation species. The HSI measures habitat suitability of a sample plot relative to optimum habitat suitability for a species in regions defined in the individual models.
Estimated time to assess 1 acre site
Total 40 hours for simple study (if models are available)
Total 64-240 hours for average study (if models are available)
8-24 hours: Determine applicability of HEP. Includes cost estimate. (step 1)
8-80 hours: Define study limits (step 2).
16-24 hours per cover type: Field time (step 3)
32-112 hours: Data analysis (step 3).
Total 128-336 hours (if models must be developed)
8-24 hours: Determine applicability of HEP. Includes cost estimate. (step 1)
8-80 hours: Define study limits (step 2).
64-96 hours: Develop draft models for species (16-24 hours per species). Assumes develop 4 species models for this example (during step 3)
16-24 hours per cover type: Field time (step 3)
32-112 hours: Data analysis (step 3).
Comparison of habitat types
Can directly compare habitats within the geographic ranges of the evaluation species.
Use as guide to design
The HEP models may be used as a guide to design. Users can refer to the model variables to determine which conditions increase or decrease habitat suit ability. Habitat suitability for the red-spotted newt is increased when the wetland is designed to have 100 % of the water area < 2m deep (variable V1). Each variable provides information on conditions that should be avoided. For example, to be suitable for the red-spotted newt, the distance to forested cover type must be less than 150m (variable V3). Finally, the information in the HEP models is useful because it provides design criteria with explicit measurements (e.g., percent of water area < 2m deep).
Contact person(s)
Adrian Farmer, U.S. Geological Survey, MidContinent Ecological Science Center, 4512 McMurry Avenue, Fort Collins, CO 80525-3400
phone: (970) 226-9420; fax: (970) 226-9230; e-mail: adrian_farmer@usgs.gov
L. Jean O’Neil, US Army Engineer Research and Development Center, Waterways Experiment Station, Vicksburg, MS 39810-6199
phone: (601) 634-3641; e-mail: L.Jean.O’Neil@erdc.usace.army.mil.
Related procedures
Several procedures are based upon HEP, but modified to reduce application and analytical time include: PAM HEP (Palmer et al. 1985), WHAMS (Palmer et al. 1993), and WVA (EWG 1994). WCHE (Schroeder 1996) is scaled from 0 to 1 to be used with HEP.
Extent of use/field testing
HEP has been applied to a variety of projects (e.g., oil wells, highway, golf course development, mining, and reservoirs). The extent of use is unknown; however, HEP is widely used on larger projects throughout the US. USGS, Biological Resources Division reports using HEP approximately eight times during the last two years (Pers. comm.: D. Stiehl, USGS, June 3, 1998).
Proposed future revisions
New species models are being prepared. Also, software computer programs are currently being prepared for existing HEP models.
Key References
U.S. Fish and Wildlife Service. 1980. Habitat Evaluation Procedure (HEP) Manual (102 ESM). U.S. Fish and Wildlife Service, Washington, DC.
U.S. Fish and Wildlife Service. 1981. Standards for the Development of Habitat Suitability Index Models (103 ESM). U.S. Fish and Wildlife Service, Washington, DC.
Additional Reference
Sousa, P.J. 1985. Habitat Suitability Index Models: Red Spotted Newt. U.S. Fish and Wildlife Service, Biological Report 82 (10.111). U.S. Fish and Wildlife Service, Washington, D.C.
(Note: There are numerous other publications, in particular the habitat suitability index models for individual species. Contact Richard Stiehl for complete listing).