Primary purpose
To document the quality and quantity of available breeding bird habitat during regulatory actions and when evaluating areas for acquisition.
Expertise needed
Ornithologist (field observer competent in bird identification).
Applicable habitat types
Developed for wetlands, but applicable to any aquatic or terrestrial habitat.
Category assessed
Breeding bird habitat quality, although in theory any taxa could be used.
Procedure
The user obtains breeding bird population data for the state (or other geographic area) and assigns base values to each wetland dependent species. A list species of breeding populations at each site is developed by using available information or by conducting a field study. Using the species list and base values, the total species points and species index are calculated. The wetland habitat type and size are determined and compared to an optimum size for that wetland type to calculate an area factor. This factor is then used to calculate of the faunal index.
Key Terminology
Area factor: a factor that describes the size of the study area relative to the optimum size for the same habitat type within the geographic region of interest. Optimum size is determined from a species-area curve. Area factor = 1.0 for the optimum size.
Base value: points assigned to each wetland dependent species within the state based on the number of breeding pairs (e.g., species with estimated breeding population > 5000 points = 10 pts, species with 2500-4999 points = 20 points).
Faunal index: an index used to indicate wetland habitat quality, calculated by dividing a measure of species diversity and uniqueness (total species points) by a factor that accounts for wetland size (the area factor).
Species index: an index used to indicate wetland habitat quality, based on breeding bird species richness and rarity (within state or other appropriate geographic area). Calculated by averaging base values for each species found within a site.
Total species points: sum of base values for each breeding bird species found within a site.
Wetland dependent species: species that requires wetlands for a major life function, such as reproduction or feeding.
Output
Measure of habitat quality of a site that incorporates diversity/rarity of wetland-dependent species and wetland size.
Estimated time to assess 1 acre site
Total 1 hour per site (if models are available)
1 hour per site: Calculate area factor (step 2), calculate faunal index (step 3), and summarize results (step 4).
Total 25-41 hours (if models must be developed)
24-40 hours: Calculate species index. Includes obtaining and assigning base values to data for the state (step 1).
1 hour per site: Calculate area factor (step 2), calculate faunal index (step 3), and summarize results (step 4).
Comparison of habitat types
Can directly compare habitats within the geographic ranges of the evaluation species.
Contact persons
Virgil Brack, Jr., 3D International, 781 Need Rd., Cincinnati, OH 45233
phone: (513) 922-8199; fax: (513) 922-9150; e-mail: "none"
Ted Cable, Dept. of Horticulture, Forestry, and Recreation Resources, Kansas State University, Throckmorton Hall Room 2021, Manhattan, KS 66506
phone: (785) 532-1408; fax: (785) 532-5894; e-mail: tcable@oz.oznet.ksu.edu
SE as guide to design
HAT should not be used as a guide to design, but may be useful in guiding site selection. HAT describes habitat quality based on breeding bird population data. It does not address or provide information on habitat structure or other elements important to design. HAT could be used to select restoration/creation sites. A high index near a proposed site might indicate that the area has a good habitat potential. A low index at an existing site could indicate that it may be a potential restoration site.
Related procedures
HAT is a modification of the Graber and Graber method (1976), a technique that uses avifauna as an indicator of habitat quality in Illinois.
Extent of use/field testing
HAT has been used in Delaware (see Cable et al. 1989). HAT was used in Indiana to rank wetlands for acquisition.
Proposed future revisions
HAT will be used to evaluate farmed wetlands as part of an EPA farmed wetlands project in Kansas (beginning Spring 1998).
Key Reference
Cable, T.T., V. Brack, Jr., and V.R. Holmes. 1989. Simplified method for wetland habitat assessment. Environmental Management 13:207-213.
Additional reference
Graber, J.W., and R.R. Graber. 1976. Environmental evaluations using birds and their habitats. Illinois Natural History Survey, Biology News 97:1-39.