habitat suitability index models: eastern wild turkey - USGS National ...

4. Multiply the life requisite values for each cover type by the
relative area (%) of that cover type, and sum these products for
each life requisite.
5. To determine the overall life requisite values, enter the value from
step 4 for each life requisite into the appropriate SI graph
(Fig. 6a-c). The resulting index values are the overall life
requisite values.
6. The HSl for the entire study area is equal to the lowest of the
overall life requisite values.
Application of the Model
Summary of model variables. Fourteen habitat variables and three composition
variables are used in this model to determine life requisite values for
the eastern wild turkey. The relationship between habitat variables, life
requisites, cover types, and the HSl for the turkey are illustrated in
Figure 7. The spec ifi c trees that provi de food for the eastern wi 1d turkey
vary across the geographic range of the turkey. It is suggested that users
develop a specific list of both hard and soft mast producing trees for use in
Figure 2a and 2b.
Definitions of variables and suggested measurements techniques (Hays
et al. 1981) are provided in Figure 8.
Model assumptions. Despite the abundance of information and research
that has been gathered concerning the eastern wild turkey, their specific
habitat requirements are not well understood (Bailey and Rinnel 1968; Kennamer
et al. 1980; Little 1980; Hurst 1981). Numerous assumptions were made in the
transformation of the published habitat information on eastern wild turkeys to
the suitability index relationships and formulas used in this model. The
major assumptions in the model are listed below.
1. The habitat variables and life requisite relationships apply to the
entire geographic range of the eastern wild turkey.
2. Water is not a limiting factor.
3. Nest sites will be present if fall, winter, and spring food, cover,
and summer food! brood needs are met.
4. Optimal fall, winter, and spring food values may be provided by
crops alone, by the combined value of crops and mast from trees and
shrubs, or by the combined value of mast from trees and shrubs.
5. The relationships for hard mast were developed using data from oaks.
It is assumed that these relationships apply to all hard mast
producing trees.
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