HABITAT SUITABILITY INDEX MODELS: PILEATED WOODPECKER

Equations. In order to determine the life requisite value for the pileatedwoodpecker. the 51 values for appropriate variables must be combined throughthe use of equations. A discussion and explanation of the assumed relationshipbetween variables was included under Model Description. and the specificequations in this model were chosen to mimic these perceived biological relationshipsas closely as possible. The suggested equations for obtaining thefood/ cover/reproduction value are presented below.Life requisiteEastern portion of range:Food/cover/reproductionCover typeEF.DF,EFW.DFWEguationLower of (V 1x V z x V J)I/ 2or (V~x V s)I/2Western portion of range:Food/cover/reproductionEF,DF.EFW,DFW .Lower of (V 1x V z x V J)I/ 2or (V, x V,)1/2HSI determination. The HSI for the pileated woodpecker is equal to thelife requisite value for food/cover/reproduction.Application of the ModelDefinitions of variables and· suggested field measurement techniques (Hayset al. 1981) are provided in Figure 2. Note that V~ and VI are to be measuredonly in the eastern portion of the range of the pileated woodpecker. and V,and V, in the western portion of the range.Variable (definition)Percent tree canopyclosure [the percentof the ground surfacethat is shaded by avertical projection ofthe canopies of allwoody vegetation tallerthan 5.0 m (16.5 ft)J.Cover typesEF,DF,EFW,DFWSugoested technigueLine interceptFigure 2.Definitions of variables and suggested measurement techniques.11