The ATLSS Cape Sable Seaside Sparrow Breeding Potential Index Model
                              Basic Model Description 
                           M. Philip Nott and Jane Comiskey 
                       The Institute for Environmental Modeling
                          University of Tennessee, Knoxville
                               Knoxville, TN 37996-1610
                          (Copyright University of Tennessee - 1997)
        As part of the Central and Southern Florida Comprehensive Study Review
        (Restudy) several future water management regimes have been proposed. 
        Each of these scenarios will affect potential breeding activity of the 
        Cape Sable seaside sparrow (Ammodramus maritimus mirabilis) 
        disproportionately across its range. We consider each of three distinct 
        drainage basin zones currently containing known sub-populations of the 
        We briefly describe these in order of importance relative to current
        total population level of the sparrow. The first of these areas
        includes the core of the sparrow's range and lies within the Long Pine
        Key / South Taylor Slough drainage basin (Ingraham Highway area). 
        Effects on this sub-population will be most significant to the population 
        as a whole.  Secondly, the westernmost sub-population occupies the East 
        Slough drainage basin adjacent to the western edge of Shark's slough below
        Tamiami trail. This sub-population has been most affected by changes in
        water delivery since 1992 which restricted breeding activity and also
        resulted in drastic changes in vegetation patterns (Nott et al. in
        press). Finally, we consider the peripheral and highly fragmented
        sub-population within North Taylor Slough (and the southern portion of 
        Northeast Shark Slough), which comprises only a small percentage of the 
        total population.
        We express the effects of proposed scenarios as changes in the spatial 
        pattern of breeding potential with reference to these three drainage 
        basins with separate sub-populations. For brevity's sake we refer to 
        them as the core, western and eastern areas, respectively.
        We estimate a sparrow breeding potential index (BPI) for those
        landscape cells which have the appropriate habitat type (Muhlenbergia
        dominated prairie) or on which sparrows have been observed to nest. The
        sparrow BPI model is driven by input data from the South Florida Water
        Management Model (SFWMM).  These data, which are provided as daily
        water depths for each 2 x 2 mile area in the region covered by the
        model, are processed by the ATLSS landscape model into finer resolution
        hydrology.  Water depths at the 500-m scale of resolution for ATLSS
        index models are based on a pseudo-topographic map which incorporates
        information from a 28.5-meter resolution vegetation map (see HYDRO___.DOC
        for a more detailed description of high resolution hydrology and
        The sparrow BPI reflects the duration and spatial extent of the annual
        dry season during which the water level in any cell remains below the
        nesting threshold level of 16cm. Computation of the BPI is based on
        knowledge of how hydrologic factors affect sparrow breeding success,
        including critical water level thresholds for each stage of the
        breeding cycle. We use water depth estimates to make spatially explicit
        predictions of the number of potential breeding cycles for each
        landscape cell. Each cell will have 0, 1, or 2 complete (45-day) cycles
        per breeding season.
        A sparrow breeding cycle consists of a period of exploration/mating (10
        days for first cycle, 5 days for subsequent cycles), nest building, egg
        laying, incubation of eggs, hatching, nestling stage, walking stage,
        and fledgling stage.  For sparrows to raise young successfully, a
        window of 45 successive dry days between January 1 and June 30 is required
        for the fledglings to reach the walking stage.  If a cycle is
        interrupted by rising water levels before the walking stage, we assume
        breeding was unsuccessful and the nestlings die.  A new cycle begins
        with the next dry day.
        We overlay the computed brood cycle grid with a habitat-type map,
        utilizing known habitat preferences for sparrow colonization to compute
        breeding potential indexes from cell by cell brood cycle counts.
        Sparrows nest on landscape cells of short hydroperiod marl prairie
        characterized by dense stands of graminoid species (typically
        Muhlenbergia), usually below 1-m in height, uninterrupted by higher
        vegetation (trees or shrubs that would give potential predators a perch
        from which to survey the nesting area.) The vegetation map used is the
        April 1996 version of The University of Florida Land Cover Classification
	developed to support the Florida Gap Analysis Program (FGAP) vegetation 
	map.  When selecting Muhlenbergia-dominated cells, we 
	exclude those 500-m resolution cells with lower than 15% overall 
	Muhlenbergia content, as determined by the proportion of constituent 
	28.5-m resolution cells categorized as Muhlenbergia (type 33) in the 
	FGAP map. In addition we include only those cells which are elements 
	of appropriately sized larger clusters of Muhlenbergia cells.  Breeding 
	potential values for each cell are weighted by the higher of two values: 
	the proportion of Muhlenbergia in that cell or a weighting factor 
	reflecting the number of sparrows observed nesting and how recently 
	birds were observed there.
        Using BPI estimates for cells with preferred habitat in each drainage
        basin, we plot time series graphs showing the percentage of available
        habitat in which successful breeding occurred over the 31-year period
        for which SFWMM simulated hydrology is available.  Three-panel maps are
        used to show spatial comparisons between breeding potential for two
        scenarios and display the differences between them.  We present maps
        which represent 31-year averages, and also construct comparisons for
        selected years (i.e. high, low and average rainfall years as well as
        other years showing significant trends).
        It is important to note that the sparrow BPI reflects the effect of
        hydrologic conditions for individual years. Obviously, sequences of bad
        years will have more serious effects than bad years interspersed among
        a number of good years. In the latter case the population may recover
        during the drier years.  Some compensation for effects of successive
        dry years is provided in the BPI by computing a multiplicative
        weighting factor which represents the mean over previous simulation
        years of a term reflecting short and long hydroperiod effects for each 
        Estimates of scenario effects on the temporal patterns of population size
        require use of the individual based demographic model currently
        being developed.  As the duration of wet year sequences within any
        scenario approaches the maximum life span of the sparrow, the
        probability of local extinction increases.

        Nott, M.P., O.L. Bass, Jr., D.M. Fleming, S.E. Killeffer, N. Fraley, 
        L. Manne, J.L. Curnutt, T.M. Brooks, R. Powell and S.L. Pimm. 1997. 
        Water levels, rapid vegetational changes, and the endangered Cape 
        Sable seaside sparrow.  Animal Conservation (in press).
        Lockwood, J.L., K.H. Fenn, J.L. Curnutt, A. Mayer and D. Rosenthal. 
        1997. Natural history of the Cape Sable seaside sparrow. Wilson 
        Bulletin (in press).
        Output associated with the ATLSS Cape Sable Seaside Sparrow Breeding 
        Potential Index Model. 
        In accordance with ATLSS file naming conventions, each file name will
        consist of the characters:  UVXXYYZZ.EXT
        "U" or "_"      => the Base, typically F for the F2050 base
                           or E for the C1995 base
        "V" or "_"      => the alternative scenario or base
        "XX"            => "BC" for the ATLSS Cape Sable Seaside Sparrow
                           Breeding Potential Index Model
        "YYZZ"          => 4 character mnemonic, described below
        "EXT"  = "PDF" or "TXT" or "DOC" => PDF, tabular text or documentation
        ATLSS Cape Sable Seaside Sparrow Breeding Potential Index  
        1. Maps
        Map outputs used to characterize results of the Cape Sable Seaside Sparrow
        Breeding Potential Index Model will consist of eight image files in PDF 
        file format.  Each map shows a "Set" of model results, comparing one SFWMM
        hydrologic scenario to another, following the conventions for ATLSS comparisons
        of two model runs.  Each map has three panels.  The left panel displays index
        values for either an alternative or base scenario; the right panel displays index 
        values for a base scenario (e.g., the Future without Project Conditions Case, or 
        F2050). The middle panel displays the cell-by-cell difference between index values 
        for the two compared scenarios (e.g., ALT-5 minus F2050).
        Grid cells in the left and right panels are color-coded to represent the 
        (positive) values of the displayed index, which range between 0 and 1.  Cell 
        colors in the center panel represent either positive (shades of gold) or 
        negative (shades of blue) differences between index values displayed in the left 
        panel and those in the right panel.  Color keys are provided at the bottom of 
        each map.  Each map depicts the model area at either a Fine (500-meter x 500-meter) 
        or Coarse (2-mile) scale of resolution.
        For each of six selected years, images will provide a spatial display of
        index values for that year.  In addition, an image file is provided for 
        the mean of all simulated years.  The selected years include years with 
        high, low, and typical rainfall, and several additional years that serve 
        to highlight differences between the compared scenarios.
        The mnemonic characters are composed according to the convention:     
            "YY"  =  Last two digits of the year     
            "ZZ"  =  CR - Coarse (2 mile) resolution,         
                     FR - Fine (500 meter) resolution     
        Listing of ATLSS Cape Sable Seaside Sparrow map files:
        File Name                     Time Period
        ------------     --------------------------------------------          
        UVBC69ZZ.PDF    A High Rainfall Year    (1969)
        UVBC70ZZ.PDF    Highlight Scenarios     (1970)
        UVBC77ZZ.PDF    A Typical Rainfall Year (1977)
        UVBC83ZZ.PDF    Highlight Scenarios     (1983)
        UVBC90ZZ.PDF    A Low Rainfall Year     (1990)
        UVBC95ZZ.PDF    Highlight Scenarios     (1995)
        UVBCMYZZ.PDF    Mean of All Years       (1965->1995)
        2. Time Series  
        Time series sets associated with the ATLSS Cape Sable Seaside Sparrow 
        Breeding Potential Index will display breeding potential values for three 
        applicable subregions only. These show percentage of available habitat in 
        which successful breeding occurred for each year.
        File Name                  Description
        ---------        --------------------------------------------------------
        UVBCTSZZ.PDF     Percentage of available habitat in which successful     
                         breeding occurred for each year in each of three subregions.  
        3. Histograms
        4. Tables 

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