CESI Modeling Project 98-4

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Individual-based Spatially Explicit Model of Cape Sable
Seaside Sparrow Populations
Louis Gross


The Cape Sable Seaside Sparrow was in the first group of species listed as endangered in 1967 by the U.S. Fish and Wildlife Service. Changes in water flows through the sparrow's range presently being evaluated for the Comprehensive Everglades Restoration Project (CERP) have the potential to adversely affect the present population. Because of this risk, any human-caused changes to the present hydrology must take potential impacts to sparrow populations into account.

The primary habitat for Sparrows is intermediate-hydroperiod marl prairies. Sparrows are spatially distributed in 6 populations (A-F), separated by areas of deep water or woody vegetation that are unsuitable sparrow habitat. Population A, to the west of Shark River Slough, is endangered primarily by flooding conditions that disrupt nesting cycles. Populations B-F, to the east of the Slough, are endangered primarily by conditions that are too dry, driving vegetation change and loss of suitable sparrow habitat by encroachment of woody vegetation into marl prairies favored by the sparrow.

This CESI-funded project helped evaluate potential impacts to sparrow populations to the west of Shark River Slough (Population A) using computer simulation. Researchers developed a relatively complex individual-based model that evaluated the number of potential nesting cycles per breeding season relative to nest flooding and computed the risk of sparrow extinction posed by alternative hydrologic scenarios. This model was not designed to evaluate hydrologic impacts to important segments of the sparrow populations (Populations B-F) to the east of Shark River Slough, where nest flooding is not the primary factor in endangerment.

A subsequent CESI project was funded to extend simulation capabilities to include sparrow populations east of Shark River Slough. This subsequent project produced the Hydrologic Impact Evaluator (HIE), derived from the ATLSS Sparrow SESI (Spatially-Explicit Species Index) Model, which evaluated the breeding potential of model cells under alternative hydrologic scenarios relative to the maximum number of potential nesting cycles per breeding season. The HIE produced a modified Index model for evaluation of flooding impacts, but has not yet incorporated the impacts of drought conditions driving loss of sparrow habitat for populations to the east of Shark River Slough.






Contact the principal investigator directly with questions about this study.


Spatially-Explicit, Stochastic, Modeling, Cape Sable, Seaside Sparrow, Gross, Donalson, Dong, DeAngelis, CESI, Critical Ecosystem Studies Initiative

Last updated: April 14, 2015

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