Project Summary Sheet

Project: Individual Based Spatially Explicit Model of the Cape Sable Seaside Sparrow Population in the Florida Everglades

Web Sites: ATLSS.ORG

Location (Subregion & County): The total system

Funding (Source): USGS Place-Based Studies

Principal Investigator: M. Philip Nott, PhD., The Institute for Bird Populations, Point Reyes Station, CA 94956 e-mail: pnott@birdpop.org

Project Personnel: Donald L. DeAngelis, Phone: 305-284-1690 e-mail: ddeangelis@umiami.ir.miami.edu

Supporting Organizations: USGS/BRD, NPS, ACE, EPA

Associated / Linked Projects: Component of ATLSS Program

Overview & Status: The Cape Sable seaside sparrow (Ammodramus maritima mirabilis) is an ecologically isolated subspecies of the seaside sparrow. Recent surveys estimate its population size at fewer than 6000 individuals, and its range to be restricted to the extreme southern portion of the Florida peninsula, almost entirely within the boundaries of the Everglades National Park and Big Cypress National Preserve. Declines have occurred in the sparrow population across its entire range, probably due to higher water levels in recent years. During the first two years of this study two related models for the Cape Sable seaside sparrow were developed. (1) A spatially-explicit species index (SESI) model that indexes the breeding potential of suitable habitat as the potential number of offspring that could be produced in a given year, given the hydrologic pattern influencing a given area. (2) A spatially explicit individual based population model, SIMSPAR, that simulates a population of Cape Sable sparrows, as a collection of individuals, on the dynamic landscape on daily time steps. The demographic model validated well when compared against available empirical data on population numbers in the "western" subpopulation and there is strong agreement between model "hind-casts" and the observed rapid decline since 1993. Both the breeding potential index model and the population demographic model have been used in evaluating water regulation scenarios for the Central and South Florida Project Comprehensive Review Study. The demographic model was subjected to thorough sensitivity analysis for a number of important ecological and life cycle parameters.

Needs & Products: This project provided insight on the effects of hydrologic and vegetation change on this federally endangered species. These include hydrologic restoration effects on the persistence of Cape Sable seaside sparrow populations and habitat modification and management strategies for enhancing and restoring decimated populations. By means of a spatially-explicit individual based stochastic modeling approach, this project has identified a number of highly sensitive life cycle and behavioral parameters. These include (1) adult and juvenile mortality rates, (2) maximum number of attempted clutches in a breeding season, (3) dispersal ability of after-hatch-year (AHY) individuals, and (4) search range of unpaired female individuals.

Application to Everglades Restoration: To date SIMSPAR has been used to assess the following proposed hydrologic scenarios: C&SF Comprehensive Review Study (Restudy); Alternatives 1-6 and 13D - October 1997 through July 1998; Experimental Water Deliveries Program, Modified Water Deliveries Project, and C-111 Project.