Date of Award

1-1-2013

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

First Advisor

Christopher E. Hill

Second Advisor

John J. Hutchens, Jr.

Third Advisor

Robert F. Young

Abstract

Salt marshes have low levels of vertebrate diversity yet extremely high rates of endemism. Two of these endemic species are the Saltmarsh (Ammodramus caudacutus) and Seaside Sparrow (A. maritima); the closely related Nelson's sparrow (A. nelsoni) winters exclusively on salt marshes. A previous winter study found that individual sparrows of all three species were highly faithful to specific banding sites, and that the relative abundances of the three species differed by site. I hypothesized that the reason sparrow assemblages varied among sites was that the three species' winter habitat requirements were different. All three species winter in salt marshes, but detailed habitat requirements of each species are largely unknown. Studying the relationship between habitat and abundance could improve predictions of how changes to the marsh habitat caused by sea level rise and coastal development will affect wintering sparrows. I sampled wintering sparrow populations by mist-netting throughout the winter at 18 sites in South Carolina. I also measured habitat data on a landscape scale and at the scale of vegetation cover in small plots. I built regression models to investigate the relationship between species abundance and habitat. I found that both sparrow assemblage and habitat composition differed among the five marshes and 18 sites. The habitat-driven models' performance was either not significantly different from or was significantly worse than null models which estimated sparrow assemblage structure from capture effort at each site combined with study-wide and site-specific capture rates for each species. The similarities in sparrow assemblages at sites shared by the present study and a previous study indicate that patterns in relative abundance are stable from year to year; yet poor model performance indicates that these patterns cannot be predicted by habitat as measured in this study alone.

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