Distribution, abundance, and habitat associations of breeding marsh birds in mississippi tidal marsh

Abstract

Marsh bird abundance and habitat associations for Mississippi tidal marshes are poorly understood and this habitat type is declining at an alarming rate. From 2012 - 2013, I conducted point counts at 212 sampling locations and determined density estimates for Clapper Rail (Rallus longirostris), Least Bittern (Ixobrychus exilis), and Seaside Sparrow (Ammodramus maritimus). These estimates were used to model a priori hypotheses describing observed patterns in species distribution and life history requirements. Results indicate high spatial and temporal variability in species densities between sites, routes, and marsh complexes. Investigation into factors affecting this variability indicate that wetland availability, as well as plant community composition and structure, most influenced Clapper Rail abundance. Least Bittern abundance was most influenced by salinity, available emergent wetland, and vegetation height. Seaside Sparrow abundance was most influenced by unsuitable habitat, available emergent wetland, and vegetation composition.