Document Type

Honors Thesis

Major

Ecology and Environmental Sciences

Advisor(s)

Katharine Ruskin

Committee Members

Melissa Ladenheim, Brian Olsen

Graduation Year

May 2025

Publication Date

8-2025

Abstract

Atlantic coastal salt marshes of eastern North America have been altered by anthropogenic forces, including the digging of ditches for mosquito control, for hundreds of years. There have been few studies on how these ditches affect avian diversity in marshes. The implications of this are especially important given that one species, Saltmarsh Sparrow, is endemic to these habitats and is threatened by extinction in only a few decades if no conservation action is taken. Saltmarsh Sparrows may be vulnerable to the effects of ditching because ditching alters marsh habitat and marsh hydrology, which may increase incidence of sparrow nest flooding. Using modelled abundances of salt marsh specialists, generated from twelve years (2011-2023) of point counts from Maine to Virginia, and spatial data mapping ditches collected from several semesters of an undergraduate ecology course, I modelled the effects of ditch density on tidal marsh bird diversity (Simpson and Shannon diversity indices) and abundance of Saltmarsh Sparrows, controlling for patch area and latitude.

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