Influence of anthropomorphic changes to landscapes on wetland birds on Mount Desert Island, Maine

Meghan Powell
Jonathan Atwood, Ph.D.
Department of Environmental Studies
The tidal-marshes of eastern North America and their connected watersheds are important transitional zones between terrestrial and marine communities (Reinhold 1977; Mitsch and Gosselink 1993). The Atlantic tidal marshes of North America support the highest level of vertebrate endemism among similar habitats anywhere (Greenberg and Maldonado 2006). The coastal location of tidal marshes, however, requires that they compete with people for limited space, as over 60% of the residents of the United States live along the coast (Burlington 1999). To better understand how the bird species of tidal wetlands are being affected by encroaching human development point count surveys were conducted during the breeding season on four watersheds on Mount Desert Island in Maine. Our study included historical data beginning in 1999 and 2002 and concluding in 2010 and 2011. We determined rate of development by locating the development on aerial photos for the years of the research. We calculated three community metrics for each visit to a survey point: species richness, relative abundance, and Simpson Index, as well as a species level abundance for Nelson's Sparrow (Ammodramus nelsoni subvirgatus) and Swamp Sparrow (Melospiza georgiana). As percent of development within the watershed increased, the relative abundance and the Simpson's Index significantly decreased throughout all of the watersheds, while species richness and the abundance of the wetland obligates showed no significant changes. Future research and more periodic surveys will help to understand how the development or other local changes to the wetland ecosystem is affecting the bird populations. The information collected in this study will provide information to developers and land planners to increase the knowledge of the importance of watersheds and the birds that inhabit them. The data can also influence land planning through-out coastal Maine and New England.