Songbird Population Dynamics in Fragmented New England Habitat

Project Team: New England Ecological Forecasting Team
Team Location: Goddard Space Flight Center, Greenbelt, Maryland

Sample analysis of deforestation (red) and reforestation (blue) between 2001 and 2011 around a Breeding Bird Survey route (yellow) near Berlin, New Hampshire. Image Credit: New England Ecological Forecasting Team.

Sample analysis of deforestation (red) and reforestation (blue) between 2001 and 2011 around a Breeding Bird Survey route (yellow) near Berlin, New Hampshire. Image Credit: New England Ecological Forecasting Team.

Authors:
Alexander Nelson, Project Lead (Middlebury College)
Sam Weber (Virginia Polytechnic Institute and State University)
Kiersten Newtoff (University of North Carolina, Wilmington)

Mentors/Advisors:
Dr. Morgan Tingley (University of Connecticut and the Institute for Bird Populations)
Dr. Jim Nichols (U.S. Geological Survey Patuxent Wildlife Research Center)
Fritz Policelli (NASA Goddard Space Flight Center)

Abstract:
The majority of songbirds (order Passeriformes) are small perching birds that inhabit terrestrial environments worldwide. They are especially notable for their scientific status as excellent indicators of ecological change, as they interact with a diverse set of organisms in their trophic relationships. Changes in songbird population size and distribution are often indicative of underlying changes in their habitats such as vegetation composition, primary productivity, and climate. Recent trends in decreasing abundance and diversity of songbirds in many areas of North America have been alarming. One potential driver of population change is forest fragmentation, which results in less forest interior habitat and a greater amount of forest edge. This study utilized an occupancy model using songbirds to analyze the effects of various fragmentation metrics. Forest fragmentation metrics were derived using the 2001, 2006, and 2011 National Land Cover Database, Landsat, and Aqua/Terra data from the NASA’s Earth Observing System. The habitat variables were combined with large-scale, multi-year Breeding Bird Survey data from the U.S. Geological Survey. The focal area was Bird Conservation Region (BCR) 14 in the northeastern United States, which is characterized by northern hardwood and spruce-fir forests, a vital transition zone between northern boreal and southern temperate landscapes. Representative species were chosen as models of different life histories and have different theoretical responses to changes in forest structure. The habitat variables and songbird survey data were used in a multi-season occupancy-based model that can be applied to a multitude of avian species across North America. The model predicted the probability that a species will occupy, emigrate, or colonize various habitats given its habitat forest cover, degree of fragmentation, and quality of vegetation. The model was then applied to a sample forested area to determine which habitats would facilitate the occupancy of each focal bird species in this area given current land cover metrics derived from Landsat imagery/data. The National Audubon Society used these model outputs to facilitate its conservation work to enhance management actions on a landscape scale. These products also helped to provide a strong foundation for the future of songbirds and their habitats in North America.

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