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Distribution, abundance, and habitat affinities of the Coastal Plain Swamp Sparrow

Wilson Bulletin

6233_Beadell.pdf
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Abstract

We examined the distribution and abundance of the Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) at previously occupied sites and points within potential habitat. We found Swamp Sparrows throughout their formerly documented range except in southern Chesapeake Bay. Swamp Sparrows were most common in the Mullica River region of New Jersey where we detected individuals at 78% of systematically chosen points with a mean count of 4.1 birds/point. The percentages of points with positive detections in. the regions of Delaware River (39%), eastern Delaware Bay (23%), western Delaware Bay (34%), and Tuckahoe River (31%) were lower. The mean count of birds/point was between 0.4 and 0.6 in these regions. A higher resolution Poisson model of relative abundance suggested that the greatest concentrations of Swamp Sparrows occurred not only in the Mullica River area but also along northwestern Delaware Bay. Regression analysis of Swamp Sparrow counts and habitat features identified shrubs (Iva frutescens and Baccharis halimifolia) as a key habitat component. By applying density estimates generated by DISTANCE (Thomas et al. 1998) to the approximate area of potential shrub habitat along Delaware Bay, we estimated that the core population of Coastal Plain Swamp Sparrows was less than 28,000 pairs. We recommend that the Coastal Plain Swamp Sparrow be listed as a subspecies of concern by state and local governments because of its relatively small population size, restricted distribution in the mid-Atlantic region, and narrow habitat requirements.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Distribution, abundance, and habitat affinities of the Coastal Plain Swamp Sparrow
Series title:
Wilson Bulletin
Volume
115
Issue:
1
Year Published:
2003
Language:
English
Contributing office(s):
Patuxent Wildlife Research Center
Description:
38-44
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
38
Last page:
44
Number of Pages:
7