MID-ATLANTIC COASTAL PLAIN PHYSIOGRAPHIC AREA: Avifaunal Analysis

The breeding avifauna of the mid-Atlantic Coastal Plain is diverse reflecting the geographic position of the physiographic region and the wide range of available habitats. In many ways, the mid-Atlantic avifauna is transitional containing a mix of species centered in the southeast or the northeast with some additional species spilling over from more inland physiographic regions. More than 25% of the species reach their southern (15.6%) or northern (10.5%) range limit within the physiographic region. These include southern species such as the Brown Pelican, Wilson's Plover, Red-cockaded Woodpecker, and Swainson's Warbler and northern species such as the Short-eared Owl, Bobolink, Swamp Sparrow, and Northern Oriole. An additional 3.3% of the species are associated with the piedmont and mountains but occur in low numbers east of the fall line. The majority (75%) of species breeding within the physiographic region are migratory. These include 79 (43.9%) neotropical migrants and 56 (31.1%) temperate migrants.

Our primary measure of population trends at present is the Breeding Bird Survey (BBS), which provides data on roughly 147 of 180 species breeding within Area-44 (N = 85 routes). However, for many species within this region (particularly those within spatially restricted habitats such as barrier islands and salt marshes) coverage is poor, and reported trends lack statistical significance. Nevertheless, a significant declining trend on existing BBS routes warrants management consideration.

Of the species sampled by BBS, 69 (38.3%) show significant (P < 0.10) population trends. Thirty of these species have declined with 18 declining between 1966 and 1996 and 12 declining between 1980 and 1996. More than 50% of species with a declining trend are associated with early successional grassland/shrubland habitats. Remaining species are associated with forested habitats, wetland, or barrier and bay islands. A total of 39 species showed significant positive population trends with the majority (74.4%) increasing only after 1980. Increasing species include waterbirds and raptors that are recovering from contaminants, species associated with forested habitats, or species that have expanded their geographic ranges.