Status, Distribution, and Habitat Use of Coastal Waterbirds Along the Mississippi Gulf Coast, USA

The northern Gulf of Mexico is an important stopover and wintering area for many coastal waterbird species, but this region has been little-studied and a paucity of data has hampered efforts to quantify damage caused by disasters such as hurricanes and oil spills. In response, the Audubon Coastal Bird Survey (ACBS) was established to fill this data gap and provide long-term monitoring of coastal birds in this region. This study uses three years of data (2014-2017) from 22 1.6-km transects to identify areas in Mississippi, USA that are important to coastal waterbirds, to compare relative abundance of 14 focal species to abundances prior to the Deepwater Horizon oil spill, estimated using eBird data, and to compare the information gained using ACBS to that of eBird. Shorebirds (Haematopodidae, Recurvirostridae, Charadriidae, and Scolopacidae) were most abundant at barrier island sites; larids (Laridae) were most abundant on man-made mainland beaches; and waders (Ardeidae) were most abundant at vegetated nearshore islands and natural mainland sites. Relative abundances of Least Tern (Sternula antillarum) and Brown Pelican (Pelecanus occidentalis) increased post-spill, while Piping Plover (Charadrius melodus) and Wilson's Plover (C. wilsonia) decreased. Relative abundances estimated using ACBS vs. eBird were greater for seven focal species, particularly for smaller shorebird species. Received 3 January 2020, accepted 15 October 2020.