Coastal bird community response to dredge‐spoil tidal marsh restoration at New Round Island, Mississippi, U.S.A.

Abstract

The northern Gulf of Mexico has been the focus of many coastal habitat restoration projects in the wake of new funding streams stemming from the settlement of the 2010 Deepwater Horizon oil spill litigation. One such project was the creation of New Round Island (RNDI) in Mississippi, a 86 ha island created using dredge material in 2017. The island design incorporated a novel U‐shaped sand berm with multiple interconnected containment sells. In this study we sought to document changes in relative abundance of various coastal bird species. We conducted surveys for breeding and nonbreeding birds from June 2017 to May 2021, and we conducted nonbreeding surveys at two reference sites for comparison. Breeding bird numbers were dominated by colonial nesting species in years 1 and 2, which subsequently declined as vegetation cover increased. Solitary nesting species increased over time, with Wilson's Plover (Charadrius wilsonia) nest count increasing from zero in year 1 to 29 in year 5. Nonbreeding shorebird counts peaked in years 1–2 and subsequently declined, although shorebird counts also decreased at the reference sites. Relative abundance of waders (Ardeidae), rallids (Rallidae), and passerines (Passeriformes and allies) increased in comparison to reference sites. This study demonstrates the short‐term benefits of this U‐shaped island design to early‐succession breeding species and nonbreeding shorebirds shortly after construction, with longer‐term benefits to breeding Wilson's Plover and to marsh birds as vegetation fills in.