Piping Plover (Charadrius melodus) habitat selection, survival, and migration on New York barrier islands following natural and engineered habitat changes

Abstract

The piping plover (Charadrius melodus) is an imperiled migratory shorebird that nests on mainland and barrier island beaches on the Atlantic coast of North America. Its population decline was attributed to habitat loss, predation, coastal development, and disturbance. Hurricane Sandy reached the Northeast United States in October, 2012. The storm breached and overwashed two barrier islands of New York that support breeding piping plovers, Fire Island and Westhampton Island. In response to geomorphic island changes, the U.S. Army Corps of Engineers stabilized the islands by filling breaches, building dunes, and nourishing beaches. In accordance with the U.S. Fish and Wildlife Service and the Endangered Species Act, the U.S. Army Corps of Engineers constructed piping plover nesting habitat to mitigate the loss of habitat from engineering. The objectives of this study were to assess habitat selection and quantify suitable habitat before and after Hurricane Sandy and to investigate survival and migration of fledgling piping plovers within their first year. We studied piping plover nest-site selection, habitat, and abundance before (2010) and after (2015) Hurricane Sandy and engineered response. Before the storm, piping plovers selected nest sites (n=62) farther from the ocean (x̄ least-cost distance = 82.8 m) and bay (x̄ Euclidean distance = 697.7 m; x̄ least-cost distance = 24,160.6 m) than would be expected if they were selecting nest sites at random. Following the storm, piping plovers selected nest sites (n=45) that were close to, and had unobstructed walking access to, the ocean (x̄ least-cost distance = 123.4 m) and newly-created bayside foraging habitats (x̄ Euclidean distance = 468.0 m; x̄ least-cost distance = 728.9 m). Areas overwashed by the hurricane contained the most suitable piping plover habitat across all new habitat types. Piping plover abundance increased 93% by 2018 from pre-Hurricane Sandy abundances, with most pairs nesting in new habitats. However, only 58% of suitable piping plover habitat was protected from recreational use and only 4% of piping plovers used unprotected habitats for nesting during 2015–2017. We assessed post-fledging survival with radio telemetry and mark-recapture methods. We banded and monitored 292 fledged chicks from 2013–2018. We affixed nanotags to 43 pre-fledged chicks and tracked them to document mortality on their natal grounds. We used a multi-state open robust design model to estimate post-fledging survival within the first year and migration and return probabilities. Daily survival rate as estimated with nanotags was the same as estimated with mark-recapture methods (0.997). Post-fledging survival did not vary in the six years following the storm, nor did it vary across stages within an individual's first year (0.36; 95% CI = 0.31–0.42). Fledgling migration occurred between July 1 and September 22 and reached its peak between August 15–23 (Ψ = 0.97, 95% CI: 0.92–0.98). Individuals with earlier fledge dates migrated earlier (β = ˗1.51, 95% CI: ˗1.11–˗1.91). Second-year plovers returned to the breeding grounds between February 20 and May 8, with a peak occurring in late April and early May (Ψ = 0.55, 95% CI: 0.41–0.70). Given that newly-created storm and engineered habitats benefitted nesting and brooding plovers, ensuring protection of these and other suitable habitats would likely safeguard fledglings that persist on Fire Island for more than a month before departure.