Restoring Beaches for Atlantic Coast Piping Plovers (Charadrius melodus): A Classification and Regression Tree Analysis of Nest-Site Selection

To effectively restore wildlife habitat, ecological research must be easily translated into practical design criteria. Clear directives from research can support arguments that promote more appropriate restoration strategies. For the federally threatened piping plover (Charadrius melodus), beach stabilization practices often accelerate the degradation of suitable breeding habitat and could be revised to provide more advantageous conditions. Several studies of piping plover habitat selection have been conducted, yet useful and detailed design directives remain undeveloped. In this study, we use classification and regression tree analysis to (1) identify microhabitat characteristics and important variable interactions leading to nest establishment and (2) develop target, trigger, and threshold values for use in effective design and adaptive management of piping plover habitat. We found that nests primarily occur in three distinct habitat conditions defined by percent shell and pebble cover, vegetative cover, and distance to nearest dunes and the high tide line. Nest-site characteristics vary depending on where in the landscape a nest is initiated (backshore, overwash fan, or primary dune). We translate these results into the following pragmatic target design parameters: (1) vegetative cover: less than 10% (backshore), 13% (primary dune); (2) shell/pebble cover: 17-18%; (3) dune height: < 1.1 m; and (4) dune slope: < 13%. We also recommend threshold values for adaptive management to maintain habitat that is attractive to plovers. This technique can be applied to many other wildlife habitat restorations. Future studies on niche parameters driving chick survival are necessary to realize the full potential of habitat restoration in increasing overall reproductive success.