Western Snowy Plover nest site characteristics differ from available habitat and can be assessed in the post-breeding season

The Pacific coast population of the Western Snowy Plover Anarhynchus nivosus nivosus is vulnerable to the loss of the dune and sandy beach habitats used by this threatened shorebird. Preservation and restoration of coastal nesting habitat is fundamental to recovery of the species and requires a detailed understanding of nest-site habitat preferences. Sandy coastlines are dynamic systems, limiting the timeframe in which habitat measurements reflect the characteristics plovers select when initiating a nest. However, the most relevant timeframe for data collection is also when plovers are most sensitive to disturbance: during the breeding season. We surveyed habitat at plover nest sites and nearest random points during the breeding season and the fall immediately post-breeding to examine nest-site microhabitat selection and to determine whether post-breeding habitat measurements are still representative of breeding season habitat. We found that plovers select nest sites based on overall microhabitat characteristics rather than specific plant species. Across seasons, nest sites were significantly more likely to have adjacent objects (vegetative or inanimate). Nests tended to be located where cover of pioneer stabilizers, a dune plant functional group that includes Beach Bur Sage Ambrosia chamissonis, was ~10%, and where pioneer builders, another group which includes Sea Rocket Cakile maritima, American Dune Grass Leymus mollis, and Beach Saltbush Atriplex leucophylla, were present at less than 5 or 10% cover, depending on the presence and type of the adjacent object. Seasonal differences were minimal, suggesting that fall habitat may still be representative of breeding season habitat. Based on these findings, we make recommendations for approaches that could be applicable across the range of the Pacific coast population and encourage delaying habitat assessments until the breeding season concludes. Our research helps bridge the gap between scientific findings and practical implementation of habitat monitoring and management of the Western Snowy Plover.