Winter Distribution of Piping Plovers on the US Gulf of Mexico: An Analysis of Habitat Characteristics at Major Wintering Sites

LeDee, Olivia

Piping Plover (Charadrius melodus) populations have been federally listed as endangered or threatened in the U.S. for 19 years, but recovery efforts have been unable to remove the species from imperiled status. Although most protective efforts focus on plovers while they are on the breeding grounds, greater attention is warranted during the non-breeding period because >75% of the annual cycle occurs during migration and winter; quality and quantity of wintering habitat are known to be important for wintering shorebirds. This study was conducted, at the major wintering sites of Piping Plovers along the U.S. Gulf of Mexico coast, the final destination for most wintering Piping Plovers, to identify key features of the sites that favor or discourage use by plovers. To identify important winter sites for Piping Plovers, I reviewed published records of winter plover surveys to identify important wintering locations and visited a subset of those sites to record habitat features. Piping Plovers consistently winter at 49 locations on the U.S. Gulf of Mexico coast (Marco Island, FL to Padre Island, TX); at 25 locations, Piping Plovers occur in high abundances (>30 individuals). To further understand the landscape features of confirmed wintering sites, I delineated a 3.5km area around Piping Plover observations and conducted a remote analysis of aerial photos for 11 geomorphological (e.g. inter-tidal area, beach area) and human infrastructure (e.g. urban area, roads) characteristics. Linear regressions were used to test correlations between plover abundance and landscape characteristics. I found that Piping Plover abundance was positively correlated with inter-tidal area, inter-tidal and beach area, and peninsula/island landforms. In contrast, plover abundance was negatively correlated with urban are and road length. I used these relationships to parameterize a model that predicts the abundance of Piping Plovers across the Gulf of Mexico coast. The model, incorporating landform category, inter-tidal area, and urban area, explains 46% of the variability in Piping Plover abundance on the entire coast (df=30, adjusted R-squared: 0.4621; p = 0.00018). This study found a relationship between plovers and habitat features demonstrating that both land-formations and urbanization influence the distribution and abundance of Piping Plovers wintering on the U.S. Gulf of Mexico Coast. This information is critical for land managers in the Gulf region as they develop and implement policy in rapidly changing coastal ecosystems.