Factors Affecting Prey Availability and Habitat Usage of Wintering Piping Plovers (Charadrius melodus) in Coastal Louisiana

• Main Author: Schulz, Jessica L.
• Format: Thesis
• Language: English
• Published: University of Louisiana at Lafayette 2015
• Subjects: Ecology; Barrier Island; Barrier Islands; Trinity Island
• Online Access: http://pqdtopen.proquest.com/#viewpdf?dispub=10002450

The Gulf of Mexico is home to a large proportion of the wintering population of the threatened piping plover, but little is known about the bird’s ecology in this region. In Louisiana, the majority of wintering piping plovers are found on the state’s rapidly eroding barrier islands. Between August 2013 and May 2014, we conducted shorebird surveys to assess the abundance and habitat use patterns of piping plovers on a barrier island refuge in south central Louisiana. Seventy-five percent of piping plovers observed were foraging, mostly (92%) in the intertidal zone; 20% were roosting in more diverse microhabitats. To characterize the prey base for piping plovers on the islands, we collected core samples in the intertidal zone of two islands on the refuge. The invertebrate community was dominated by haustoriid amphipods, which comprised 87.5% of individuals collected. Bivalves and polychaetes accounted for 9.3%, and 2.7%, respectively. We used generalized linear models to evaluate the effects of environmental predictors on amphipod abundance and odds of bivalve and polychaete presence at the sample site scale, and also on piping plover densities at the transect scale. Moisture had a positive effect on amphipod abundance and polychaete presence. Seasonal patterns and between-island differences were observed in all three taxa, but these effects differed between main beach habitat and the gulf- and bay-sides of prominent sand spits. Amphipod densities and piping plover densities were correlated on Trinity Island and during spring 2014, but prey abundance did not differ between sample sites where piping plovers were foraging versus random sites. Uncertainty in the degree to which piping plover distributions in Louisiana are driven by prey abundance is of concern because the extensive beach nourishment programs being implemented to stave off coastal land loss may have potentially substantial impacts to benthic invertebrates and their predators.