Date of Award

12-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Wildlife and Fisheries Biology

Committee Member

Dr. Patrick G. R. Jodice, Committee Chair

Committee Member

Ms. Felicia Sanders

Committee Member

Dr. William Bridges

Abstract

Eggs of American horseshoe crabs (Limulus polyphemus) provide migratory shorebirds with an abundant food source at stopover sites, allowing the birds to rapidly gain weight for their migration to arctic breeding sites. Shorebird use of horseshoe crab eggs has been well documented along the Atlantic coast of the U.S. at northeastern stopover sites such as the Delaware Bay. However the relationship between migratory shorebirds and horseshoe crab eggs has not been well studied in South Carolina, where horseshoe crabs are harvested for the biomedical industry. The objective of our study is to determine if there is a correlation between the density of horseshoe crab eggs and the abundance of foraging shorebirds during spring migration at Cape Romain National Wildlife Refuge (NWR). To accomplish this, we monitored 10 - 12 study plots between March and June 2015 - 2016 at predicted horseshoe crab spawning sites throughout the refuge. We conducted weekly shorebird surveys, and surveyed plots twice a month to measure densities of horseshoe crab eggs. We used a linear regression to compare the density of eggs in each plot with the number of foraging shorebirds. Our results show a positive correlation between number of foraging shorebirds and horseshoe crab eggs for both years (t8 = 2.5, r2 = 0.44, P = 0.035; 2015 and t10 = 6.2, r2 = 0.79, P = 0.0001; 2016). We also conducted a dietary analysis of shorebird fecal samples and found that 95% of the fecal samples tested contained horseshoe crab eggs. Our results suggest a correlation between shorebirds and horseshoe crab eggs at the refuge. The results of our study will help provide a better understanding of Cape Romain NWR as a stopover site for shorebirds.

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