Do diets vary over large spatial or temporal ranges? A test using interannual and interpopulation data on Diamondback Terrapin (Malaclemys terrapin) diets

Abstract

Animal diets may vary spatially or temporally as resource availability vary. Diets of species with extensive geographic ranges often span multiple habitats, thus their diets may vary accordingly. Temporal diet variation is rarely explored because most diet studies are short term; this is problematic for long-lived species where individuals may persist as prey availability changes. We analyzed diet variation in Diamondback Terrapins (Malaclemys terrapin (Schoepf, 1793)), which inhabits nearly 70 000 km of United States Atlantic coastline, spanning 16.5°N latitude and 27.4°W longitude and four Köppen climatic zones, and Bermuda. We explored spatially or temporally Diamondback Terrapin diet variation, including populations from Atlantic salt marshes, an Everglades mangrove swamp, the Texas Gulf Coast, and a Caribbean golf course pond. We found remarkably high levels of similarity, indicating that although diets vary according to local prey availability, they are broadly similar at lower taxonomic resolution. Even short-term studies may be sufficient to accurately characterize diets of Diamondback Terrapins. These results are surprising given the geographic range sampled in this study and indicate that Diamondback Terrapin diets are conservative, reflecting local prey availability. Such diets apparently allow Diamondback Terrapins to exploit their extensive range and may allow Diamondback terrapin populations to persist as local prey species wax and wane.