This study examined whether Diamondback terrapin eggs provide a source of nitrogen to American beach grass plants growing near terrapin nests. Stable nitrogen isotope ratios were measured in beach grass from sites with and without terrapin nesting in the Gateway National Recreation Area. The results showed higher nitrogen isotope ratios in plants from sites without nesting compared to those with nesting, suggesting terrapin eggs do not transport nutrients from marine to dune ecosystems. However, the presence of more seagulls and guano at non-nesting sites may have impacted the results. Future studies could help isolate the effects of terrapin nests by controlling for external nitrogen sources.