The Mississippi Coastal Improvement Program (MsCIP) Monitoring and Adaptive Management Program (MAMP) notes that five sea turtle species are found in the northern Gulf of Mexico, including loggerhead, green, Kemp’s ridley, leatherback, and hawksbill. Green, loggerhead, and Kemp’s ridley sea turtles are regularly documented in the waters surrounding the barrier islands of Gulf Islands National Seashore. Of these, only loggerhead sea turtles have been confirmed as nesting on the islands in the Mississippi Sound and they are the only species with designated critical habitat within the island chain (Horn and Petit Bois Islands). Green sea turtle nests have been found on the Mississippi islands; however, these nests are likely uncommon. Though never documented, Kemp’s ridley sea turtles could nest on the islands. Leatherback and hawksbill sea turtles may be seen in the barrier island waters, but there are no confirmed nest records within the barrier island project area. A subtask of the MsCIP MAMP is to identify potential sea turtle nesting habitat on Cat and Ship Islands. This objective was achieved using digital elevation models (DEMs) developed using light detection and ranging (lidar) data and dune toes from lidar-derived beach morphology (Doran and others, 2020). Island tips will be added to the nesting area by using a combination of photointerpretation and habitat data to determine the mean high water line based on water regime. References: Doran, K.S., Long, J.W., Birchler, J.J., Brenner, O.T., Hardy, M.W., Morgan, K.L.M, Stockdon, H.F., and Torres, M.L., 2017, Lidar-derived beach morphology (dune crest, dune toe, and shoreline) for U.S. sandy coastlines (ver. 4.0, October 2020): U.S. Geological Survey data release, https://doi.org/10.5066/F7GF0S0Z.