The man-made beaches of Harrison County, Mississippi, are an important area for breeding Least Terns, hosting the densest population in the northern Gulf. This area has historically held up to 6,300 breeding pairs, though this number has declined in recent decades. Despite a robust stewardship program initiated by National Audubon Society in 2014 aimed at protected breeding Least Terns from disturbance, populations have continued to decline since 2020. As of 2025, Least Terns had declined 61% since a peak of 1,918 pairs in 2020, and have declined by 47% since 2017. Identifying the causes of this decline will be critical to prioritizing management actions needed to halt or reverse this trend. There are multiple factors that likely contributed during this time frame, including habitat loss due to beach erosion, storm events resulting in colony overwash during peak breeding periods, and increases in predator pressure. Habitat availability has declined by 26% since 2017, with most of the beach loss occurring between 2023 and 2024. Low breeding productivity (<0.40 fledglings/pair) has been documented in seven of the last nine years, with no or negligible productivity in the three years in which Mississippi was hit by tropical cyclones in June. Population modeling will be the next step in order to assess the relative importance of habitat loss and low productivity to the observed population decline.  This will allow conservation practitioners to predict the effectiveness of new habitat creation versus predation management of existing habitat in conserving the mainland Mississippi Least Tern population.