Structurally complex marshes support breeding Laterallus jamaicensis jamaicensis (Eastern Black Rail) occupancy

Abstract Laterallus jamaicensis jamaicensis (Eastern Black Rail) is a federally threatened, rare, cryptic species whose habitat requirements across the U.S. Gulf Coast remain poorly understood, limiting effective conservation planning and implementation. To enhance our understanding of L. j. jamaicensis ecology, we examined the relationship between L. j. jamaicensis occupancy and vegetation structure, plant diversity and community composition, and topography. We conducted 2,524 call-broadcast surveys at 281 sites across 25 properties in the U.S. Gulf Coast (coastal Texas, Louisiana, and Florida). Surveys occurred in high marsh and adjacent wetlands (e.g., estuarine marsh) during the L. j. jamaicensis breeding season (March–August) in 2022 and 2023 and were paired with annual vegetation surveys. Using stacked single-season occupancy models, we assessed relationships among occupancy, detection covariates, and site-specific characteristics. Detection was highest at warmer temperatures, under low wind conditions, and closer to a new moon. Laterallus j. jamaicensis occupied 34% of survey sites, with a predicted detectability of 43%. Laterallus j. jamaicensis occupancy was associated with dense canopy cover (>68% mean herbaceous canopy cover), an open, heterogeneous sub-canopy (<48% mean ground stem cover with >15 percentage points of variation), and a heterogeneous surface organic layer (>6 cm of variation in depth). Occupied sites also had consistently short vegetation (16–56 cm visual obstruction height with <23 cm of variation). We observed little to no evidence of consistent differences in vegetation species composition between occupied and unoccupied sites. Together, these results indicate that L. j. jamaicensis exhibits consistent structural habitat associations in the study area, despite regional differences in plant communities. These findings underscore the value of structurally complex marshes for L. j. jamaicensis populations and provide a foundation for improved monitoring and conservation efforts across the U.S. Gulf Coast.