A hierarchical analysis of lek counts: environmental drivers of abundance for an endangered grassland bird

Abstract Populations of Attwater's prairie‐chicken ( Tympanuchus cupido attwateri ), once widespread across the Gulf Coastal Prairies of North America, remain critically endangered. Lek counts of displaying males provide the primary basis for population monitoring, yet these counts are vulnerable to detection error and fail to capture underlying demographic processes. We applied hierarchical Bayesian N‐mixture and Dail–Madsen models to 23 years of lek count data (2002–2024) from Attwater Prairie Chicken National Wildlife Refuge to estimate detection‐adjusted abundance and population trend, and assess relationships between abundance, demographic rates, and responses to environmental drivers. The top‐performing N‐mixture model estimated a mean annual population growth rate of 3% (95% CRI: 1%, 5%), providing statistically supported evidence of a positive trend, whereas the naïve count‐based estimate showed no significant change over time. Dail–Madsen models indicated recruitment, rather than survival, as the primary demographic constraint. Environmental covariates revealed that abundance peaked at intermediate levels of perennial forb and grass cover and under moderate drought conditions, with declines observed under vegetative overgrowth and excessive moisture. The interaction between precipitation and the median time since fire revealed that short median time since fire intervals were associated with greater abundance during normal to wet years, underscoring the importance of frequent prescribed fires (median 2‐ to 3‐year intervals). These results provide the first detection‐corrected trend estimates for this species and offer a model‐based framework for linking weather, vegetation, and fire history with population dynamics. Our findings directly inform adaptive management strategies contributing to recovery for this species and demonstrate how robust analyses of long‐term lek data enhance conservation decision‐making for endangered grassland birds.