The Sierra Madre Sparrow Xenospiza baileyi is an endangered Mexican endemic and a bunchgrassland specialist with a disjunct range: a relatively larger population in the south-eastern Trans-Mexican Volcanic Belt, and a smaller and poorly studied population in the Sierra Madre Occidental. In the latter, known distribution and abundance consists of four localities with a maximum of 28 individuals recorded in one of them. We surveyed the Sierra Madre Sparrow in 30 sites with suitable habitat, meadows or “bajíos” with bunchgrasses, in the municipalities of Durango, Pueblo Nuevo, San Dimas, and Canatlán in the Sierra Madre Occidental of Durango. We detected a total of 193 individuals in nine (30%) of the sites (392 ha), conducting intensive searches throughout them. Bunchgrasses in confirmed meadows were composed mainly of Muhlenbergia macroura, M. rigida, M. speciosa, M. rigens, and Piptochaetium fimbriatum. Total bunchgrass area within a meadow was a significant positive predictor of the Sierra Madre Sparrow presence, while total meadow area was not a significant predictor of its abundance. Seven of the confirmed localities were previously unknown, and two of them harboured 55% of the observed individuals: Ex Hacienda Coyotes (Pueblo Nuevo) and La Lobera (San Dimas). The estimated population size is at least four times higher than any previous record (28) or suggested (40–50) for the Sierra Madre Occidental and raises an opportunity and a challenge for conserving this genetically distinct population of the Sierra Madre Sparrow in the region.

马德雷山脉麻雀Xenospiza baileyi是一种濒临灭绝的墨西哥特有种，也是丛生草地专家，分布范围不连续：在跨墨西哥火山带东南部的种群数量相对较多，而在西马德雷山脉的种群数量较少且研究不足。在后者中，已知的分布和丰度包括四个地点，其中一个地点最多记录了 28 只个体。我们在杜兰戈西马德雷山脉的杜兰戈、新普韦布洛、圣迪马斯和卡纳特兰等市的 30 个具有合适栖息地、草地或长有束草的“bajíos”的地点对马德雷麻雀进行了调查。我们在其中 9 个地点（392 公顷）中总共发现了 193 只个体，并对这些地点进行了密集搜索。已确认草甸的束草主要由大花木兰组成，M.rigida、M.speciosa、M.rigens和Piptochaetium fimbriatum。草地内的束草总面积是马德雷山脉麻雀存在的显着正向预测因子，而草地总面积并不是其丰富度的显着预测因子。已确认的地点中有七个以前未知，其中两个地点藏有 55% 的观察到的个体：Ex Hacienda Coyotes（新普韦布洛）和 La Lobera（圣迪马斯）。估计的西马德雷麻雀种群数量至少是以往任何记录 (28) 或建议 (40-50) 的四倍，这为保护该地区马德雷山脉麻雀这一遗传独特的种群带来了机遇和挑战。