Liben Lark Heteromirafra archeri is a ‘Critically Endangered’ species threatened by the loss and degradation of grassland at the Liben Plain, southern Ethiopia, one of only two known sites for the species. We use field data from nine visits between 2007 and 2019 and satellite imagery to quantify changes over time in the species’ abundance and in the extent and quality of its habitat. We estimate that the population fell from around 279 singing males (95% CL: 182–436) in 2007 to around 51 (14–144) in 2013, after which too few birds were recorded to estimate population size. Arable cultivation first appeared on the plain in the early 1990s and by 2019 more than a third of the plain had been converted to crops. Cultivation was initially confined to the fertile black soils but from 2008 began to spread into the less fertile red soils that cover most of the plain. Liben Larks strongly avoided areas with extensive bare ground or trees and bushes, but the extent of these did not change significantly over the survey period. A plausible explanation for the species’ decline is that grassland degradation, caused before 2007 by continuous high-pressure grazing by livestock, reduced its rates of reproduction or survival to a level that could not support its previous population. Since 2015, communal kalos (grazing exclosures) have been established to generate forage and other resources in the hope of also providing breeding habitat for Liben Larks. Grass height and density within four grassland kalos in 2018 greatly exceeded that in the surrounding grassland, indicating that the plain retains the potential to recover rapidly if appropriately managed. Improvement of grassland structure through the restitution of traditional and sustainable rangeland management regimes and the reversion of cereal agriculture to grassland are urgently needed to avert the species’ extinction.

Liben Lark Heteromirafra archeri是一种“极度濒危”物种，受到埃塞俄比亚南部利本平原草原丧失和退化的威胁，这是该物种仅有的两个已知地点之一。我们使用 2007 年至 2019 年 9 次访问的实地数据和卫星图像来量化该物种的丰度及其栖息地的范围和质量随时间的变化。我们估计，种群数量从 2007 年的约 279 只歌唱雄性（95% CL：182-436）下降到 2013 年的约 51 只（14-144），之后记录的鸟类太少，无法估计种群规模。耕地最早出现在 1990 年代初期的平原上，到 2019 年，超过三分之一的平原已转为农作物。种植最初仅限于肥沃的黑土，但从 2008 年开始扩展到覆盖大部分平原的不太肥沃的红土。Liben Larks 强烈避开大面积裸露地面或树木和灌木丛的区域，但在调查期间，这些区域的范围没有显着变化。对该物种衰退的一个合理解释是，在 2007 年之前，由于牲畜持续高压放牧造成的草原退化，使其繁殖率或存活率降低到无法支持其先前种群的水平。自 2015 年以来，公共已经建立了kalos （放牧围栏）以产生草料和其他资源，希望也为 Liben Larks 提供繁殖栖息地。2018年4个草原的草高和密度大大超过周边草原，表明如果管理得当，平原仍具有快速恢复的潜力。迫切需要通过恢复传统和可持续的牧场管理制度以及将谷物农业恢复为草地来改善草地结构，以避免该物种的灭绝。