Farmland ecosystems are seasonally dynamic habitats shaped by meteorological fluctuations and anthropogenic land-use changes. Farmland birds may be seasonally constrained with limited foraging and breeding resources (so-called “resource bottlenecks”), especially when there is a loss of natural and semi-natural habitats. During spring, the growth of cereal crops makes a large proportion of arable land unsuitable for specialist steppe birds with narrow vegetation structure requirements. We investigated the existence of a seasonal bottleneck of suitable habitats for steppe birds using the endangered Pin-tailed sandgrouse (Pterocles alchata) as a model species. We used for first time lightweight GPS tags to study habitat selection and movement patterns throughout the cereal crop cycle during three years in north-eastern Spain. We also evaluated if conservation measures promoting suitable vegetation structures for steppe birds (Targeted Fallow Management, TFM) influenced habitat selection. Sandgrouse avoided cereal crops when cereal vegetation was high, resulting in a 30% reduction of suitable habitat area at the start of the breeding season. This proved the existence of a spring habitat bottleneck when sandgrouse only selected open natural habitats and fallows. Sandgrouse similarly selected TFM and conventionally managed fallows during and after the bottleneck, possibly because of their similar vegetation structure and the scarcity of alternative suitable habitats. Halting the ongoing loss of fallow land is paramount for the conservation of steppe birds like sandgrouse because they constitute a key refuge to buffer the impacts of seasonal habitat bottlenecks.

农田生态系统是由气象波动和人为土地利用变化形成的季节性动态栖息地。由于觅食和繁殖资源有限（所谓的“资源瓶颈”），农田鸟类可能会受到季节性限制，尤其是在自然和半自然栖息地丧失的情况下。在春季，谷类作物的生长使得大部分耕地不适合具有狭窄植被结构要求的专业草原鸟类。我们使用濒临灭绝的针尾沙鸡 ( Pterocles alchata ) 调查了草原鸟类适宜栖息地的季节性瓶颈。) 作为模式物种。我们首次使用轻型 GPS 标签来研究西班牙东北部三年期间整个谷物作物周期的栖息地选择和移动模式。我们还评估了促进草原鸟类适宜植被结构的保护措施（目标休耕管理，TFM）是否影响栖息地选择。沙鸡在谷类植被高时避开谷类作物，导致繁殖季节开始时适宜栖息地面积减少 30%。当沙鸡只选择开放的自然栖息地和休耕地时，这证明了春季栖息地瓶颈的存在。Sandgrouse 在瓶颈期间和之后同样选择了 TFM 和常规管理的休耕地，这可能是因为它们相似的植被结构和替代合适栖息地的稀缺性。