Abstract Farmland birds have declined by approximately 60% in Europe, with the proportion of endangered species exceeding that in any other habitat guild. Agricultural intensification, characterized by larger fields, increased pesticide use, and reduced crop and structural diversity, is a primary driver of these declines. Although conservation measures have been implemented, population trends remain negative, largely due to limitations in their effectiveness and implementation, while remaining knowledge gaps regarding habitat selection and breeding success may further constrain conservation outcomes. Using a 12‐year field study of the critically endangered ortolan bunting ( Emberiza hortulana ) in Germany, we demonstrate strong interannual variation in crop type preferences and avoidance. Winter rye, spring barley, and grain legumes were consistently preferred with mean effect size (Hedges' g values) above 0.1, whereas winter barley, sugar beet, oilseed rape, and grassland were consistently avoided (Hedges' g below −0.1). This pattern suggests that birds choose territories mainly based on vegetation structure rather than the specific crop type. Moreover, breeding territories were strongly associated with well‐drained soils with low soil fertility (values <35). In the study area, many crops such as potato are intensely irrigated to maintain agricultural yield despite good drainage. We argue that such irrigation may increase clutch and nestling mortality for ground‐nesting farmland birds such as the ortolan bunting under predicted climate warming. Our results emphasize the need for conservation management strategies that prioritize structural diversity and promote non‐irrigated crops or more targeted drip‐irrigation to support the recovery of the ortolan bunting and potentially other ground‐nesting farmland birds with similar habitat requirements.
Jensen et al. (Mon,) studied this question.