Timing matters for farmland breeding waders: Aligning agri‐environment exclusion periods with species‐ and latitude‐specific nesting phenology

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Abstract A common intervention in agri‐environment schemes is the exclusion of farming activities during sensitive life stages of target species, for example, the exclusion of mowing or grazing to reduce nest and chick losses in ground‐nesting birds. To be effective, the timing of exclusion periods must accurately align with species phenology; however, most schemes apply nationally fixed dates that overlook phenological variation. We quantified trends in wader nesting phenology across the United Kingdom (over ~1200 km of latitude), using 50 years of nesting data for the declining northern lapwing Vanellus vanellus ( n = 6277) and Eurasian oystercatcher Haematopus ostralegus ( n = 2387). The timing of nesting differed significantly between species, with up to 6 weeks separating the start of nesting in lapwing and oystercatcher. The timing of nesting also varied with latitude, with lapwing nesting later at higher latitudes and oystercatcher earlier, shifting by up to 3 days per 100 km. These patterns mean current agri‐environment scheme interventions are misaligned with true breeding phenology. In our case study of Scotland, in an average year, on agri‐environment scheme land, up to 80% of lapwing and 84% of oystercatcher pairs are still nesting on the date of permitted livestock introduction, risking disturbance and trampling. In silage fields, up to 35% of lapwing and 72% of oystercatcher chicks are <20 days old on the permitted mowing date, risking mortality from machinery. Relatively minor adjustments to current timelines could substantially improve breeding outcomes. Adjusting exclusion dates with latitude and target species, and extending current dates by approximately 2 weeks, is predicted to reduce nest exposure to livestock to 50% for lapwing and 27% for oystercatcher and could eliminate mowing exposure for <20‐day‐old chicks in both species. Synthesis and applications: We propose an evidence‐based system that prescribes context‐specific exclusion dates based on three simple criteria: target species, latitude and agricultural activity. This framework would allow policy to account for complex phenological variation, significantly improving breeding outcomes, while remaining administratively manageable and scalable. It is essential to maximise the effectiveness of these interventions to ensure that substantial public investment translates into meaningful conservation outcomes.

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