Science1 publisher2 min readPublished
Shifting UK mowing and grazing dates by two to three weeks would cover far more wader nests
Nesting records from across the UK show that scheme exclusion dates, set one per country, miss when lapwing and oystercatcher are actually on eggs, and an Aberdeen-led team puts the fix at two or three weeks.
The Scientist · Science desk
What happened
- Researchers at the University of Aberdeen and Edinburgh Napier University compared UK wader nesting records with the dates agri-environment schemes use to delay mowing and grazing, and published the work in the Journal of Applied Ecology.
- Scotland's breeding numbers fell 63% for lapwing, 62% for curlew and 41% for oystercatcher between 1995 and 2024, over a period in which grass was cut earlier and more often.
- Scheme exclusion dates are generally applied uniformly across each UK country, and the nesting data show breeding seasons varying enough between species and areas that protection is often mistimed.
- Retiming those dates, in some cases by as little as two to three weeks, would raise protection of nests from livestock by 30% for lapwing and 57% for oystercatcher.
- Protection of chicks from mowing operations would rise by 35% for lapwing and 72% for oystercatcher under dates tailored to species and location.
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Why it matters
- decision NatureScot can act on this within the options the scheme already funds. The question in front of it is which dates those options carry, and dates can be amended without designing a new payment.
- constraint A date change reaches only the nests and chicks lost to machinery and livestock. Predation and habitat degradation continue regardless, and Gray places both in the harder-to-mitigate category.
- capability Because the nesting datasets are UK-wide, exclusion dates can be specified by species and by area instead of one line per country, which was not possible without that evidence base.
- precedent Scotland's scheme is the target of this work, but uniform dates are the norm across the UK, so the same recalibration is now available to the other national schemes on the same data.
A single national date has to stand in for every wader nest in the country. The nesting records behind the study, which include datasets from the British Trust for Ornithology, the Royal Society for the Protection of Birds and the Game & Wildlife Conservation Trust, show breeding seasons varying considerably between species and between areas [8]. Leah Gray, the University of Aberdeen postgraduate researcher who led the work, said, "Our research shows that current agricultural exclusion dates are often missing the periods when birds are actually nesting and raising chicks." [14][15]
The correction lands unevenly. Moving the dates raises protection of nests from livestock by 30% for lapwing and 57% for oystercatcher, and protection of chicks from mowing by 35% and 72% [10][11]. On both measures the oystercatcher gain is close to double the lapwing one: 1.9 times on nests, 2.1 times on chicks [20]. Oystercatcher is also the species of the three that has held up best, down 41% in Scotland since 1995 against 62% for curlew and 63% for lapwing [4][21]. Twenty-nine years of decline leaves Scotland's lapwings at about 37% of their 1995 number [18][19].
These are percentage increases in protection from machinery and livestock, not counted fledglings. The release does not state the baseline they improve on, so a 30% increase cannot be turned into a number of nests. The published figures cover lapwing and oystercatcher [22].
That distinction matters because the population problem sits one step further down the chain. Gray said, "The main driver of wader population declines is a widespread decrease in breeding success. In recent decades, waders have simply not been able to produce enough fledglings to sustain their populations." [12] She also ranked the pressures: "While many of these pressures need to be addressed, agricultural losses are comparatively simpler to mitigate compared to more complex issues such as predation and habitat loss." [17] On the same reasoning she said that "Changes to livestock management and mowing regimes therefore offer an 'easy win' for conservation and are among the most effective interventions for supporting breeding waders." [13]
The work was done to give NatureScot, which advises the Scottish Government on Scotland's agri-environment scheme, evidence it can use directly [16]. The scheme already pays farmers to hold off mowing and to keep livestock out until later in the breeding season [6]. The paper proposes moving the dates attached to those payments, in some cases by as little as two to three weeks [9].
What to watch
- Whether NatureScot's next revision of Scotland's agri-environment scheme carries species- and region-specific exclusion dates.
- A field test that counts fledged chicks on land under the old and the proposed dates, rather than exposure windows alone.
- Whether the paper's curlew analysis points the same way as its lapwing and oystercatcher results.