The Curlew Evidence Defra Asked For
Quick summary
The UK holds around a quarter of the world's breeding Eurasian curlew, more than any country except Finland and Russia.
UK breeding curlew fell 49% on the Breeding Bird Survey between 1995 and 2021. In Wales the fall is 74%, among the three steepest of any Welsh breeding bird.
Paired-site research recorded 1.05 fledglings per pair on keepered grouse moor against 0.27 on comparable ground without predator control — almost four times as many.
A population needs 0.5 to 0.6 fledglings per pair to hold steady. Most studied populations fall below it.
One in four of the world's breeding curlew nest in these islands. Only Finland and Russia hold more, and research in Ecology and Evolution puts the UK's share of the EU breeding population at roughly 60%, with moorland holding much of the UK total. Losses here cut the global total.
Defra's Call for Evidence on gamebird release, shooting and welfare closes on 1 November. It asks directly about effects on Red List species. Curlew has been on the UK Red List since 2015 and is Near Threatened on the IUCN list globally.
Why this evidence belongs in a gamebird submission
Red grouse are wild. They are not reared and not released, which is worth stating plainly to Defra in its own right. But the keepering that produces the results below — the lethal predator control, the year-round staff, the estate budgets that pay for both — exists because driven grouse shooting pays for it.
Policy that alters the viability of shooting alters the predator control. Defra should see the curlew figures before it sets that policy.
The scale of the loss
The JNCC published its Official Statistic on UK breeding bird trends in April 2026, drawing on the BTO/JNCC/RSPB Breeding Bird Survey. Across the UK, breeding curlew fell 49% between 1995 and 2021 on the same survey.
The decline is steepest in Wales, at 74% since 1995 — one of the three worst of any Welsh breeding bird, alongside swift (-76%) and yellowhammer (-75%).
The range has contracted as well as the population. Curlew once bred across lowland farmland and wet grassland. It is now scarce there, and what remains is concentrated in the uplands.
The problem is chicks, not adults
Adult curlew are long-lived. A pair can return to the same field for a decade. What has failed is productivity: too few chicks reach fledging to replace the adults that die.
Grant and colleagues put the replacement threshold at 0.5 to 0.6 fledglings per pair per year. Reviews of European studies find most measured populations fall below it.
What the paired-site study found
A 2023 study in the European Journal of Wildlife Research tested the question directly. Researchers examined 18 moorland-farmland blocks across several UK regions. Each block paired a site where gamekeepers carried out lethal predator control on moorland managed for red grouse with a nearby site on similar habitat where predators were not controlled.
The results:
Curlew productivity of 1.05 fledglings per pair on the keepered sites against 0.27 on the unkeepered sites.
Roughly double the wader density on the keepered sites, and more wader species.
A combined index of corvids and fox three- to fourfold lower where control was carried out.
Fewer eggs hatched and fewer chicks fledged where that predator index was higher. Eleven habitat variables and two grazing variables were tested alongside it and made no difference.
The keepered sites were fledging chicks at roughly twice the replacement rate. Their paired sites were at half of it.
What three other datasets show
A 2014 paper in the Journal of Applied Ecology, authored in part by RSPB and BTO researchers, found curlew population change over eight to ten years was positively related to gamekeeper density and inversely related to surrounding woodland area.
Nesting success followed the same pattern, which points to nest predation as the mechanism.
The same paper produced a figure that relates directly on tree planting. Its models predicted that raising woodland cover from 0% to 10% within 1 km of an occupied site would require a 48% increase in predator control effort — a level associated with high-intensity grouse production — merely to hold curlew numbers level.
An eight-year field experiment in Northumberland, published in the same journal in 2010, held habitat constant and manipulated predators instead. Fox abundance fell 43%. Breeding success of curlew, lapwing and golden plover approximately tripled.
A separate survey of 104 km² across 18 northern estates found predator control the strongest single predictor of curlew abundance among all variables tested.
What the four studies agree on
The four studies used four different methods and reached the same conclusion. The 2023 paired-site work compared neighbouring ground and found a fourfold productivity gap.
The 2014 analysis tracked population change against gamekeeper density across years and sites.
The 18-estate survey ranked predator control above every other variable it tested.
And the Northumberland experiment kept the habitat constant, cut fox abundance by 43%, and roughly tripled wader breeding success. It is the only one of the four designs that can separate cause from correlation.
Where predators are controlled, curlew fledge chicks above 0.5 to 0.6 per pair. Where they are not, curlew fledge chicks below it.
Very little of England still produces curlew chicks faster than it loses adults, and almost all the ground that does has a gamekeeper working on it. No published study shows what replaces that productivity if the shooting that funds it stops.
