How Rising Predator Numbers Are Threatening Britain’s Moorland Birds

Generalist predators like carrion crows and foxes have thrived in modern Britain. Their rise has come at a cost - particularly to our most vulnerable ground-nesting birds. As apex predators vanish and gamekeeping declines, curlews, lapwings, and black grouse are struggling to survive.

This blog examines the growing imbalance, the role of predator control in conservation, and the case for supporting traditional moorland management as a vital tool in protecting upland wildlife.

Increased Generalist Predators

Generalist predators, such as Carrion Crows and Red Foxes, have seen significant population increases in the UK in recent decades. These populations are among the highest in European countries. This rise is attributed to several factors:

• Transformed Landscape: The UK landscape has been heavily shaped by intensive agriculture and the planting of non-native woodlands, which provide more food and offer refuge and breeding sites for predators.

• Missing Apex Predators: The loss of large apex predators like wolves and dramatic drops in golden eagle and goshawk numbers, means there are fewer natural controls on mesopredator populations. Their absence allows generalist predators to thrive.

• Reduced Gamekeepers: Fewer gamekeepers on the land have also contributed to the increase in predator numbers.

Impact on Moorland and Ground-Nesting Birds 

The rise in generalist predator populations poses a major threat to ground-nesting birds and their nests, including eggs and chicks. These birds are particularly vulnerable because they nest on the ground.

Curlew Decline

The evocative call of the curlew, once common across the UK, is becoming increasingly rare due to rapid population declines. The curlew population has halved in the last 25 years. Studies show predation rates on curlew nests have increased significantly.

In the Berwyn Special Protection Area (SPA) in North Wales, curlew numbers dropped by a staggering 79% after traditional moorland management, including predator control, ceased. An ornithologist noted the "disastrous decline" in curlew breeding populations, attributing a significant driver to the "burgeoning corvid population".

At Lake Vyrnwy, an RSPB reserve where controlled burning stopped in 2003, only one pair of curlews nested in 2024, despite substantial taxpayer funding. The RSPB's own data indicates a decrease in red-listed birds like black grouse and curlew at Lake Vyrnwy since the 1990s.

Widespread Declines 

Other ground-nesting birds have also experienced dramatic declines when predator control ceased:

• Lapwing: Lost entirely from surveyed areas in Berwyn by 2002. In a North Northumberland experiment, Lapwing declined by 58% ten years after predator control stopped.

• Golden Plover: Numbers plummeted by 90% in Berwyn and decreased by 81% in the North Northumberland experiment.

• Black Grouse: Declined by 78% in Berwyn and became locally extinct in the North Northumberland study plots ten years after predator control stopped.

• Red Grouse: Numbers declined by 74% in the North Northumberland experiment and by 54% in Berwyn.

• Snipe: Decreased by 76% in the North Northumberland experiment.

• Grey Partridge: Became locally extinct in the North Northumberland study plots.

• Ring Ouzel: Numbers declined by 78% in Berwyn.

Reduced Breeding Success

Without predator control, the breeding success of ground-nesting birds is severely impacted. For example, curlew breeding success was only 15% without legal predator control, leading to a 17% annual population decline. To maintain stable populations, lapwing need to produce around 0.87–0.97 fledglings per year, and curlews need 0.48–0.62 fledglings per pair, which is largely unattainable without intervention.

Predator Control as a Conservation Tool 

Predator control has proven to be a vital conservation measure when used to protect ground-nesting birds.

Effectiveness

Studies have consistently shown that controlling key predators like foxes and crows significantly improves breeding success. For example, a study at Otterburn in Northumberland found that legal removal of predators resulted in a three-fold improvement in breeding success for lapwing, golden plover, curlew, red grouse, and meadow pipit.

Curlew pairs on grouse moors raised four times more chicks than those on non-grouse moors (1.05 vs. 0.27 fledglings per pair). This improved success translates into increased breeding numbers for species like lapwing, golden plover, curlew, and red grouse.

Necessity

The rapid declines and local extinctions of ground-nesting birds were strongly associated with the recovery of legally controllable predators after their removal ceased. This suggests that continued lethal predator control may be necessary to support these bird populations, especially in the short to medium term.

Mary Colwell, Founder and Director of Curlew Action, has stated that conservationists may have to choose between having gamekeepers (who practice predator control) with curlew, or having no gamekeepers and no curlew.

Cost-Effectiveness

Predator control is a costly endeavor, requiring sustained annual effort. However, on private grouse moors, this work is already performed by gamekeepers for shooting interests, meaning wild curlew chicks fledged there can be seen as costing £0 of public money. Gamekeepers on driven grouse moors protect an estimated 53% of the English Curlew population at no public cost.

Grouse Moor Management and Predator Control

Grouse moor management plays a pivotal role in predator control and, consequently, in the conservation of ground-nesting birds.

Integrated Approach

Legal predator control is a cornerstone of "integrated moorland management" on grouse moors, alongside heather management and disease regulation. Gamekeepers, as part of their year-round duties, systematically reduce numbers of generalist predators like foxes, crows, stoats, and weasels.

Refuges for Wildlife

Grouse moors are one of the last remaining strongholds for curlews. Studies consistently show higher densities and breeding success of curlews, lapwings, golden plovers, merlins, and black grouse on moors actively managed for red grouse compared to other types of moorland.

Approximately 53% of the UK’s curlew population and 42% of its lapwing population are found on English grouse moors associated with Regional Moorland Groups.

Benefits Beyond Grouse

While undertaken primarily to maximize red grouse numbers, the predator control on grouse moors significantly benefits a wide range of other ground-nesting birds. For example, merlins also benefit from the reduction of generalist predators like foxes and stoats on moors. Black grouse leks supported twice as many males where driven red grouse shooting was active, likely due to predator control.

Other Threats to Moorlands and Wildlife

While increased predation is a major factor, other threats contribute to the decline of moorland species:

• Habitat Loss and Degradation: Modern farming practices like drainage, fertilizers, and grass reseeding have made many areas unsuitable for curlews. Increased sheep grazing has also led to habitat loss. Changes in grazing patterns and the absence of heather burning have led to vegetation changes that can make habitats less attractive to certain species. The maturation of commercial forests can also reduce open moorland habitat.

• Wildfires: Wildfires pose a significant threat to peatlands, which are crucial carbon stores. Unmanaged vegetation can lead to increased fuel loads, making moorlands highly susceptible to wildfires. Traditional practices like "cool burning" of heather help reduce fuel loads and wildfire risk.

• Over/Under-grazing: Both overgrazing and under-grazing can have detrimental effects on heather moorland and biodiversity. Under-grazing, for instance, can lead to increased tick numbers, which spread diseases to both wildlife and humans.

• Rewilding: Some critics argue that rewilding initiatives can increase wildfire risk by allowing fuel loads to build up naturally.

• Disease: Diseases and parasites, like louping ill and strongyle worm, are routinely monitored and controlled on grouse moors, benefiting wild and domesticated animals.

Conclusion

While various factors contribute to the decline of moorland wildlife, particularly ground-nesting birds, the unchecked increase of generalist predators plays a critical role.

Traditional moorland management, especially through privately funded predator control efforts on grouse moors, provides essential protection and enables many vulnerable species to thrive. Without these interventions, alongside habitat protection and restoration, the continued decline and local extinction of iconic moorland birds are highly likely.

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