GWCT expands landmark study into red grouse declines

The GWCT has launched the most ambitious study of red grouse declines yet undertaken, expanding its Maternal Grouse Project across northern England and into the Scottish Highlands. Announced as the season opened on 12 August, the research follows radio-tagged hens from before laying until their chicks fledge, to establish why breeding success keeps failing on some moors.

What is the Maternal Grouse Project?

The project, now in its fourth year in northern England, pairs almost 45 years of standardised spring and summer counts with intensive fieldwork on individual hens. In March, researchers tagged 60 hens across four long-standing study sites in the North Pennines and 51 more across four new sites in the Scottish Highlands, with a further expansion into southern Scotland planned for 2027.

Nick Hesford, director of GWCT Scotland, said: “For decades we’ve known what grouse populations are doing because we’ve monitored them consistently across the uplands. What the Maternal Grouse Project allows us to understand is why some populations have remained consistently low and what’s been driving recent declines and failures to breed successfully.”

He added: “By following individual hens from before they lay until their chicks fledge, we’re beginning to uncover how nutrition, weather, habitat and disease interact to influence breeding success. It’s a level of understanding that simply hasn’t been possible before.”

How bad are the red grouse declines?

Spring monitoring in 2025 recorded pair counts down by an average of 40% in England and 34% in Scotland, the legacy of the poor 2024 breeding season, while summer brood counts showed adult numbers down a further 36% and 29% respectively.

There was better news in the young-to-old ratios, which recovered to 1.4 in England and 1.3 in Scotland, up from 0.9 and 0.6 the year before. But the trust says no single cause explains why some moors keep failing while neighbouring ground thrives, which is precisely the question the expanded study is built to answer.

What do the fieldworkers measure?

Rather than examining parasites, disease or predation in isolation, the study measures how the pressures interact. Leah Cloonan, GWCT uplands advisor, who leads the English fieldwork, said: “For six weeks starting in March, prior to nesting, we take heather samples every week, the main food source of red grouse.”

She added: “In the last week of April we start to locate nests. Once we locate a nest, we note the clutch size, measure the eggs and insert a small temperature data logger into the nest lining.”

Fieldworkers also record cottongrass emergence, cranefly abundance and worm burdens. New this year is rainfall captured site by site. “Damp ground is important for the emergence of key invertebrate species, but too much rainfall can have a detrimental effect on the survival of chicks,” said Ms Cloonan.

What happens next?

Fieldwork continues through this season on all eight study sites, and the project expands into southern Scotland in 2027. Mr Hesford said: “The ultimate aim of the Maternal Grouse Project is to identify factors limiting red grouse breeding success and translating this into practical guidance that can help estates build more resilient grouse populations and deliver more consistent grouse bags in the years ahead.”

The full announcement, with details of the study sites and methods, can be read on the GWCT website via the link below.