Hen Harriers on the rise, but illegal persecution continues to stifle their recovery

Male Hen Harrier, (c) Pete Morris, rspb-images.com

This blog is written by Mike Shurmer, RSPB Head of Species, following the publication of the latest Hen Harrier Survey results.

The results of the sixth national Hen Harrier Survey have been released today, providing an essential update on the conservation status of this Red-listed species.

The survey was carried out across the UK in 2023 as a partnership between the RSPB, NatureScot (NS), Natural Resource Wales (NRW), Natural England (NE), Northern Ireland Environment Agency (NIEA), the Scottish Raptor Study Group, the Northern Ireland Raptor Study Group, Northern England Raptor Forum and Manx BirdLife.

The headline figures show some cause for optimism – the population is now estimated to be 653 (95% confidence limits (CL), 555-764) territorial pairs, a 20% increase from the 545 (95% CL, 447-664) pairs recorded in the last survey in 2016. This also arrests the trend of decline shown since the 2004 survey, when 749 (95% CL, 675-832) pairs were recorded.

However, the results of the survey show that there is still much work to do. The population remains 13% below the peak 2004 figure (a decrease that is marginally non-significant), though recovery to the 2004 population size should not be the sum of ambition. In 2011, an independent government report, based on the 2004 national survey data, found that there was sufficient suitable habitat for the UK to hold an estimated 2514–2653 pairs of Hen Harrier. The figures from the 2023 survey show that the UK population is just 25% of its potential.

We welcome the overall increase in the UK population, but a closer look finds there is much variation across their UK range. Below we consider this for each of the UK countries.

Hen Harrier brood, (c) RSPB Investigations team

England

As previously reported by Natural England, there were 54 Hen Harrier breeding attempts by 50 territorial pairs in 2023. This represents a substantial 1,150% increase from the four pairs recorded in the 2016 survey. However, the 2023 population represents only 15% of the potential population that suitable habitat can support and Hen Harriers remain absent from large parts of England’s uplands. For example, there were no breeding pairs in the Peak District in 2023, despite breeding in previous years, or the North York Moors.

The increase in Hen Harriers in England coincides with Defra’s Joint Hen Harrier Action Plan, which comprises six actions to support their recovery. One of these actions is the brood management trial, which we blogged about last November. Whilst initial analysis has reported higher first-year survival rates of brood-managed compared to wild-reared young, a core aim of the trial is to see an attitude change leading to less Hen Harriers being illegally killed. As reported by NE in January 2024, disappearances and proven persecution incidents of satellite-tagged birds continue. Losses in 2023 were higher than normal, including of some birds that were part of the brood management trial. In fact, combining NE and RSPB tagging data shows that a shocking 32 satellite-tagged Hen Harriers vanished or were confirmed persecuted in England in 2023.

Scotland

There was a mixed picture for Hen Harriers in Scotland. The overall population was estimated at 529 (95% CL, 431-640) territorial pairs, giving Scotland 77% of the UK and Isle of Man population, and an overall (non-significant) increase of 15% since 2016. However, the 2023 Scottish population is less than a third of the potential population that the suitable habitat can support, with numbers 16% below the population in 2004 (a decrease that is marginally non-significant), and numbers breeding on grouse moors continue to decline.

For the first time since national surveys began, the Hebrides held the second largest proportion of the Scottish population, with an estimated 110 (95% CL, 62-166) territorial pairs being a 125% increase since 2016. Much of this can be attributed to an expanding population on Lewis since 2016. There was also a significant increase of 69% in the East Highlands, with this due, in no small part, to steady increases on two large ‘habitat regeneration’ landholdings.

Orkney and the North Highlands showed increases of 15% and 12% respectively, and while the West Highlands showed a modest decline of 5%, in the Southern Uplands there was a steeper 32% decline. Despite four Special Protection Areas (SPAs) being designated for this species in the south of Scotland, they now only breed on one.

Unfortunately, satellite-tagged Hen Harriers from Scotland also continue to disappear, suddenly and suspiciously, and, as described in the RSPBs 2022 Birdcime report, invariably in areas managed for driven grouse shooting, in Scotland or in northern England. While the population of north and west Scotland is showing an increase, it’s likely that ongoing persecution continues to constrain their numbers on the grouse moors of the east and south.

Wales

The 2023 survey recorded 40 territorial pairs, a 14% increase since 2016, which makes up some of the decline that occurred between 2010 and 2016. More than half of the Hen Harrier pairs were in the two SPAs designated for breeding harriers, Berwyn in Northeast Wales and Migneint-Arenig-Dduallt in the northwest but as elsewhere in the UK, Hen Harrier is far less abundant or widespread than it should be, and the new population estimate represents only 16% of the potential population that suitable habitat can support.

Northern Ireland

In Northern Ireland there were 34 territorial pairs recorded in 2023. This represents a 26% decrease between 2016 and 2023, with this decline linked to loss of habitat and increasingly poor habitat quality, with illegal persecution continuing to be a significant issue for raptors in Northern Ireland. The decline mirrors the population decrease within the Republic of Ireland in 2022 (Ruddock et al. 2024).

The 2023 Northern Ireland population represents only 22% of the potential population that the suitable habitat can support.

Summary

Whilst the overall increase of Hen Harriers in the UK since the 2016 national survey is very welcome, it is apparent that significant complex issues remain for Hen Harriers in the UK. With the UK population at around 25% of its estimated potential, there remains much to do to secure a meaningful recovery. The reasons for Hen Harriers continuing to be far below their potential population are complex, but one of the primary causes is that continuing illegal killing, typically associated with intensive driven Red Grouse management, is stifling their full recovery.

This March saw the five-year anniversary of a seminal NE study by Murgatroyd et al. (2019), which revealed that Hen Harriers were ten times more likely to die or disappear in areas predominantly covered by grouse moor compared to those that were not managed for grouse. It concluded that at least 72% of tagged Hen Harriers were either confirmed to have been illegally killed or disappeared suddenly with no evidence of a satellite tag malfunction. The scientific evidence base has grown further, with a peer-reviewed paper published by Ewing et al. (2023) finding that the annual survival of Hen Harriers in the UK is unusually low, with illegal killing accounting for 27-43% of annual mortality in birds under one year of age, and as much as 75% of mortality in Hen Harriers aged between one and two years old. Mortality due to illegal persecution was found to be higher in areas managed for grouse shooting.

The mutilated body of a satellite-tagged male Hen Harrier, known as Free, was recovered on moorland in the Yorkshire Dales National Park in April 2022. A post-mortem examination reported that Free’s head and leg had been pulled from his body while he was alive. It was concluded that these injuries could only have been carried out by a person, as there were no other signs of predation (Credit: Natural England)

With persecution of Hen Harriers continuing unabated – for example, just last month another satellite-tagged Hen Harrier ‘Shalimar’ disappeared in suspicious circumstances in the Angus Glens – it is essential that meaningful efforts are stepped up to end illegal killing associated with unsustainable gamebird management. the vote in favour of the Wildlife Management and Muirburn Bill by the Scottish Parliament on 21 March, all grouse shooting in Scotland will require a licence with the potential for suspension/removal of licences in the future if there is evidence of wildlife crime, such as raptor persecution, linked to shoot management. In England the RSPB are upping our calls for the licencing of driven grouse shooting, so that skydancing Hen Harriers become a familiar sight across our uplands.

The national 2023 Hen Harrier survey was co-funded by NS, NRW, NE, NIEA and RSPB with the fieldwork being carried out by expert licensed volunteers supplemented by professional surveyors from the RSPB Centre for Conservation Science. We welcome the support of the many landowners, land managers and farmers in facilitating this survey.