Natural England’s Final Hen Harrier Reports Strengthen the Conservation Case for Brood Management

Quick summary

• Natural England’s final reports show hen harrier numbers rose sharply where brood management was available.

• Nesting increased on grouse moors where brood management was available, but not where it was unavailable.

• Owners described it as a lawful “safety valve” that built trust and encouraged coexistence.

• Trial licences have lapsed; the Moorland Association seeks a practical, multi-year conservation licence.

Natural England has published the full evaluation reports from the Hen Harrier Brood Management Trial.

Taken together, they provide important new evidence about what happened during the trial, why hen harrier numbers increased so markedly and the role that the availability of brood management appears to have played.

The reports do not suggest that brood management alone can resolve every aspect of the long-running hen harrier conflict.

They do, however, support a conclusion of considerable significance: the scenario best supported by the available evidence is that having brood management available enabled more hen harriers to breed successfully on grouse moors.

That materially strengthens the case for a practical and proportionate conservation-licensing framework.

The origins of the trial

The brood management trial was one of six actions in the Government’s 2016 Joint Action Plan to increase the English hen harrier population.

The plan set two linked tests of success: England should have a self-sustaining and well-dispersed breeding population of hen harriers, including within the Special Protection Areas designated for them, while that population should coexist with local business interests and contribute to a thriving rural economy.

Brood management was designed to help reconcile those objectives. Where hen harriers nested at a sufficiently high local density to have a significant effect on red grouse numbers, eggs or chicks could be temporarily removed under licence, reared in captivity and released back into suitable habitat.

The aim was to provide a lawful means of managing acute local conflict and give land managers confidence that increasing hen harrier numbers would not make the continued management of a grouse moor unviable.

The trial ran from 2018 to 2024, with practical brood management taking place between 2019 and 2023. Fifteen broods were managed and 58 young hen harriers were successfully released. Ten estates were involved as intervention or release sites.

The Moorland Association worked with its members to deliver the project alongside the International Centre for Birds of Prey, Natural England, the Game & Wildlife Conservation Trust and the Hawk and Owl Trust.

The technique worked and hen harrier numbers increased

Natural England’s final evaluation concludes that hen harrier eggs and chicks could be safely taken into captivity, reared and returned to the wild, with no negative effects attributable to captive rearing detected. Released birds behaved normally and some subsequently bred or attempted to breed.

The trial has therefore established practical knowledge, veterinary experience and operational expertise that did not previously exist.

It also coincided with a substantial increase in the English hen harrier population. The BTO describes the rise from 2018 as sudden and rapid. England’s recovery was also markedly stronger than that of neighbouring populations. From only four territorial pairs recorded at the 2016 census, the English population increased more than tenfold during the trial period.

Wales, Scotland and the Isle of Man saw much smaller changes, while the Southern Uplands population declined. That makes a broad environmental explanation, such as weather or prey availability across the whole region, less convincing on its own.

Natural England found that nesting numbers increased significantly in areas managed for grouse shooting.

Natural England’s own analysis is particularly striking. Nesting increased significantly on grouse moors where brood management was available or used, but not on grouse moors where it was unavailable. It also found no significant difference between estates that actually used brood management and those where it was simply available.

That points to the value of the lawful safety net itself. The effect was not confined to the small number of broods physically removed and reared; simply knowing that a credible management option existed appears to have influenced confidence and behaviour more widely.

How brood management appears to have worked

The BTO modelling found that the direct benefit of rearing and releasing additional chicks could not, by itself, explain the scale of the population increase.

The more plausible explanation requires an improvement in survival, settlement, or both. In this context, “settlement” includes breeding-age birds beginning nesting attempts and those attempts surviving long enough to be detected.

Reduced disturbance immediately before or during the early stages of nesting is therefore one plausible explanation. Improved survival may also have played a part, although the modelling cannot determine precisely how much survival changed or why.

The social-science evidence helps explain the possible mechanism. Participating owners, managers and gamekeepers described brood management as a “safety valve”. Its availability helped allay concerns that hen harrier numbers might rise locally to levels at which a grouse moor could no longer remain economically viable.

Natural England found evidence of changing attitudes and behaviours among those who participated directly in the trial. Participation also strengthened trust between moorland owners, keepers and the Natural England staff working with them on the ground.

The central theory behind the trial has therefore received substantial evidential support: a lawful management option can help sustain confidence, encourage coexistence and enable more hen harriers to settle and breed successfully.

Natural England also records that the increase was not associated with any large-scale change in enforcement activity. This reinforces the conclusion that cooperation, confidence and changing behaviour on the ground played an important part in the recovery.

Practical problems remain

The evaluations also identify real costs and practical difficulties. Survey respondents reported financial pressure, interference with estate operations, reduced grouse numbers, restrictions on release sites and uncertainty over future licensing.

Those findings should not be overlooked. They show that participating estates helped deliver an increase in hen harrier numbers despite reporting costs to their own businesses. That strengthens, rather than weakens, the evidence of a genuine commitment to conservation and coexistence.

It also explains why any successor scheme must remain workable.

Brood management was never intended to become a routine intervention on every moor. It is a targeted measure for circumstances in which unusually high local nest densities create acute conflict. Future licensing should therefore be flexible enough to respond to annual nesting patterns while maintaining appropriate welfare, conservation and legal safeguards.

Illegal killing has not been eliminated

Natural England could not conclude from the available police data that illegal killing had declined generally across England. It did, however, find that the main geographical hotspots for suspected or confirmed offending did not overlap with the principal areas where brood management had taken place.

Natural England considers it likely that illegal interference or disturbance reduced to some extent in some areas, although the evidence does not establish the precise mechanism or show a general decline across England.

This points towards a differentiated approach. Where land managers are cooperating and hen harriers are breeding successfully, the priority should be to maintain trust, recognise responsible practice and ensure lawful management tools remain available. Persistent offending requires properly targeted investigation and enforcement.

Brood management is not an alternative to enforcement, but enforcement alone is not a complete response to a complex conservation conflict.

What happens next

Natural England’s evaluation does not recommend a successor mechanism, and the trial licences have now lapsed. That leaves a clear policy gap: a lawful tool which appears to have contributed to recovery is no longer available to address the circumstances for which it was designed.

The Moorland Association is seeking to fill that gap through its Hen Harrier Conservation Project Plan and a practical, multi-year conservation licence.

The new evidence supports a scheme focused on:

• maintaining land-manager confidence and responsible participation

• enabling more hen harriers to settle and breed successfully

• providing a lawful response to acute local nest-density conflict

• proportionate monitoring and transparent reporting

• timely licensing decisions and suitable release sites

The evidence also means the case for future licensing must be stated accurately. The population increase cannot simply be presented as the direct result of rearing and releasing additional chicks.

The stronger case is that brood management operated as a lawful safety net. Its availability appears to have changed behaviour and helped more wild hen harriers settle and breed successfully.

Natural England’s reports do not suggest that brood management is a complete answer, nor do they remove the need to address illegal activity wherever it occurs.

They do, however, provide strong official evidence that brood management has a legitimate continuing role in hen harrier conservation.

The sharp fall in nesting numbers in 2024 also demonstrates how quickly progress can stall or reverse, reinforcing the need for continuity, further analysis and a credible future framework.

The priority must now be to translate that evidence into a practical and proportionate licensing framework - one that supports further hen harrier recovery, sustains cooperation on the ground and delivers the coexistence envisaged by the Government’s original Action Plan.