Background The hen harrier (Circus cyaneus) is a species of European conservation concern and is listed in Annex I of the Birds Directive. After several decades of recovery in the UK, the population is currently declining. While the reason for this is not fully understood, it is clear that illegal persecution associated with commercial shooting of red grouse (Lagopus lagopus scoticus) is a significant factor. The decline is particularly serious in northern England and southern and eastern Scotland, where the hen harrier is nearing extinction as a breeding species. Other factors that are likely to be impacting breeding success include inappropriate land management, human disturbance, and predation of eggs and young from nests. Recent analyses published by the UK government indicate that enough suitable habitat exists to support up to 2 650 pairs in the whole of the UK (compared to 630 pairs in 2010), suggesting that, in the long term, the potential for population growth in the absence of persecution is significant. Objectives The LIFE project focuses on the protection of hen harriers from illegal persecution. The aim is to provide the conditions in which hen harrier range and population recovery can occur. Within the timeframe of the project, the key priorities are to prevent the extinction of the hen harrier as a breeding species in northern England, and to arrest its decline in southern and eastern Scotland, as vital first steps towards a recovery that may take at least 10 years. The project combines ‘preparatory’ work with conservation and communication actions. Data from preparatory activities will guide targeted conservation measures to protect hen harrier, and to collect evidence to support law enforcement actions combating illegal persecution. Species protection work will be supplemented by habitat management and advisory work designed to provide suitable conditions for breeding and wintering at key project sites. Satellite tags will be fitted to nestlings to obtain accurate information on hen harrier movements and the nature of persecution outside the breeding season through the dispersal corridors to the wintering areas. The novel surveillance technologies used are potentially applicable to similar species protection projects. The main objectives are to: Improve understanding of the movements of hen harriers in northern England and southern and eastern Scotland, and of the intensity and nature of persecution in this core project area, especially outside the breeding season; Make use of this improved understanding to enhance protection of hen harriers at breeding sites and at wintering sites; Ensure that habitat availability does not limit harrier recovery; Raise public awareness of hen harriers, the threats they face and conservation efforts to overcome these; and Encourage recognition by local communities and land managers of the hen harrier as an iconic species of upland landscapes, and thus increase support for its protection. Expected results: Suitable protection measures deployed at all breeding sites in England and at least 75% of breeding sites in southern and eastern Scotland, including new sites identified during the project; Important wintering sites within the project area identified, and protection measures introduced at as many of these sites as possible; Management work carried out at three key sites in northern England to ensure that the rate of hen harrier recovery is not limited by the availability of good-quality habitat; A plan to maintain and extend hen harrier conservation work after the project; An assessment of the potential to apply novel technologies to other species protection projects; Awareness of and empathy with the hen harrier significantly improved among key stakeholder groups, local communities and national audiences; Between five and 15 pairs of hen harrier breeding successfully in northern England, and at least 35 pairs breeding in southern and eastern Scotland, in 2019; and The hen harrier’s breeding range in the UK to be larger at the end of the project than at the beginning.