The Hen Harrier - Circus cyaneus - or Northern Harrier – in North America. In the UK, the Hen Harrier suffers illegal persecution by gamekeepers and their employers on shooting estates, particularly those managed for Red Grouse shooting, resulting in local and regional extinction in many areas.

In a 2011 joint survey of the English uplands by the RSPB and Natural England found that only four nesting pairs of Hen Harrier successfully raised young; all were on a single estate in the Forest of Bowland, Lancashire. This is believed to be the lowest population in England since they decolonized in the 1960s following extinction in the late 19th century. Historically, the Hen Harrier was widespread in England.

A demonstration partnership project at Langholm Moor, in the Scottish Borders, is looking at the effectiveness of a measure known as 'diversionary feeding', where an alternative food supply is left for the harriers, so that the birds have a source of food and won't be tempted to take Red Grouse chicks. Early results look promising, enabling the birds to nest successfully without causing alarm to grouse moor owners and managers. Preliminary results show that no grouse chicks have been brought to monitored Hen Harrier nests in four years at the study site. Martin Harper of the RSPB's believes the potential for diversionary feeding will provide a lifeline for the recovery of the English Hen Harrier.