This video says about itself:
Northern Harrier (Marsh Hawk) Circus cyaneus [called hen harrier in Britain]
* Family: Accipitridae,
* Genus: Circus,
* Species: C. cyaneus,
* Phylum: Chordata,
* Class: Aves,
* Order: Falconiformes or Accipitriformes,
* Type: Bird,
* Diet: Carnivore,
* Average lifespan in the wild: about 12 years,
* Size: 45–55 cm long with a 97–118 cm wingspan,
* Weight: average of 350 g to 530 g,
** The northern harrier is a sleek bird of prey with a long, narrow tail. The adult male is a pale gray color and the female has a brown back and brown-streaked belly.
More info here and here.
From Wildlife Extra:
Future for hen harriers looking bright in the Peak District
With the fledging of five hen harrier chicks, it seems that hen harriers are once again breeding successfully in the Peak District for the first time in eight years.
This is great news for the hen harrier, as the bird has been at serious threat in England for over sixty years, with their numbers declining primarily due to illegal persecution. In 2013 just two breeding pairs were reported in England, and no young fledged [for the first time] in over fifty years.
The hen harriers were nesting on land cared for by the National Trust in the Upper Derwent Valley. In late April 2014, two male hen harriers and a female were seen sky-dancing, which is the spectacular aerobatic mating routine of the birds. Then in early August, a nest containing five chicks was discovered by Geoff Eyre, a local National Trust shooting tenant. He alerted the Peak District Birds of Prey Initiative, who put a nest watch team in place to monitor the nest daily.
The Trust puts the success down to collaboration with a wide partnership of people and organisations, who all share the goal of protecting the birds and their nest as part of the National Trust’s High Peak Moors Vision, aiming to restore birds of prey in the area. “Having hen harriers breed successfully here in the Peak District is wonderful news,” comments Jon Stewart, the National Trust’s General Manager for the Peak District, “and would not have been possible without the hard work and commitment of all the people and organisations involved, which has been truly inspiring.”
The Trust continues to work closely with tenants and partners of the area, including the grouse-shooting community, in order to pursue the goal of its High Peak Moors Vision, which is committed to increasing the number of birds of prey on National Trust land in the Peak District.
Commenting on the fledging of the hen harrier chicks, Jon Stewart says: “This success is the first step towards a sustainable future for these magnificent birds; a future that can only be achieved by everyone continuing to work together, both here and across the English uplands.”
If you are lucky enough to see a hen harrier in the wild, the National Trust and the RSPB encourage you to report the sighting. You can do this via calling the hen harrier hotline on 0845 4600121, or emailing firstname.lastname@example.org. Please be prepared to include the date and location of the sighting, and a six-figure grid reference where possible.