Hen harrier facts

 

Hen Harrier (Circus cyaneus)

Identification

Like most birds of prey the hen harrier female is larger than the male.  Unlike most birds of prey, however, the sexes are completely different in appearance. While both have long narrow wings and tail and a white rump, the female is a rich tawny brown with a barred tail, while the male is grey with black wing tips. Sometimes he can look almost white and, at a distance, can be mistaken for a gull. The female’s wingspan is 75 cm and the male’s is 70 cm.

Calls

The Hen harrier makes two different and distinctive sounds. The first is a chattering or yikkering, which is usually heard as an alarm call in the vicinity of the nest. The second is a two-syllabled whistle, which is used by the female when it is begging food from the male.

Distinctive Behaviour

Both sexes usually begin nesting in their second year and they move to their nesting grounds in March. The display, called skydancing, is spectacular. While both will display, it is the male who will carry it out with most frequency and intensity. He will climb steeply into the sky before somersaulting and diving straight down. This will often be repeated many times across the nesting hillside.

The other spectacular aspect of their behaviour is the food pass. The male supplies the female with food before and during incubation and when the young are in the nest. The male approaches with food and the female flies underneath him, turning onto her back or side and catching the prey with a foot as he drops it.

Nesting

Usually hen harriers nest on heather moorland and will choose deep, rank heather to build their nests, in which they lay an average of 5 eggs at 2-day intervals. Laying takes place in late April and early May; the female incubates the eggs and they hatch in about 30 days. Since incubation starts before all the eggs are laid, hatching takes place over a number of days and so the young are of different sizes. This means that in years with a poor food supply and greater competition in the nest for it, the smaller chicks usually do not survive.

On average, two-three chicks survive and leave the nest after 30-35 days, but will remain around the nest site for several weeks to get food and to roost. They become independent after about 8 weeks.

After breeding, Hen harriers migrate south to coastal and low-lying areas.

Habitat, food, threats

Harriers nest on moorland, among trees in young forests and in heather patches in mature forests throughout the uplands of Britain. The main prey are voles, small birds such as Meadow Pipits and the juveniles of larger birds such as Red Grouse.

Being ground-nesting birds, the nests of harriers fall prey to predators such as foxes and other ground predators. Eagles may take adults birds. The main threat, however, is from man. The Hen harrier is still persecuted in parts of Britain because of a perceived conflict with grouse shooting. The habitat of heather moorland has been under pressure for many years from overgrazing and forestry, and nests are often lost through moorland fires.

Management

Hen harriers need deep heather in which to nest and a large area of open land on which to hunt. The nesting sites need to be relatively undisturbed during the breeding season. A number of upland forests can provide these conditions. The heather can be managed by burning or cutting to provide good habitat for voles and moorland birds and therefore provide the harriers with a source of food.

Forestry Commission works together with The Scottish Raptor Study Group and Scottish Natural Heritage in habitat management and monitoring of harrier nests.

Other interesting facts

• Up until the Second World War, harriers only bred on a few Scottish islands. Now there are about 500 pairs.
• Sometimes a male harrier can have more than 1 nesting female. Once, on Orkney, a male had 6 females!
• In winter, harriers group together to roost in long vegetation, often in lowland areas. Sometimes only a few birds come together but other times up to 60 may roost in one place.