Scientific name: Circus aeruginosus
Status: Resident breeding species and passage migrant
Breeding birds: 400 pairs
Conservation status: Amber
Length: 48 – 56 cm
Wingspan: 115 – 130 cm
Weight: 400 – 660 g (M) 540 – 800g (F)
Marsh harriers are the largest of the European harriers. Adult males have chestnut underparts streaked with brown and a darker rump which is more robust than the other harriers. Their tail is silvery-grey and their wings are bluey-grey with black primaries.
They have a brown back, rust coloured head and nape streaked with dark brown, and dark brown throat. Their eyes are yellow, and they have black bills with a yellow cere. Their legs and talons are yellow with rust coloured feathers on their thighs.
Adult female marsh harriers are more uniform in colour and slightly larger than males. They have a creamy head and throat, and fewer streaks than males. Their underparts are dark brown with brown wings and tail.
Juvenile marsh harriers are very dark brown with some creamy marks on their head, nape, and back.
Marsh harriers breed during the first few days of April. Males gather nest materials including sticks, reeds, and grasses and the female arranges them on a reed bed. During this time the female will remain by the nest and the male will bring her prey to eat.
Marsh harriers lay 2-8 bluey-white eggs with dark speckles which are incubated for 33-38 days. Feathers begin to grow on the wings of the chicks at 7 days and have full plumage at 28 days. They can fly at 35-40 days and leave the nest at 55-60 days.
Marsh harries prey on frogs, lizards, snakes, and small mammals and birds.
Where to see them
Marsh harriers can be seen in the UK all year round in eastern and south-east England. They arrive in their breeding grounds in April and leave during September and October.
Look out for them over reed beds and marshes, as well as farmland near wetlands.
Did you know?
Marsh harriers used to only migrate to the UK to breed leaving to winter in Africa. However, over time more and more individuals, usually females, are staying for the winter in the UK.