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Discover: Nature and Wildlife

Marsh Harriers

Jersey is one of the best places in the whole of the British Isles to see these majestic birds.

The Marsh Harrier (Circus aeruginosus) is a species of raptor (bird of prey) typically associated with wetland habitats such as reed beds and marshes.

Marsh Harriers generally express strong sexual dihorphism, meaning that males and females are dissimilar in appearance. Adult females are noticeably larger than males. Female plumage is mainly dark brown except for the head cap, chin, and the leading edge of the wings, which are paler in colour. Juveniles appear similar to adult females, except their crown and chin are more orange. Males tend to be reddish brown in colour except for the head, which is usually blue-grey, the tail, which is grey and unbarred, and the wingtips, which are black. In some populations however individual adult males sometimes exhibit permanent female plumage. This is known as permanent female mimicry, a phenomenon that to date has only been observed in two species of bird.

Marsh Harriers can be seen year-round in Jersey, but the months of October and November provide particularly spectacular viewing opportunities. At this time all of the Island’s Marsh Harriers (and possibly some individuals from neighbouring areas) congregate at St Ouen’s Pond in the late afternoon. They spend the afternoon gliding over the reed bed before settling down to roost at dusk.

Prior to 1998 Marsh Harriers were a rare sight in Jersey. In 2001 two individuals were recorded overwintering at St Ouen’s Pond and in 2002 the first instance of a pair of Marsh Harriers successfully breeding at the site was recorded. Since 2001 the breeding success story has continued, and Jersey’s Marsh Harrier population has grown considerably. In 2016 15 breeding pairs were recorded, although it is thought that as many as 8 pairs may be currently breeding in the island. While the majority of pairs nest in the reed beds of St Ouen’s bay, observations of breeding pairs have also been made at Les Maltieres marsh and Samares marsh. The number of individuals observed roosting in St Ouen’s bay during the winter of 2015-2016 peaked at 35.

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Best Places To See Marsh Harriers

La Mare au Seigneur (St Ouen’s pond)
St Ouen’s Pond on the west coast of Jersey is the Island’s largest area of freshwater wetland habitat, providing a haven for a vast diversity of wildlife. It has been acknowledged as one of the best places in the British Isles to observe Marsh Harriers as they are quite uninhibited by human presence and will fly within yards of the bird hides. More information can be found on the La Mare au Seigneur page.

La Mielle de Morville
La Mielle de Morville is essentially a dune slack wetland composed of reed bed interspersed with pockets of willow. Since 2009 a pair of Marsh Harriers have been recorded breeding at the site, successfully rearing 2 chicks in 2012. The best time of year to see Harriers at La Mielle de Morville is between April and July. From July onwards these Marsh Harriers tend to relocate to St Ouen’s Pond (approximately 500m South of La Mielle de Morville). There are three bird hides at La Mielle de Morville, providing fantastic opportunities for watching wildlife.

Les Maltieres marsh (Grouville marsh)
Les Maltières marsh is a mosaic of reed bed, wet meadow, and carr (wet woodland) habitat in the Parish of Grouville. It is Jersey’s second most important wetland site after La Mare au Seigneur (St Ouen’s pond). The National Trust for Jersey currently owns and manages 21 vergees (3.8 hectares) of this important wetland.

Reproduction

Marsh harriers reach sexual maturity by the age of 2-3 years. Males begin their aerial courtship displays towards the middle of March, with eggs being laid by females from early April onwards. Some individuals are polygamous (mating with more than one partner). Nests are constructed on the ground surrounded by tall vegetation (e.g. reeds) in or around suitable wetland habitat. Typical nest building materials include reeds, grasses, and small branches. Clutches of 2-8 eggs are laid in the nest, with individual eggs being laid sequentially at intervals of 2-3 days. Breeding pairs defend their nesting territory to a distance of up to 300m. Females are responsible for incubating eggs, brooding chicks, and hunting, while males tend to invest all their energy into hunting in order to provide adequate food for growing chicks. Males can often be seen passing food to females, who then deliver the food to the nest for chicks to eat. 28 days after hatching chicks start to explore the vegetation surrounding the nest. Fledging commonly occurs at 35-40 days, which is followed by dispersal from the breeding territory just over a month later (approximately 73 days after hatching).

Conservation

Marsh Harriers disappeared from Britain at the end of the 19th century due to widespread habitat loss and persecution. Thankfully, Marsh Harriers did subsequently recolonize areas of suitable habitat in Britain, and have been increasing in number ever since. This increase in population size prompted the Marsh Harrier to be removed from the UK Red List of animals at imminent risk of extinction. The recovery of Marsh Harrier populations in Britain is largely attributed to the habitat restoration and awareness raising efforts of conservation organisations.

Marsh Harrier Facts

  • Average Length: 43-54cm.
  • Wingspan: 115-130cm.
  • Marsh Harriers live and hunt in wetland habitats such as reed beds and marshes.
  • Males and females are dissimilar in appearance.
  • Most British individuals migrate to the Mediterranean region or North-West Africa in the autumn.
  • Some individuals remain in Britain year-round.
  • Jersey’s Marsh Harrier population has grown considerably, with 35 individuals recorded roosting in St Ouen’s bay during the winter of 2015-16.
  • Clutches of 2-8 eggs are laid sequentially at intervals of 2-3 days from April onwards.