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 Marsh Harrier - Fact File

Marsh Harriers
female (left) male

Circus aeruginosus
Once very rare, has increased in recent years and is now locally common in parts of England with large reedbeds.
Marshes with extensive reedbeds. Also sometimes in farmland away from reeds.

Largest of our harriers. Adult male has distinctive plumage pattern (see illustration), and female has cream crown and brown body. Wings held in characteristic V-shape.

48 - 56cm (19 - 22")
 

Marsh Harrier

Any list of Norfolk ornithological successes must include the marsh harrier. The county's population of these fine birds is higher nowadays than at any previous time this century.

In the summer of 1993, 98 adults raised a total of 114 young to the flying stage. At one site a single male was mated to three females and each successfully reared young.

Traditionally these harriers have nested in large reedbeds. But during the last 16 years almost a third of the population has taken to breeding in cereals. The first such nest, in winter barley, was saved from disaster by a vigilant combine driver. He readily vouched for the lightning reflexes and razor sharpness of the nestlings talons! All three young were safely on the wing a few days later.

Despite the remarkable achievements of recent years, it is in my recollection that there was a 12-year period from 1960 when only a single young marsh harrier was raised in Norfolk. In five of these seasons the only really successful breeders in the whole country were at Minsmere. Marsh harriers do not breed until their third summer. With a population so critically low it would not have been surprising if it had disappeared as a breeding bird.

The recent impressive increase here in breeding marsh harriers was doubtless helped initially by arrivals from the continent. By far the largest population close to East Anglia is in the Netherlands where there has been a steady increase despite a drastic reduction in reedbed areas in the reclaimed polders.

One important marsh harrier colony breeding in cereal crops is guarded by a full-time warden employed by RSPB. Before autumn dispersal the harrier families form impressive roosts and the most spectacular number to date appeared in 1991.

Marsh Harrier showing classic V shapeOne season, a warden found 18 birds including six males assembling to roost in a wheat field. The very next evening, harvesting was finishing shortly before dusk just as the harriers began arriving. Unsure, the great birds circled round and round until 14 dropped into a nearby small area of reed for the night. A remarkable scene!

Even more excitement was to follow. The reedbed, despite its limited size, attracted an incredible 36 harriers attaining a peak arrival September 1. This total included at least 10 males. The reedbed continued its attraction until the month-end.

At each season marsh harriers provide fascinating watching. During the long periods of incubation and tending young which are performed almost entirely by the female, food is provided by her partner.

This lengthy phase provides opportunities to watch spectacular aerial food passes. Well before the cock is over the nest, the hen rises and approaches him from below, turns over almost upside down and catches the prey as he drops it. If the wind is fresh and the prey is small, transfer is made claw to claw. But sometimes it tumbles several feet before the female catches it. Very rarely she misses.

Michael J. Seago

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Illustrations by Dave Nurney from - The Pocket Guide to the Birds Of Britain and North-West Europe By Chris Kightley and Steve Madge
© Pica Press and reproduced with kind permission.