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Sky dancing marsh harriers create stronghold

Male marsh harrier in flight at Wicken Fen
Male marsh harrier in flight at Wicken Fen | © National Trust / Richard Nicoll

The breeding season has begun for marsh harriers at Wicken Fen National Nature Reserve and what was once a rare occurrence is becoming a more common sight.

Driven close to extinction in the UK by the end of the 19th century, the marsh harrier has made a positive recovery in recent years. Reduced to one breeding pair in 1971 there are now thought to be around 600 breeding pairs in the UK.

With a stronghold in East Anglia, over reedbeds and marshes, as well as farmland near wetlands, rangers at Wicken Fen now look forward to their arrival each spring.

With their most successful breeding year in decades reported in 2020, when a dozen chicks fledged because of lockdown and less human activity on the reserve, National Trust rangers have continued to witness regular sightings of these birds over the reserve and hope for another successful year this year.

John Hughes, Area Ranger at the National Trust’s Wicken Fen, said: “Monitoring of breeding marsh harriers can be tricky, as they build their nests on the ground, hidden away amongst the reeds. Surveying for adults carrying nesting material and then subsequent food flights into these areas to feed young has helped us identify four marsh harrier nests this year. However, twenty years ago you would have been lucky to have witnessed these magnificent birds at all, now we’re enjoying regular sightings over Sedge Fen.”

The largest of the three harrier species with a wingspan of 122cm, the marsh harrier is an easy bird of prey to spot when it’s in flight, with wings held in a characteristic V-shape.

During the breeding season, the males perform amazing courtship displays, whilst females sometimes join in, locking talons mid-air. This impressive display known as ‘sky dancing’ is not just for show, but includes the passing of food to the female, ensuring she’s in prime condition for egg laying.

Nesting in large reedbeds, marsh harriers feed on frogs, small birds and mammals that live in or near wetlands. The male will continue to provide food for the female for the duration of her incubation of the eggs, which can last between 31 – 38 days and for a fortnight after the chick’s hatch. The eggs are laid at 2–3-day intervals, which means that the chicks don’t all hatch at the same time.

With an average of 5 chicks to feed, as well as the female, that’s no small undertaking. Marsh harriers are also bigamous, so one male will likely be supporting more than one nest.

John continued: “The restoration and re-creation of reedbed habitats at Wicken Fen will have helped support marsh harriers, although nesting in arable fields has also been important in their recent recovery. The withdrawal of certain insecticides and stronger legal protection has also helped pave the way for their revival.”

Although this is good news for marsh harriers, the UK is one of the most nature-depleted countries in the world and nature is in crisis. Over the last 50 years, 38 million birds have vanished from our skies, which is why the WWF, RSPB and National Trust are calling for an immediate halt to the destruction of UK nature and urgent action for its recovery. Everyone can play a part to Save Our Wild Isles.

Marsh harriers remain on the amber list, which is the second most critical conservation priority group.