Ghosts of Wicken Fen: Enjoying the stunning sights of hen harriers and barn owls

In the long, cold winter nights, many birds retreat to communal roosts each evening, in relatively safe sites: high in the trees in the case of rooks, for example, or for starlings, low down among dense vegetation.

There is safety in numbers, with birds likely to alert others to potential danger, as well as the extra warmth gained from bodies huddled close together.

Starlings are justly famous for their dusk gatherings, and hundreds may be seen swirling together in amazing aerobatic displays as they swoop about above favoured roosting sites, smaller flocks coalescing into massed clouds of smoke-like quality. As each bird adapts to the movements of its closest neighbours, collisions are avoided although the birds are almost touching at times. Eventually, the swirling feathery clouds circle ever closer to the roosting area and individuals drop down to find a resting place for the night.

We made a visit to Wicken Fen one afternoon, hoping to experience such roosting behaviour. We waited patiently in a hide overlooking fields of reed and sedge, backed by scrub and trees, and sat and gazed out over the quiet fenland habitats.

High overhead, straggling flocks of black-headed gulls, joined from time to time by common gulls, drifted north from the Mere, probably to roost together on the Ouse Washes. Among the trees small flocks of fieldfares and redwings sought shelter in the branches and bushes.

Then in the background beyond the lode and above the reedbeds of Adventurers’ Fen small groups of starlings began gathering and merging into larger flocks, eventually creating a mesmerising aerial mass that seemed to take on a life of its own; a shape-shifting amoeba, or something supernatural. Quite a spectacle!

The dense reedbeds to the south of the reserve were their probable destination, where the vegetation and muddy water beneath would keep them safe from foxes and other predators.

One of the star birds of Wicken is the majestic marsh harrier, and I rarely visit the fen without spotting these beautifully agile raptors as they twist and circle over the wetland habitats.

We were not disappointed on this occasion either and two or three floated in and around the trees and bushes beyond the reeds and sedge fields.

But we had really come to the fen in the hope of spotting Britain’s rarest bird of prey, a close relative, the hen harrier. These graceful birds breed on the moors and uplands of the north and spend the winter in the lowlands and coastal marshes.

They have suffered from habitat loss and illegal persecution, especially on grouse moors, and only a handful now breed in England.

The good news is that they are slowly increasing, and in 2021 there were 31 recorded breeding attempts in England, of which 24 were successful, with 84 chicks fledging.

We sipped coffee and kept watch over the marshy ground in front of us, quietly optimistic that our quest might be rewarded.

Then suddenly the ghostly form of a male hen harrier glided in low from the scrub across the reeds and dipped down out of sight.

Was that fleeting view the last we would see of it, we wondered?

As the light faded further, we spotted another hen harrier, also a male, its pale body clearly visible against the dark background. As it flew closer and landed amongst the sedges, we had excellent views and assumed this to be the same individual.

But soon afterwards the original bird rose from its landing site and slowly joined the second bird at its roost.

Quite why hen harriers roost on the ground is a bit of a mystery. Surely there is more danger there and they would be safer in a bush or tree?

As we somewhat reluctantly retraced our steps towards the exit from the fen a barn owl flew up from close to the board walk and began quartering the reedbeds and ditches nearby.

Another fenland ghost, pale and silent against the gathering gloom.

• Martin Walters is a Cambridge-based writer and naturalist.

Read more by visiting Martin’s author page

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