The Wildlifewriter: The Puzzle of Portmore Lough

The view from the lower hide is oddly familiar, yet rather strange. We overlook a freshwater lake surrounded by low-lying wetlands of fen carr and unimproved grassland. Summer waterfowl chase each other around the shoreline, while nesting terns and gulls are busy on a couple of nearby nest rafts. The sky is big and open, though a few birch and alder trees stand to our left. It's sunny and getting rather hot out there. But where are we? It could be Cambridgeshire or somewhere else in East Anglia, or even northern Germany. But listen... from beyond the high ground on the far side of the lake, the sound of racing motorcycle engines drifts down from the roads where morning Qualifying is already under way. Behind the hide, a squadron of military transport helicopters is wheeling down from an air force station towards the army barracks about twelve miles to the south. Wherever we are, it's a long way from Norfolk...

This is the Portmore Lough nature reserve in Northern Ireland, and you can bring me here to die.

Gulls and terns at Portmore Lough
(c) Wildlifewriter 2013

On the first sunny weekend of the whole summer, more than 20,000 visitors have arrived at the Oxford Island centre down the road, and their car parks are already overflowing – yet here we have the place to ourselves. Like most fenlands it's remote and difficult to access, although RSPB who have the management of the reserve area, have done a lot of work on paths and boardwalks since last year. Wellington boots are no longer obligatory. This type of wetland habitat is rare in Ireland but, where it exists, Nature takes full advantage. As biodiversity hotspots go, the place is almost incandescent: 317 species of insects at the last count, including bembidion clarki and a colony of rhinoceros beetles found nowhere else. Tree sparrows Passer montanus are nesting in boxes by the upper boardwalk. On the water, common terns are still incubating: testament to the late spring and their difficult migration this year, but the black-headed gull chicks have hatched over the weekend. They stagger among the tern nests, trying to find their feet and avoid being pecked at the same time. The project to increase lapwing breeding is also paying off and numbers are already up on last year.

Anything could appear here – and usually does, if you time it right. In spring and autumn, the big-ticket items are passing through: ospreys are regular visitors, though none have stayed to nest as yet. It would be an ideal place for them, with perch and pike abundant in the water and minimal human activity. Short-eared owls feel secure enough to hunt in broad daylight and, after dark, rare Daubenton's bats are active along the gullies and hedgerows. By winter, internationally important numbers of wildfowl roost overnight on the lough, safe from ground predators and humans disturbance. Whooper swans and some Bewick's will be here, with gadwall and pochard occupying the cheap seats at the front.

Up at the observation platform, local birder Paul Toner is catching a few afternoon

Juv female marsh harrier, Portmore Lough, Jan 2012
(c) Ed O'Hara

rays and we stop to ask what the “craik” is: in January last year, Paul, Ed O'Hara and the local group recorded (and photographed) marsh harriers on the reserve – a good tick anywhere but big potatoes for Ireland where they are never regular. We talk about ospreys again, and the issues about getting planning permission for a nest platform. Bureaucracy will have its due course, and nothing will speed it up. A few other enthusiasts wander in and, as ever, the conversation turns to the mystery of the Lough itself: why is it here, and why is this place so different from the surrounding landscape?

No-one knows. The lake itself is almost circular, which is an odd thing for a natural formation. It is certainly not glacial in origin, as existing textbooks claim.

Google Earth 2013

Old maps and written descriptions from the sixteenth century make no mention of it, and recent core samples have confirmed that there was no large body of water present at that time, yet one seems have appeared - almost overnight - around the mid 1580's. It's even been suggested (quite seriously) that an airburst meteorite might have exploded there, excavating the circular depression in which Portmore now lies, but leaving no physical trace of what would surely have been a spectacular event at the time...

You'd think someone would have noticed.