Caught by the River

Bardsey: The Attraction

6th May 2014

IMG_2233Photo: Ben Porter

Words: Jon Gower

Many species migrate at night, using elements of the night sky to navigate, literally the stars to guide them by. The light of the moon, too, can illuminate the land underneath these peregrinators. Gargantuan numbers of waders, warblers and thrushes fly purposefully through the dark along with a range of other species such as terns, larks, rails and starlings and these are all subject to being misdirected by the Enlli light, the Bardsey lighthouse, while seabirds such as storm petrels and shearwaters can also be drawn in to deadly effect. There have been rarities, too, with thrush nightingale and red-eyed vireo on the grim tally.

Historically a log was kept of such deaths. The lighthouse keepers’ notes were a useful source of information for visiting naturalists such as the appropriately named Eagle Clarke who analyzed the logs for the 1870s and 1880s. These deathly spectacles had a long history.

It takes a particular combination of circumstances to occasion an attraction: a prominent moon is usually required and then a rapid change in the weather. If conditions turns inclement the migrants seek out other sources of light. Birds are thus attracted by the light, which flashes every 15 seconds. Tonight is one such night.

One approaches the possibility with a mix of dread and fascination. The air is still, poised, inkily-black, but then the velvet is rent, as, seemingly, the night sky starts to rupture. The attraction has started.

The first birds to arrive are the jigsaw birds, random avian body parts caught in the slow stroboscope of the light. There are brief flashes of wing, quick glimpses of tail, dismembered birds’ heads with lit hints of beak and bill. Then, finally, when they’re fully mesmerized and are turning in helixes and spirals, trapped within the light’s ambit, you can recognize them as birds, the pieces now all fitting together, spectral white species fluttering through space.

They are all mesmerized like moths, as if drawn to a candle, except this one is equivalent to 90,000 candelas, a candela being a unit of light equivalent to one candle’s worth of luminosity. In they come, wings beating like metronomes.

In olden days lighthouses actually used candles as a light source, as they had a constant, consistent glow, though possessing very little individual power. One answer was to group them together, as was the case at the Eddystone lighthouse: in 1759 this sported a two-ring candelabrum holding two dozen candles. There were practical problems to using candles, not least the fact that the wicks had to be regularly snuffed and keepers – their nerves presumably jangling and on edge – were given reminders of wick-snuffing duties by a clock that struck every thirty minutes. These were eventually replaced but had their own drawbacks. Lamps burning oil, then sperm oil, then, ultimately vegetable oil produced soot and so the glass had to be cleaned all the time. A keeper’s lot was not a happy one.

To mitigate the deadly effects of the Enlli light, various devices have been employed over the years, such as floodlighting the tower to lessen the dazzle of the lamp, and setting roosting perches on top of the lantern, although these proved to be of limited effect. Initially, indeed, this idea was as much a curse as a benefit to the birds, as many were killed as a result of colliding with the lamp and surrounding buildings. But in 1978 a “false” lighthouse was built close to the original structure to draw birds away from the dangers and into the safer territory of the maritime heathland where many (up to 3,000) roost overnight before continuing on their long journeys. A system of illuminating bushes on the ground also proved to be efficacious.

The morning after an attractions can reveal a grim harvest of avian corpses, like an open-air homework exercise for taxidermists. The macabre haul may include no fewer than 120 dead grasshopper warblers, or “groppers” as they’re known in the birding trade. Enlli ranks as one of the best places to see this secretive skulking species, which is in decline as their wet habitats disappear. Their little gropper bodies weigh next to nothing in the palm of the hand, where their plumage, camouflage streaks and striations of olive and brown, is ineffably beautiful, if sadly so. Should you chance to sight a live one on migration its skulking habits might put you in mind of a mouse and in the hand it weighs much less than one, being not much more than nine grams. Such a small thing to fly so far.

The groppers aren’t the only fatalities. It has rained dead sedge warblers by the score, and a scattering of over a hundred willow warblers, littered over the short grass. There’s a plump wood pigeon, its dove-grey feathers hardening with rigor mortis into rigid slate, a half dozen sandwich terns, several black-tailed godwits, their long bills like kebab sticks and a tragic group of fallen whimbrel. Finally there’s one little egret, its startling white plumage reminding one of the sort of sombre lilies you find in a chapel of rest.

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