Saturday, 1 June 2013

Locustella Overdrive

6AM. I couldn’t tell if the shiver that ran through me was from tiredness or chill. For the first of June, this was a pitifully grey morning. Through the murk Lakenheath Fen sang with a cacophony of Reed Warblers, Cetti’s Warblers and Cuckoo echoing through the stands of poplar trees. Colour was sapped from the scene but summer’s deep vegetation wafted through a fragrant reminder of the season. We walked west on the track that runs through the waist-high marsh before abruptly stopping at west wood. The song of a Locustella warbler filled the air.

I hadn’t done my research, I’ll admit that now. If I had I’d probably have recognised that this wasn’t the song of a Savi’s Warbler, our target, and that the real twitch was about 200 metres further down the track. But I was lazy last night, the car park was pretty empty and here was a small knot of people looking through scopes. There was a whisper of Savi’s and confused directions were in the air. I get offered a look through a scope ‘at the bird’: a dark Locustella warbler singing from a reed-head on a nearby bank. And now excitement was in the air.

Locustella warblers all sing with a variation upon a drily unmelodic, insect-like churr. They don’t sing in repeated phrases but two quick notes, repeated with mechanical speed and frequency, ceaselessly for minutes on end. It’s an uncanny dirge because they rotate their heads whilst they sing, thus ‘throwing’ the song and making it incredibly difficult to pick out which patch of reeds or bush the sound is coming from. In the poor light we could make out a dark Locustella, throwing a song that sounded wrong. I find it hard to recognise species by song but I can tell what’s different and this didn’t sound typical to me. The other birders were very happy by this point. As the light improved it flitted from bush to bush before stepping up for staggering views as it sung. Facing us, we could make out the dirty brown but plain underparts, and the wide open bill from which the torrent of noise flooded out. And then it flitted around and showed a dirty brown streaked back.

The crowd’s assumption was still Savi’s. No dissenting words, so I whisper to dad: ‘I thought they were unstreaked…’ and curse my lack of preparation, assuming I’m in the wrong. Other birders drift off, happy with their Savi’s. I resort to googling from my phone to have my suspicions confirmed: we’d been had. At the same time a photographer ambles down the track and tells us that the Savi’s is actually about two hundred metres further on…
It was half seven by the time we’d found the actual twitch. It was fully light by now but our early morning advantage was gone – from here I expected the bird to get less active, the light worse and the crowd to swell, but after about fifteen minutes of Reed Warbler false alarms, a different Locustella song emerges from the reeds. Not long after, shimmying up a reed-head was the singing warbler. The position was the same as the Grasshopper Warbler before but in large. The bill catches attention first for appearing to be drawn on in marker pen: big, thick and black. It’s a style that seems to influence the whole cartoon Reed Warbler appearance of the Savi’s Warbler: bigger, thicker, darker. It sang for a minute before descending back into the depths of the reedbed. It’s quite hard to imagine how anyone could confuse a Grasshopper Warbler for it, but it’s been proven many times how hard it is to look with an open mind after you’ve been told you’ve found what you were looking for.

We didn’t see the Savi’s again: we could only cope with fifteen minutes more in the company of the crowd, in which time we manage to see three Bitterns have a hormonally-charged chase high over the reedbed. We traipse around the rest of the quiet reserve. A Cuckoo flew over: all lanky limbs and elastic wingbeats, and a handful of Swifts hurtled low over the cold reserve. By the time we’d walked around the riverbank back to the beginning of the reserve trails, we’d still not seen a Barn Owl.

‘As if we’ve not seen a Barn Owl’, I said.
‘Where’s the Barn Owl?’ replied dad, furrowed brow.
‘We’ve not seen one’, I say.

I raise my binoculars. Quartering the other side of the river was a Barn Owl as white as the sky.

Strange day.

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