Monday 20 May 2019

Otmoor Warblers 16th May 2019

Reed Warbler

May is the month when the numbers of breeding warblers on the RSPB's Otmoor reserve reach their zenith. Being a reserve primarily devoted to reeds and wet meadows and fringed with hedgerow it attracts three species of warbler that are my particular favourites, the Reed Warbler, the Sedge Warbler and the Common Whitethroat. All three are summer migrants, coming here to breed and then migrating to Africa to spend the winter. Reed and Sedge Warblers abound on the reserve. Common Whitethroats less so, due to less suitable habitat being available for them 

The Reed Warbler's  rhythmic, scratchy and jerky song, described by the original Handbook of British Birds as 'conversational' is first heard coming from low down in the dead reed stems of last year, that are only now being slowly superceded by this year's new growth. The new pointed leaves, rising up like grey green swords will eventually reach above the height of a man and conceal the warbler's nest, woven and slung like a basket between two stems of reed.

Sometimes the Reed Warbler will forsake the reed stems to sing in a small sallow or hawthorn adjacent to the reeds but never strays far from concealment in its favoured riparian habitat. Despite their loud song they are shy birds and if they sense you are looking at them or see you they will fall silent and drop down lower into the reeds, then move invisibly to another nearby reed to resume singing.

Sometimes you can track their progress through the reeds by the movement of individual stems and if you wait, see them sidle up and cling to another stem of reed and recommence their repetitive singing with one foot drawn up close to their body and the other extended below it in support,  That is if they do not see you first!

Reed Warblers conduct their lives mainly in secret,  right from their first  arrival, through courtship, nesting and finally departure to their winter home in Africa, predominantly remaining out of sight, preferring to skulk amongst the density of the reeds and waterside herbage. The first intimation of their arrival on Otmoor is when the males commence singing, having arrived  one May night, dropping from a night sky, unheralded and un-noticed until they proclaim their arrival by singing from first light the next morning. The urgency of Spring and to reproduce paramount.

Today I  tarried by the side of  the bridleway looking down on a water filled ditch to catch sight of a male Reed Warbler that was singing loudly and persistently from a small sallow bush. It was very close to me but at first it was invisible to my eyes and took some minutes to locate, perched well as it was inside the bush, its outline concealed and disrupted by the intervening stems and leaves, the latter casting sun dappled moving shadows across the tiny bird as they stirred in a gentle breeze.

However a brief movement, a change of position, betrayed the warbler's location and I could then see it reasonably well, perched and moving its head around as it sang, its uniformaly rich brown upperparts and underparts of cream buff with a noticeably white throat, unremarkable, but perfectly matched for a life of concealment in the reeds. I stood in the sun and waited patiently for it to gain confidence. As long as it was quiet on the bridleway, I did not move, and no one else came along the bridleway it would eventually reveal more and more of itself as it moved up a stem and nearer to the edge of the bush but never would it venture right into the open.

Its head appeared large as it sang lustily and continually, its rather long pointed bill held wide open showing orange inside and its white throat feathers distended with the effort of producing its song. For two hours I stood awaiting opportunities to take its picture and for all that time it was mainly singing. A few brief excursions along the water filled ditch interrupted the flow of sound but within a couple of minutes it would return to the favourite sallow and normal service would resume.

Reed Warblers on Otmoor are the main host of the parasitic Cuckoo and once the reeds are grown sufficiently and the nests constructed, the female Cuckoo will lay her single egg in a number of nests she has already been prospecting,  watching and waiting silently in a nearby bush or tree for days until the exact right time arrives to deposit her egg in the Reed Warbler's nest.

Sedge Warbler
The other warbler inhabitant of the riparian habitat on Otmoor is the Sedge Warbler, although it is disinclined to frequent purely reeds but more prefers the margins of wet ditches where there is plenty of rank undergrowth, brambles, bushes or other tangled vegetation near to the waterside. Where the Reed Warbler is shy and generally retiring, the Sedge Warbler is the opposite in the breeding season, singing loudly from an exposed perch at the top of a small bush or from a protruding stem of vegetation up which it ascends from cover to deliver its song, which is superficially similar to that of the Reed Warbler but lacks the rhythmic quality of that bird.

The Sedge Warbler's song, as befits its extrovert personality is loud, long  and wildly passionate, the notes coming in a chattering, buzzing, endless frenzy, seemingly at random and often incorporating the calls of other birds. Such is its exuberance at this time of year, the singer often takes flight, as if it cannot contain itself and, singing loudly, rises up into the air from its perch and then planes back down, with wings and tail spread wide to the same bush.

On Otmoor, one early morning, I discovered a particularly extrovert Sedge Warbler singing from the topmost spray of a briar by the pathway leading to the first screen. I watched a bravura performance as, again and again, it rose into the air singing before returning to the briar, always landing a little way further down in the bush but then quickly ascending to the topmost spray before taking to the air for another paragliding song flight.

They are attractive little  birds, slightly smaller than a  Reed Warbler and less uniform in colour, with long cream eyebrows, a cap of dark streaking and tawny upperparts streaked with black and darker brown, their undersides creamy white becoming buff on the flanks.

All over the reserve their frantic chattering songs come from  the hedgerows running by channels of water and wet ditches and the occasional excited bird floats down from a song flight as I wander along the paths of the reserve. The whole place is alive with the song of both Reed and Sedge Warblers and it is a delight to see the reserve now come alive and to be serenaded by these marvels of evolution that have made a perilous journey from far overseas to bring such pleasure to me and other visitors.

Common Whitethroat

So finally we come to the third warbler, the Common Whitethroat, which is less frequently encountered on the reserve at Otmoor, due to the fact that their preferred habitat, dry untended field borders, thickets and rough ground with tangled vegetation is less available. Mind you, where it is, then there will be found and heard the male Common Whitethroat singing his jaunty song - a short, lively jumble of cheery notes, repeated over and over and delivered from an exposed spray of vegetation or in a wild dancing song flight of pure ecstacy or so I like to think.

Along the same pathway where I described the extrovert Sedge Warbler singing, just  a little way further was a male Common Whitethroat behaving in exactly the same way. I do not know what it is about this path that persuades the warblers to be less fearful, maybe it is the constant procession of people walking to the first screen but whatever, it is a delight to be able to get so close to these birds and to freely watch them.

The whitethroat was singing from a hawthorn right by the track and at first I was circumspect, maintaining a distance so as to not alarm him as he sang. I edged closer and he did not budge. A bit closer yet and all he did was ascend higher up the spindly twig he was clinging to until he was outlined against the sky. He sang on, opening his bill wide and tilting his head upwards for maximum effect. Then a short period of silence followed before he sang again.

Emboldened by the whitethroat's lack of concern I walked closer still until I was almost underneath He looked down, curious but unafraid, cocking his head and then raised up his bill and sang to the heavens once more.

I was of no apparent concern to him and we shared a few moments together before he decided he would like to sing from another perch further down the pathway but less exposed. I walked past the whitethroat, now hidden inside a bramble and still he sang on as I left him.

I fell to thinking about the frankly incredible journey this bird had made to unknowingly charm me with his song and confiding nature. Some years ago its fantastic journeying was brought home to me when I encountered one spending its winter in Tanzania. Both of us so very far from home. The perils of, especially, a migrant bird's life are many and years ago when a young man I can remember one Spring awaiting the return of Common Whitethroats to my local study area in Surrey but they never came. Where there had been seven pairs of Common Whitethroats now there was none. It was 1969 and no one knew quite why they had failed to return not only to my small study area but as it transpired nationwide. A year later it was determined that severe drought in their wintering area in The Sahel  had decimated the wintering birds and it took some years for their numbers to recover

So we may call it a 'Common' Whitethroat but it can just as easily not be so and the whitethroat and birds in general are far less in number now than they were fifty years ago.

Locally too, we must never take the delights of Otmoor for granted, be they the warblers or any other of the splendid and scarce birds that occur there. Otmoor and its like provide a last remaining sanctuary in an increasingly hostile environment for the natural creatures that inhabit and share our planet.

We are indeed lucky to have them still but for how much longer?

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