Saturday 12 September 2020

Marsh Warbler Surprise June 2020

A birding colleague called me back in June and suggested we meet to go and see a Marsh Warbler that had been singing non stop for up to a week. This was an invitation too good to miss as I had not seen or heard a Marsh Warbler in Britain since the discovery of one in 2009 on the RSPB's reserve at Otmoor, in my home county of Oxfordshire .

We rendezvoused extra early at 5.00am. The reason for meeting so early was to be there before any other birders or members of the general public with an interest arrived, as this made the bird shy and less likely to sing in the open. 

We walked for half a mile on a footpath, the air was still and beside us were fields overlain by a light mist as the sun had yet to warm the land sufficiently. All around us was resonating with bird song. Sedge Warblers had commandeered bushes to deliver their irrepressible crazed song, occasionally flying up into the air in a frenzy before dropping back down onto their particular bush. The monotonous notes that constitute a Reed Bunting's song could also be heard, the singing bird no more than a black silhouette at the top of a distant bush, the bird but an outline set against a rising sun. A Grasshopper Warbler reeled, a whirring ticker tape of dry notes delivered for long periods at high speed, the sound coming in varying volume as the hidden bird turned its head from side to side.

Coming to the spot where the Marsh Warbler had been singing for every day up to now, a ditch lush with a burgeoning summer vegetation of reeds, sedge and long grasses, silence greeted us where there should have been a distinctive loud song, mimicking many other birds, that constitutes a Marsh Warbler's repertoire. Confounded, we were at a loss as to what to do.

We speculated the bird had possibly moved on but thought it unlikely as it had been singing lustily for every day it had been here and looked like it was set to make this small area its summer home. Perhaps it  had been caught unawares by a Sparrowhawk, a not unprecedented occurr
ence for birds out of their normal range but again we dismissed this notion. My colleague suggested that maybe it had found a mate and as a consequence had ceased singing.We regarded this as far too fanciful to be possible.

Both of us stood for a while and looked to where the warbler had been singing just yesterday evening but there was no activity. As we  stood on the path four cuckoos pursued each other, flying above us with distinctive shallow fast wingbeats and away across the fields and trees. A Barn Owl flew its wavering course at the far edge of a large field.

Some minutes later we saw an acrocephalus warbler in a small bush behind the ditch where the Marsh Warbler had been seen to sing. Could this be it and it was just not singing? It was impossible to be certain as a Reed Warbler and Marsh Warbler are virtually identical unless you get close definitive views of the diagnostic differences, which are marginal at the best of times. The song usually provides the best form of identification but we were denied that.

We waited to see if the bird returned, having flown off. It did or at least a very similar bird did and then to our surprise another joined it and the two birds flew down into a patch of reeds and sedge and disappeared. 'They must be Reed Warblers surely' I said. Five minutes later the two birds flew out of the reeds and away. We waited and thought we heard a snatch of Marsh Warbler song but it was too brief to be totally certain.

Ten minutes later o
ne of the birds returned and it was carrying nest material that looked like the fluff from reedmace! It sat in a bush for a few seconds, checking all was clear and then flew to the same spot that the two birds had visited just minutes ago.

So we had probably heard a Marsh Warbler sing briefly and now seen another Marsh or Reed Warbler bringing nest material. Could the totally unexpected and unprecedented have happened and the singing male Marsh Warbler had attracted a mate? There was only one way to find out and that was to try and get photographic evidence. Both of us had cameras and set about the task which was none too easy as the birds, now regularly visiting the nest site together, were only briefly on view before descending into the reeds. Standing on the path there was a lot of obscuring vegetation between us and the nest site and it was very difficult to get a clear line of sight.

We both frustrated ourselves with failed attempts at recording the birds but slowly a rhythm developed as we saw that each time the bird returned with nest material it was accompanied by its mate. A well known local birder arrived and we informed him of our discovery and our suspicions that the Marsh Warblers were breeding. He was amazed as he had come complete with a parabolic reflector to record the Marsh Warbler singing and was now presented with the completely different and exciting prospect of witnessing a first ever breeding of Marsh Warblers in .......................

He asked us if we could try to get definitive photos in order to identify that the two birds were indeed Marsh Warblers.We informed him that it was not for lack of trying but we would persist. He also suggested that if they were indeed Marsh Warblers we should get a photo of the bird, presumably the female, bringing nest material.This would contribute to conclusive proof of breeding.

I took a lot of photos of the female. She did all the work while being closely accompanied by the male, who at first went with her to the nest site but latterly remained in a bush awaiting her departure from the site, when both would hurry away to some nearby trees.

The male Marsh Warbler
Finally, after many attempts I managed to get an image of the female with some straw or grass in her bill before she flew down into the reeds. So we at least had that recorded.

Female Marsh Warbler with nest material
Both of us took many photos hoping some of them would be suitably clear and definitive, when examined later, to indicate that both birds were Marsh Warblers. Although it was unlikely, we could not discount the male Marsh Warbler being paired with a female Reed Warbler. Such a situation has, I believe, been recorded before.

Towards the end of our observation the male Marsh Warbler perched on some reed stems and sang, not for long but enough to, without doubt, identify itself as a Marsh Warbler. 

Back home I examined my photos and they showed that both birds were indeed Marsh Warblers and this constituted the first record of Marsh Warblers breeding in .................

We were sworn to secrecy until the young fledged, hence the delay in posting this on my blog and my circumspection about revealing the location, for which I ask your indulgence.What a pleasant surprise to go from my initial disappointment of believing I had made a fruitless journey only to make an exciting and historical discovery with my equally delighted colleague.


21st July 2020

Today we returned to where the warblers had bred knowing that they had been successful and their young had left the nest a few days earlier and were hidden deep in the luxuriant vegetation that now occupied and all but subsumed the wide damp ditch in which they had been born and raised.

The parent birds were hard at work delivering food, both adults visiting their young scattered along a short stretch of the ditch either side of the nest site. The adults never showed themselves for more than a few seconds, forever flying low and using the cover of the vegetation to hide their movements, secretive and quite rightly, unwilling to disclose the whereabouts of their precious and vulnerable young.

In four hours of observation there were only two opportunities where the adult bird showed itself for more than a few seconds and enabled me to take a photograph. I did see two of the juveniles but only fleetingly as we caught them by surprise, in the open, just as we arrived. After that we never saw them again but knew approximately where they were by following the feeding visits of their parents. 

One of the adult Marsh Warblers searching the reeds and catching a Banded Demoiselle
damselfly to take to its young

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