Some bird content at last! This was in conventional birding parlance a “blocker removed”, or in my own particular speak a fallen long-term straggler. By the idiosyncratic criteria by which I judge such things the much sought lifer of this post was until now one of a group of seven most likely British list additions within my preferred travel range. But converting Aquatic Warbler is not that simple.
How so? Formerly an expected item of any national autumn passage, the potential to experience Aquatic Warbler (see here) has shrunk in parallel with its more recent status as Europe’s rarest migratory and only globally threatened passerine. This medium-sized Acrocephalus winters only in Senegal and arrives on it’s European breeding grounds in April. Those are largely confined to Poland and Belarus that hold around 70% of breeders, and there is a fragment population in Lithuania. The global population is now no more than 21,000 pairs. The species reverted from BBRC scarcity to rarity description level in 2014, since when the annual handful of English records have almost all been trapped and ringed individuals that were not seen again upon release.
It is dependence on a rather specialised and vulnerable wetland breeding habitat, prone to loss through drainage that has caused AW’s decline. This bird favours open, wet marshland with scattered bushes or trees, and has a requirement for sedge fen mires with a water depth of 5-10 cm. Conversion of coastal marshes to nature reserves, with habitat restructuring that does not suit AW, is said to have similarly contributed to reduced British sightings in recent times. Return passage begins in June with movement of juveniles such as today’s bird, south-west along the English coast peaking in late August and early September. In contrast with recent years the last two weeks have produced two twitchable items in south-east England. The first, also a juvenile at Landguard NNR in Suffolk on 30th Aug, stuck around for less than four hours in the afternoon and early evening.
When the second bird was reported inland in Sussex, to the north of Shoreham and the village of Upper Beeding (BN44 3WN – TQ 190113) on Sunday (10th), I assumed it’s stay would be similarly brief. But I really should have checked RBA on Monday morning. Instead I kicked myself after remembering to do so in the early afternoon, and found this must-see was still present and had been viewed at intervals to 12:40pm. That carelessness showed how out of the twitching habit I had become this year, but probably also that I must have been doing too much wildlife stuff alone again recently. And so I sought company for this venture, if it could be rescued.
As things transpired I was not the only Oxon birder to have been a little slow off the mark. Regular colleagues Adam and Ewan both said they were planning to go for the Aquatic on Tuesday’s first news, so we agreed to rendezvous near M40 Oxford services. Our quest was reported twice more through the afternoon and early evening, then again at dusk. With that my gut feeling grew that this was THE lifetime opportunity to convert an almost mythical straggler, and I was quietly confident of success.
Setting off at around 08:40 on 12th, we were re-assured by further RBA, Bird Guides and WhatsApp alerts at intervals through our 110 mile journey; then arrived on-site around 11 am. The location was a sloping bank of the River Adur below a narrow footpath through long grass and sedge (pictured below), along which up to 30 birders were spread out at intervals. Adam called the Aquatic Warbler soon after we arrived and I too noticed the brief movement into deep cover he was referring to.
At that everyone present converged upon the spot and almost total silence ensued for around 20 minutes as the gathering waited for the renowned skulker to re-emerge. When it did I saw clearly a second movement, then a thrill coursed through me upon picking out the Aquatic’s distinctive head pattern as it crept about low down in the habitat. That was mission accomplished personally, and as the bird flew up and away again everybody saw it so all the tension evaporated from the situation. Such to-ings and fro-ings continued for the rest of the morning and I was pleased with the repeated views gained.
I had expected a typical warbler twitch of staring for long periods at dense vegetation waiting for the quest to come out. But this bird was quite mobile around its adopted patch, though always fast moving. The stand out features of Aquatic Warbler are a quite bright yellowish-buff toning and the very strong head pattern with a thick, pale supercilium and whitish crown-stripe. Both were readily apparent as our bird moved around today. A flattened forehead and strong, pointed bill also mark the species out, while the upper parts are more heavily streaked than the familiar Sedge Warbler. Juvenile AW do not display streaking on the breast.
After an hour of activity on the bird’s part it went to deep cover again and was not seen for a similar period of time. So all three of us being satisfied with our experience we decided to leave. Neither myself or Adam, for whom this rarity was also a lifer, could quite believe how easily we had added it to our career lists in the end. But this instance was testimony to something I have faith in that sooner or later these things will turn up within range. It is just a matter of waiting, in this case for many years and I now feel hugely relieved and content to have converted such a prime target today. Aquatic Warbler is my 380th British bird.