This blog on the intriguing yellow-browed warbler comes to you from John Bowler, RSPB Scotland's man on the Isle of Tiree.
This autumn (2016) has been a record-breaking year for sightings of yellow-browed warblers. Formerly a rare migrant to Britain, numbers of these tiny, brightly-marked warblers have been increasing here in recent years. They breed in Siberia and normally migrate south-eastwards to winter in the hill forests of tropical South-east Asia.
Each year, however, some birds accidentally head in exactly the opposite direction, passing westwards through Europe - leading to sporadic sightings on the east coast of Britain in September-October.
But this year, surprisingly high numbers started to appear on the east coast of England, particularly Yorkshire, in late September 2016, including a count of 132 birds at Flamborough Head. A second influx was focussed more on the Northern Isles and the Scottish east coast with day-count peaks of 72 on Fair Isle and 50 on North Ronaldsay.
Once they hit the eastern coasts of Scotland many birds started to work their way inland, appearing at a range of sites across the country including RSPB Scotland reserves such as Lochwinnoch and Baron’s Haugh. They were often seen feeding with goldcrests and tits on the sunlit edges of woodland.
Other birds filtered right through Scotland and some even reached the Hebrides, where a record 12 birds appeared on Tiree and up to 30 birds were seen on nearby Barra in a single day! Other sightings came in from RSPB Scotland The Oa on Islay, RSPB Scotland Oronsay and at RSPB Scotland Mull of Galloway.
The reason for this sudden surge in YBW sightings isn’t know, but as well as the autumnal passage of birds, a few are now also seen here on spring migration as they head NE back towards their Siberian breeding grounds. This would suggest that some at least of these westwards migrating birds are managing to find somewhere to successfully overwinter, perhaps in Spain or in West Africa.
One possible theory behind the increase is the ongoing rapid loss of their traditional wintering habitat in South-east Asia, as hill forests there are logged and cleared for agriculture.
Keep an eye out for them next spring and autumn, as this is certainly a bird to watch.
We found a dead one on our patio in late October this year - I think it might have collided with the glass of our conservatory. We're in central Scotland, on the border of Clackmannanshire and Kinross-shire.