16th August

We're sure that we've said it before, but some rarity records really do defy ready explanation so we'll just dine out on the fact that a Western Bonelli's Warbler graced the Obs garden today - the first record there for 38 years - rather than dwell on why it should have turned up on a north-westerly after a week of wholly unpromising Atlantic weather; although enjoyed by those who were on hand to see it at close quarters after it had turned up in a mist-net, it proved far from easy to catch up with after release and remained extremely elusive for the rest of the day. The rest of the day's events paled by comparison, with grounded migrants a less than conspicuous feature after a very clear night. The Bill area did come up with a fair bit of visible passage, including 26 Cormorants heading in various directions, 11 Tree Pipits, 3 tardy Swifts and several hundred more departing Lesser Black-backed Gulls, but singles of Lesser Whitethroat, Pied Flycatcher and Spotted Flycatcher amongst a handful of Sedge Warblers and Willow Warblers provided the only real interest on the ground; elsewhere a Little Egret passed over at Blacknor. Seawatching at the Bill came up with 33 Common Scoter, 16 Manx Shearwaters, 2 Sanderling and a Tufted Duck.

The Obs moth-traps were a little busier than might have been expected on a cool, clear night, but singles of Vagrant Piercer and Delicate provided the best of the immigrant interest. By day, Hummingbird Hawk-moths and Painted Ladies were both more conspicuous than in recent days, with several of both in the Obs garden and at other sites around the island.

Western Bonelli's Warbler - Portland Bill, 16th August 2014 © Joe Stockwell (upper) and Martin Cade (lower)
...with the bonelli's warbler species-pair these days considered almost inseparable on plumage features alone it was perhaps fortuitous that this individual should be first found in a mist-net and straight away reveal itself to possess a wing-formula seemingly typical of Western: the tip of the 2nd primary (the uppermost feather in the photos below) fell between the tips of the 6th and 7th (longer in Eastern, usually falling between the 5th and 6th), and the 6th primary was clearly emarginated (less clear/absent in Eastern). Eventually the bird was heard to call on several occasions - a disyllabic note (vaguely Willow Warbler-like on our one hearing at some distance) quite unlike the chipping call of Eastern.