HOW TO SEE AN AQUATIC WARBLER
The possibility of seeing one of mainland Europe’s rarest birds, as it passes through Britain on its way to Senegal during autumn migration, is a real challenge. Not as a wind-blown vagrant, but as a species, following the process of its normal migration. These days it won’t be easy, but there are a few ways to maximise your chances. Firstly, it’s important to get the key identifying features clear, I’ve had a fleeting glimpse of a bird that’s got the pulse racing momentarily – in the field Aquatic Warblers can look very similar to Sedge Warbler. There are a suite of features that need to be checked to separate the two, and the best place to start is with the central crown stripe. Although Sedge Warblers can show the hint of a pale crown stripe, on Aquatic Warbler it’s well defined and obvious. Aquatic Warbler will also show a generally yellower base colouring to the body, lighter than the overall russet tones of Sedge, along with prominent black and yellow streaks on the back and a streaked rump. The lores, between the eye and the beak, should be pale, giving Aquatic Warbler an ‘open face’ expression. Ringers who’ve had Aquatic Warbler in the hand have assured me that a spikey or ragged looking end to the tail is a pro-aquatic feature and not just as a result of wet feathers clumping together, as has been suggested. The bird regularly perches in a characteristic way, acrobatically grabbing the stems of different plants in either foot.
Prominent back streaking and striped head
Aquatic Warbler Pale lores Streaks on breast
Yellowish plumage tones
Sedge Warbler Dark lores Adult has unstreaked breast
Warm plumage, less streaked