Changes to the British List (12 July 2024)
The British Ornithologists’ Union Records Committee (BOURC) has changed the category of a species on the British List.
The following species has been added to Category A of the British List:
Canada Warbler Cardellina canadensis
One, male, first-calendar-year, Stack Rocks, Castlemartin Ranges, Pembrokeshire, 23-25 September 2023.
Photo (right): Canada Warbler © Graham Jepson
This Canada Warbler Cardellina canadensis was discovered amidst an unprecedented arrival of North American landbirds in Britain in September 2023 with Alder Flycatcher Empidonax alnorum, Bobolink Dolichonyx oryzivorus, Magnolia Warbler Setophaga magnolia, and Bay-breasted Warbler Setophaga castanea all located within 36 km of Stack Rocks in the three days prior to its discovery. The cause of this unprecedented event was principally a well-timed and ideally attributed transatlantic storm system that carried many North American birds to Britain and Ireland (Brit. Birds 117: 292-307).
Canada Warbler breeds in central to southeast Canada and northeast, east, and north-central USA, and is highly migratory, with the bulk of the population wintering in northern South America along the eastern flank of the Andes (IOC World Bird List (v 14.1) http://www.worldbirdnames.org/).
The species was an anticipated vagrant to Britain with six previous transatlantic vagrants recorded from Iceland, Ireland and the Azores. The species is not known in captivity in Europe.
Canada Warbler becomes the nineteenth species (of eight genera) of migratory North American wood warbler Parulidae on the British List and a remarkable eleven of these were recorded in Britain during autumn-winter 2023-2024 (comprising 21 individuals).
Canada Warbler is monotypic and should be placed after Myrtle Warbler Setophaga coronata on the British List.
This change will be published as part of the BOURC’s 57th report due to be published in Ibis in January 2025. Upon publication of this change, the British List stands at 636 species (Category A = 618; Category B = 8; Category C = 10).