Changes to the British List (13 January 2020)
The British Ornithologists’ Union Records Committee (BOURC) has added the following subspecies to the British List:
‘Taiga’ Merlin Falco columbarius columbarius
Second-calendar-year or older, Burnside, Scrabster, Caithness, 3–18 February 2018 (photo right: 3 February 2018 © Nina O’Hanlon).
Published material indicates that the described tail-banding of this individual is diagnostic for various Nearctic subspecies of Merlin, including nominate F. c. columbarius. Another Nearctic subspecies F. c. richardsonii was excluded because of the dark colour of the upperparts of the Caithness bird. F. c. columbarius is also the more likely trans-Atlantic vagrant, based on its eastern North American distribution and migration patterns.
The probability of this individual being an escape from captivity was judged to be very low, and the subspecies has been recorded previously elsewhere in the Western Palearctic as a trans-Atlantic vagrant. Thus the subspecies was accepted to Category A.
Merlin is polytypic, breeding across the Palearctic and Nearctic regions, with northern populations moving south during winter.
‘North American’ Horned Lark Eremophila alpestris (alpestris/praticola/hoyti)
First-calendar-year or older, Askernish (Aisgernis), South Uist (Uibhist a Deas), Outer Hebrides, 9-14 October 2014 (photographed).
Plumage features indicate that the Outer Hebrides individual was one of the North American subspecies of Horned Lark, and not a European Shore Lark E. a. flava. Key features included the reduced amount of yellow in the ear coverts and face which distinguishes such birds from E. a. flava.
The probability of this individual being an escape from captivity was judged to be very low, and the subspecies group has been recorded previously elsewhere in the Western Palearctic as a trans-Atlantic vagrant.
Of the many North American subspecies, three have a north-east distribution and display movements between breeding and non-breeding areas: E. a alpestris, E. a. praticola and E. a. hoyti.
Of these only nominate E. a. alpestris has an east Canadian breeding range and makes large movements along the east coast to winter in south-east USA, and so seems the most likely as a trans-Atlantic vagrant. However, E. a. praticola and E. a. hoyti also have an eastern range and so cannot be discounted with certainty. Thus the subspecies group (alpestris/praticola/hoyti) was accepted to Category A.
Horned Lark is polytypic, breeding across North America south to Central and northern South America. Some populations, particularly in the north of the range, are migratory with significant movements between summer breeding and winter areas; others are either resident or partially migratory. Shore Lark is also a polytypic breeding species across the Palearctic region.
Other decisions
Great Cormorant Phalacrocorax carbo sinensis
New first record: male, adult, Orkney, 30 March 1873, specimen at National Museums Scotland, Edinburgh, accession number NMS.Z 1888.84.162 (Scott. Birds 38: 136-138) is accepted as the first British record.
A specimen of an adult female reported to be P. c. sinensis from Christchurch, Dorset, collected in February 1873, with the specimen held at the Natural History Museum, Tring, with the accession number NHMUK 1873.12.3.31 (Ibis 72: 244-247) was re-identified during this review as nominate subspecies P. c. carbo.
Cormorant is polytypic, with P. c. sinensis breeding across Europe and the Palearctic region to China; and nominate P. c. carbo, from north-west Europe to Atlantic North America.
These changes will be published as part of the BOURC’s 51th report due to be published in Ibis in January 2021.
Upon publication of these changes, the British List remains at 620 species (Category A = 602; Category B = 8; Category C = 10).