Great-tailed Grackle origins confirmed

The identification of the Pembrokeshire grackle of autumn 2023 has been confirmed as Great-tailed by DNA analysis, supporting in-field views.

Present at the coastal site of Nolton Haven from 25-29 October, the female grackle resided in the village car park and on surrounding area. The first record of the species for Britain, its sociable and confiding nature meant it proved a popular visitor during its five-day stay.

In addition, mtDNA sampling has shown that it belonged to one of the northern, central and eastern subspecies group. DNA is consistent with all subspecies except nelsoni (found across south-west United States and north-west Mexico) and graysoni (native to western Mexico). There are eight recognised subspecies. Both northern forms, prosopidicola and monsoni, are rapidly spreading northwards across the United States.

The Nolton Haven Great-tailed Grackle is the first record for Britain (Sam Viles).

Ship-assisted vagrant?

One of autumn 2023's major talking points, the grackle sparked fresh debate about the status of ship-assisted vagrants on the British list. With Britain's largest energy port, Milford Haven, just a short distance away, Nolton Haven is well situated to attract such ship-assisted birds. Oil tankers regularly anchor in St Brides Bay just off Nolton Haven while awaiting a berth.

Great-tailed Grackle has one of the most rapidly expanding populations of any North American bird. The species has extended its breeding range by more than 5,500% by moving north into North America between 1880 and 2000, following the spread of irrigated agriculture and urban development into the Great Plains and western US.

The species regularly takes advantage of ships to travel around, with multiple records from the Caribbean, South America and Hawaii. It has reached the Western Palearctic on at least five previous occasions, with records from France, Spain (two) and Canary Islands (two).

The stance of the British Ornithologists' Union Records Committee (BOURC) on ship-assisted birds means that the grackle is highly unlikely to be added to the British list, however. The BOURC's policy on ship assistance was "never meant to allow non-migratory species or port-to-port transportees to be admitted to the British List" and species have to be considered capable of reaching Britain without ship assistance. Neither of these criteria is likely to be met by Great-tailed Grackle.