British Ornithologists’ Union Records Committee (BOURC): 56th Report (January 2024)

Abstract

This report covers the period October 2022 to September 2023. The 55th Report appeared in Ibis 165: 360–363.

The following changes have been made to the British List.

The following subspecies are added to the British List in accordance with earlier iterations of the IOC World Bird List (https://www.worldbirdnames.org):

The Eider subspecies Somateria mollissima faeroeensis is recognized as a valid taxon by the IOC, with birds breeding in Shetland, Orkney and the Outer Hebrides apparently pertaining to this taxon, with the new annotation being:

The release of versions 13.1 and 13.2 of the IOC World Bird List results in a number of changes to the British List. These include:

Tibetan Sand Plover Charadrius atrifrons is split from Lesser Sand Plover C. mongolus (re-named Siberian Sand Plover) based on phenotypic differences and phylogenetic analysis. The new annotation is:

Historically, bird taxonomy was largely based on morphology, but in recent decades molecular genetic and bioacoustic data have been used to refine species limits, resulting in the recognition of many new species-level taxa, both through the elevation of subspecies to species status and through the identification and designation of new taxonomic units. Many of these new species are difficult to identify in the field and necessitate a pragmatic approach from rarities committees. For example, if systematic revisions result in a split leaving a restricted range resident species with limited or no long-distance vagrancy potential and a highly-migratory sister species with high vagrancy potential then the burden of assessment proof need not consider elimination of the resident taxon if this is difficult or impossible under field conditions (and if the escape potential of this taxon is also negligible) e.g. the recent splits of Himalayan Bluetail Tarsiger rufilatus from Red-flanked Bluetail T. cyanurus and Salim Ali's Swift Apus salimalii, Blyth's Swift A. leuconyx, and Cook's Swift A. cooki from Pacific Swift A. pacificus. Obviously, if identification is possible by obtaining a DNA sample or through acoustic recordings then confirmation is desirable, but the absence of these need not be a barrier to formal acceptance to the British List. Therefore, BOURC will take a pragmatic approach to any such species pairing or groups on a case-by-case basis, where it is overwhelmingly likely that a record pertains to one cryptic species and not others; when this is not the case, the species group will be added to Appendix 4 (Ibis 164: 909–910).

Traditionally, records of vagrants considered by rarities committees will have been found and identified in the field by human observers supplemented by field notes; historically often the specimen of the bird would have been provided too. In recent decades submissions have usually also included supporting ‘rich media’ in the form of photographic images and/or video, and acoustic recordings. Rich media can be invaluable in many cases in establishing the identification beyond doubt and indeed a number of recent British firsts involved birds re-identified from images posted online. Advances in technology means that autonomous sensors are now deployed to monitor bird populations in space and time. These include tracking devices to follow the movements of individual birds as well as passive acoustic monitoring to record bird calls diurnally and nocturnally, and the use of camera traps to visually survey birds. Diligent observers have even discovered rarities browsing webcams from insular vagrant traps in North America. Autonomous tracking devices have resulted in interesting discoveries of vagrancy events, for example the satellite tracking of raptors and seabirds has resulted in national first records in many countries globally. The BOURC anticipates consideration of a recent published record of an individual of the winter-breeding population of Madeiran Storm Petrel Hydrobates castro (the formally undescribed ‘Grant's Storm Petrel’) tracked with a 1-g Pathtrack GPS-tag (Brit. Birds 116: 232–324) as a British first record. Previous British records of this superspecies failed to differentiate between Madeiran Storm Petrel H. castro, Monteiro's Storm Petrel H. monteiroi and Cape Verde Storm Petrel H. jabejabe with the species group therefore assigned to Appendix 4 of the British List (Ibis 164: 909–910). Consideration of the circumstances of records without a human observer by BOURC will occur on a case-by-case basis, and submissions will require as much observation metadata as possible including, if available, a voucher image of the tagged individual to confirm species identification. Further, avian tracking tools vary in their geospatial accuracy with data varying between the very coarse scale light-level geolocator which may not be able to definitively establish the presence of an individual within a national boundary, to the very fine-grained position information provided by GPS. Therefore, all of these factors will be taken in consideration by BOURC when judging such records.

Following the addition of Kelp Gull, Least Bittern and Sulphur-bellied Warbler, the British List increases to 633 species.

Species in Category D and Category E form no part of the British List.

All the changes listed here can be seen in updated versions of the British List, both in Excel and simple list formats, at www.bou.org.uk/british-list/

The BOU website is regularly updated and contains the latest version of the British List incorporating IOC taxonomic changes, announcements and the most recent Committee reports. However, the website is for information purposes only and is not an official document or part of the permanent record. Announcements of changes to the British List do not come into official effect until published in a Committee Report, such as this, in Ibis.

Batty, C. & McInerny, C.J. 2022. The Ross's Goose in Britain. Brit. Birds 115: 12–25.

McInerny, C.J. & McGowan, R.Y. 2023. Scottish Birds Records Committee report on rare birds in Scotland, 2021. Scott. Birds 43: 99–117.

McInerny C.J., McGowan, R.Y., Clark, J.M., Moody, M.P. & Harrop, A.H.J. 2023. An apparent 19th Century record of Scopoli's Shearwater in Hampshire. Brit. Birds 116: 222–227.

McInerny C.J., Sellers, R.M. & McGowan, R.Y. 2023. A review of early historical records of Collared Pratincole Glareola pratincola in Britain. Brit. Birds In Press.

Alexander Lees (Chairman) (from July 2023)

Chris McInerny (Secretary)

James Gilroy (Chairman) (to June 2023)

Leila Walker (ex officio non-voting member; BOU Chief Operations Officer)

Ross Ahmed (from July 2023)

Chris Batty

Pierre-André Crochet

Paul French (ex officio; BBRC Representative)

Mark Golley

Mark Thomas

Steve Dudley (Category C)

Bob McGowan (Museums)

Keith Naylor (Historical Records)