British Birds Rarities Committee - Species Covered

Species Covered

Over 580 bird species have been recorded in Britain; some 250 have regular breeding or wintering populations, or are common migrants, and a further 50 are "scarce migrants". The BBRC assesses the remaining species. A list of the species the Committee assesses (known as "British Birds rarities", or "BB rarities" for short) is on its website, although the list has not been updated to account for the most recent changes. The Committee generally considers only the records of species rare enough to meet its criteria for inclusion on the BBRC rarities list, based on a numerical threshold. In addition to considering full species, records of some rare subspecies are considered and, in a few cases, the Committee considers indeterminate records (birds that belong to a pair or group of rare species that are particularly difficult to separate, such as frigatebirds or dowitchers).

The Committee keeps the list of species it considers under review and, from time to time, makes changes. These are usually because species have increased in frequency and no longer meet the numerical criteria for inclusion. A species is removed if it has more than 150 records in the preceding ten years, with ten or more in at least eight of those years. Different criteria were used in a review in 2006 (see below). There have been three major "purges" of species since the Committee's formation. The first was soon after the Committee's formation, in 1963, when 16 species were removed: Red-crested Pochard, Snow Goose, Pectoral Sandpiper, Mediterranean Gull, Sabine's Gull, Melodious Warbler, Icterine Warbler, Yellow-browed Warbler, Northern Goshawk, Golden Eagle, Red Kite, Kentish Plover, Crested Tit, Bearded Tit, Marsh Warbler and Dartford Warbler. Records of the last eight species had been considered only outside their "normal" British range (e.g. Crested Tits outside Scotland, and Red Kites outside Wales). The second was in 1982, when ten further species were removed: Cory's Shearwater, Purple Heron, White Stork, Buff-breasted Sandpiper, Richard's Pipit, Tawny Pipit, Savi's Warbler, Aquatic Warbler, Serin and Common Rosefinch. Savi's Warbler was re-admitted to the Committee's list in 1998, due to declining numbers of occurrences. Thirdly, in 2006, a further 17 species were dropped from the list: Ferruginous Duck, Wilson’s Petrel, Great White Egret, Black Kite, Red-footed Falcon, American Golden Plover, White-rumped Sandpiper, White-winged Black Tern, Alpine Swift, Red-rumped Swallow, Red-throated Pipit, Subalpine Warbler, Greenish Warbler, Dusky Warbler, Radde's Warbler, Arctic Redpoll and Rustic Bunting. Their selection was based on different criteria from those previously used: more than 200 records in Britain ever, and more than 100 occasions in the last decade.

Many other species and subspecies have been removed over the years: Cetti's Warbler (in 1976); Long-tailed Skua (in 1979); Common Crane and Ring-billed Gull (in 1987); Surf Scoter, Little Egret, European Bee-eater, Pallas's Warbler and Woodchat Shrike (in 1990); Green-winged Teal (in 1992); Ring-necked Duck, Short-toed Lark and Little Bunting (in 1993); White-tailed Eagle and Kumlien's Gull (in 1998); American Wigeon, Black-crowned Night Heron and Rose-coloured Starling (in 2001); and Black Brant (in 2005).

Until 2009, Parrot Crossbill was an anomaly, in that it was on the Committee's list of species, even though a breeding population exists in Scotland. In 2009, this species was removed, along with White-billed Diver and Cattle Egret.

Once removed, a species is classed as a "scarce migrant": British Birds publishes a separate annual report summarising the occurrence of these species, and the data is also presented on the Scarce Migrants website. In addition to Parrot Crossbill, four species, Cetti's Warbler, Little Egret, Long-tailed Skua and Mediterranean Gull, have become so common that they no longer qualify even as scarce migrants.