All birds that are BOU Category A, B or C that have been recorded (and accepted by the relevant committee) are listed below. Species that have occurred in the current report are shown in green. If they did not occur in 2020 the year they were last accepted in Cornwall is given. Subspecies accepted in Cornwall are shown in italics, indented and are listed under the main species name.
The various letters and symbols accompanying the species names refer to their status on a county and national level as outlined below:

National Rarities as defined by BBRC are indicated by †

Cornwall description species:

• (F) FULL DESCRIPTION – Cornwall rarity, all records required, with full supporting notes and photographs
• (P) PARTIAL DESCRIPTION – All records required with brief supporting notes and photographs, or the names of two other known observers
• (N) NO DESCRIPTION – All records required but descriptions not normally necessary unless for a record outside the expected location, date or count for that species

BOU species categories (see http://www.bou.org.uk/british-list/ for full details):

• A  – Recorded in an apparently natural state at least once since 1950
• B  – Species recorded in an apparently natural state at least once between 1 January 1800 and 31 December 1949, but have not been recorded subsequently
• C  – Species that, although introduced, now derive from the resulting self-sustaining populations.
• C1 – Naturalized introduced species: species that have occurred only as a result of introduction (e.g. Egyptian Goose)
• C2 – Naturalized established species: species with established populations resulting from introduction by man, but which also occur in an apparently natural state (e.g. Greylag Goose)
• C3 – Naturalized re-established species: species with populations successfully re-established by man in areas of former occurrence (e.g. Red Kite)
• C4 – Naturalized feral species: domesticated species with populations established in the wild (e.g. Rock Dove/Feral Pigeon)
• C5 – Vagrant naturalized species: species from established naturalized populations abroad (e.g. possibly some Ruddy Shelduck occurring in Britain). There are currently no species in category C5.
• C6 – Former naturalized species: species formerly placed in C1 whose naturalized populations are either no longer self-sustaining or are considered extinct (e.g. Lady Amherst’s Pheasant)
• D – Species that would otherwise appear in Category A except that there is reasonable doubt that they have ever occurred in a natural state
• E – Species recorded as introductions, human-assisted transportees or escapees from captivity and whose breeding populations (if any) are thought not to be self-sustaining. Species in Category E that have bred in the wild in Britain are designated as E*.

# Species on the official British List but not accepted as having occurred in a genuine wild state in Cornwall.