Have you seen an unfamiliar bird in the area that looks a bit on the tame side or seems too exotic to be British and you can't find it in your guide to British birds? This site may help. All the birds reliably recorded as being seen in Britain get a mention and all those that have not occurred here naturally are illustrated in the main content. If you have a rough idea of what family it is in take a look under the sections Ostrich to Pelicans, Vultures to Crows or Passerines, otherwise look down Category E and D.
This site is mainly about those birds that have occurred in the wild in Britain but that have had a little help along the way. Categories D and E are reserved for those species that had (or probably had) some help in arriving in Britain. For completeness, there is a full list of birds that got here by their own devices - see the British List.
Sometimes it is hard or impossible to know for sure, how a particular bird made it here. Where there is any doubt that an individual of a species not normally considered regular in Britain, has occurred naturally, but it cannot be definitively confirmed one way or another, category D comes into its own. Records on category D are regularly reconsidered with the intention of assigning them either to the British List or to category E.
As explained in more detail on the BOU page, category E is a list of the birds that have been seen in the wild in Britain but which do not form part of the "British List" because they got here with assistance from man and are not able to sustain themselves as a wild population. In some cases they have bred in the wild but not sustainably so.
Note that the BOU and this site only covers birds recorded in Britain i.e England, Scotland and Wales (and associated waters) and does not cover Ireland, Northern Ireland, the Isle of Man nor the Channel Isles.
To a large extent, species on category E are ignored and many go unreported. Birders' interest lies in the species that they can tick off and category E species don't count. "Escapes" are often derided and when they are reported to the county ornithological societies, they get a small mention at the back end of the species accounts in the annual reports. Species on category D could be there for some time or new information could come to light at any time which will determine the species' fate and it will be assigned to a 'permanent' category. (All species are reviewed as appropriate as new information comes to light).
The approach is quite different to that taken by botanists who record introduced species growing in the wild whether or not they are self-sustaining, though they are categorised accordingly where it is possible to do so, as established or casual. Of course there is a big difference between a small population of plants that might be around in the same place for several years and a Zebra Finch in a garden briefly (which may only have flown from next door's conservatory) but there is always a chance that it might meet up with a soulmate and establish a viable population and it is important that such events are documented.
Having responsibility for the British List, the BOURC is required to review those non-native species that may establish self-sustaining populations and be eligible for elevation to Category C. BOURC reviews available data relating to Category E* species (i.e. those species that have escaped or been released and have bred in the wild) to determine whether a species can be considered ‘self-sustaining’. BOURC, together with the Rare Breeding Birds Panel (RBBP), urges observers to submit records of non-native species to county recorders.
The hope is that this site will create more interest in category E species and that it will assist people (birders and non-birders alike) in identifying those birds that they come across and which don't occur in the field guides. The list is undoubtedly incomplete because of the birds that go unreported and because the BOU rely on birdwatchers to pass the sightings on to the county recorders and on the county recorders to report them to the BOU or RBBP.
The standard procedure for reporting any bird of interest including "escapes" is to submit the record to the county recorder but if you prefer to send it to me, preferably with a photo or description I will ensure the record is passed on to the recorder. I can't undertake to identify everything sent in but I'll do my best! email address is below.
The British List. https://www.bou.org.uk/british-list/
Non-native breeding birds in the UK, 2012-14. British Birds 110 February 2017.
I am very grateful to all who have made their images available via Creative Commons, without whom this site would have no illustrations