Population & Distribution
Occurrence in the Great Britain
The list of species officially recorded in Great Britain is maintained by the British Ornithologists' Union. In 1997, the categorisation was revised to assist protection under national wildlife legislation, especially of naturalised species. Categories A, B and C are included in the British list, Categories D and E are not.
A Species that have been recorded in an apparently natural state at least once since 1 January 1950.
B Species that were 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 Alopochen aegyptiacus
- 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 Anser anser.
- C3 Naturalized re-established species - species with populations successfully re-established by Man in areas of former occurrence, e.g. Red Kite Milvus milvus.
- C4 Naturalized feral species - domesticated species with populations established in the wild, e.g. Feral Pigeon Columba livia.
- C5 Vagrant naturalized species - species from established naturalized populations abroad, e.g. possibly some Ruddy Shelduck Tadorna ferruginea 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 Chrysolophus amherstiae.
D Species that would otherwise appear in Category A except that there is reasonable doubt that they have ever occurred in a natural state. Species placed in Category D only form no part of the British List, and are not included in the species totals.
E Species that have been 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*. Category E species form no part of the British List (unless already included within Categories A, B or C).
F Records of bird species recorded before 1800.Full details are available here. There are currently (31/08/10) 592 species on the British list (i.e. in Categories A,B,C).
United Kingdom Population Size
Population sizes are given for three distinct periods: Summer (the breeding season), Winter and Passage (generally Autumn when numbers are greater).
Breeding population sizes are mostly taken from Musgrove et al. (2013), which represents the work of the Avian Population Estimates Panel and refers specifically to Great Britain (i.e. excluding Northern Ireland and the Isle of Man). An indication of the reliability of the estimate is given on a three point scale (Good, Moderate or Poor). For an earlier assessment of population sizes see Baker et al. (2006).
Winter population sizes are also taken from Musgrove et al. (2013). For waders and waterfowl these are the mean annual peak count from the Wetland Bird Survey (WeBS). Estimates for a few other species are given where the species occurs mostly in winter and a reaonably reliable estimate of population size is available. For selected (mostly sedentary) species we have made a rough guess at the peak winter population size by taking the breeding population size and adding a fraction (number of broods * brood size * juvenile survival) for the years productivity; these figures are intended as a rough guide and should be used with extreme caution!
Passage population sizes are taken from Fraser & Rogers (2001) and represent the annual mean number of birds reported over the period 1990-1999. These figures rely on records submitted to county bird reports, so are likely to underestimate the true total somewhat. In general, spring and autumn passage are not equal in size, with the autumn passage of birds usually being much larger and so contributing most to the total. These estimates refer just to Britain.
We have provided links to the BirdTrends Report, which provides annually updated information on population trends for the most common species occurring in Britain. Where appropriate we also provide links to regional trends from the Breeding Bird Survey and the BTO's distribution atlases.
For most species we give the date of the first documented occurrence in Britain. The first systematic attempt to provide a verified list of birds occurring in Britain was by William Turner in 1544 with his Avium praecipuarum quarum apud Plinium et Aristotlem mentio est brevis & succinta historia [A short and succinct history of the principal birds noted by Pliny and Aristotle]. For records of species before this we give the first century for which documentary evidence is available of the species occurring in Britain; clearly most species would have been present earlier, though some (such as the Willow Tit may not have been recognised). For species occurring after this, when ornithological publications were much commoner, we give the date of the first published record, and an indication of the source where possible. These details are largely based on Bircham (2007, in turn based on the work of James Fisher). For species recorded for the first time more recently (particularly since the 1950s) details of the first sighting are usually published (primarily in British Birds). In this case, we give the county and year of first sighting, together with the original publication (or a subsequent paper if this substantially revises the original record, for example Moustached Warbler). Where a species has been indentified from fossil evidence we note the earliest period from which evidence comes, taken from Bircham (2007) based on the work of Harrison.
The conservation status of birds occurring in Britain is regularly asssesed, with populations being placed on one of three lists: Red, Amber or Green (Eaton et al. 2009). Red List species are those which are: Globally Threatened, whose population or range has declined rapidly in recent years, or that have declined historically and not shown a substantial recent recovery. Amber List species are those which have an unfavourable conservation status in Europe, whose population or range has declined moderately in recent years or those whose population has declined historically but made a substantial recent recovery. It also includes rare breeders and those for which the U.K. holds internationally important or localised populations. Species on the Green List fulfil none of the above criteria and are of least conservation concern. For more details on the criteria and how they were applied, please click here. The full paper, published in British Birds (102:296-341) can be viewed here. Fifty-two species have been placed on the Red List and 126 on the Amber List. The remaining 68 species are Green listed.
For the first time the conservation status of races has been assessed. There is much less knowledge on the occurrence and status of races in Britain, so these assesments should be regarded as provisional and the stimulus for future research. Only races of polytypic species were considered. Of the 226 races considered 48 were Red-listed, 117 Amber-listed and 61 Green-listed (in most cases (78%) listing was similar to that of the parent species, in 30 cases the assessment was worse and in 19 better). Note the categories of "international" and "European" concern are based on assessments specifically carried out for this exercise, for full details, click here.
UK BAP priority species and habitats were those that were identified as being the most threatened and requiring conservation action under the UK Biodiversity Action Plan (UK BAP). The original lists of UK BAP priority species and habitats were created between 1995 and 1999, and were subsequently updated in 2007, this process has now been succeeded by the "UK Post-2010 Biodiversity Framework". More details are available on the JNCC website.
For species which have started breeding in the last 150 years, either naturally or through being introduced, the year and county of the first confirmed breeding record is noted, see Holloway (1996) for more details.
Historical Population Trend
Although formal population monitoring schemes for Britain's bird populations only commenced in earnest in the 1960s, our avifauna had well been well studied for at least the two preceding centuries. This knowledge accumulated in various county avifaunas providing a rich, but qualitative, picture of the patterns of change in bird numbers over an extended period of time. Building on earlier reviews (Alexander & Lack 1994; Parslow 1973; Sharrock 1974), Gibbons, Avery & Brown (1996) brought together this wide-ranging body of knowledge to produce a semi-quantitative measure of long-term poplation changes in a broadly comparable way across species. This comparison was, of necessity, rough and ready and resulted in a qualitative score for each species and time period ranging from -5 (huge decrease, widespread decline) through to +5 (huge/spectacular increase). Clearly, the amount of information available for each species varies, being best for those that are rare/scarce (perhaps because of of previous declines) or show strong changes especially in population distrbution; information about the commonest species, or those showing little aparent change tends to be scant.
We have condensed their scale into categories of widepread decline (moderate: orange (-2, -3), severe: red (-4, -5)) or increase (moderate: turquoise (+2, +3); substantial: olive (+4, +5)), or periods of little, or localised, change (grey, with arrows indicating a tendency to increase (+1) or decrease (-1); a tilde (~) signifies a trend that is either fluctuating, locally variable, or for which there is little actual information(0)) and adjusted a small number of categories where subsequent information suggested it was necessary. We have then added two more recent periods (broadly corresponding to the time of operation of CBC and BBS) using the same scoring system. It should be noted that even recently there are still some species, notably those that are cryptic, or hard to survey, for which we have poor knowledge of the overall magnitude of change.
Any interpretation of these should bear in mind the qualitative nature of the asessments (some of the more notable caveats are discussed by Gibbons et al. (1996)) and they should be treated accordingly - as "best guesses", especially when comparing acoss species or time periods.
Information on habitats occupied is derived from the BTO's Breeding Bird Survey (BBS). In this survey, habitat is recorded in each of ten transect sections in a 1-km square, according to the hierarchical classification of Crick (1992), outlined here. For these purposes, we generally only consider the top two levels of codes, and we have amalgamated some categories (see below). We consider birds using terrestrial and aquatic habitats separately and used data from 2000 - 2003.
For each year, the proportion of all transect sections of each habitat type occupied by a species was calculated. Proportional occurrence in each habitat was then scaled (divided) by the occurrence in the most frequent habitat, so habitat occurrence ranges from 0 (absent) to 1 (in the most frequently occupied habitat) for all species, irrespective of how abundant they are. These scaled values were then averaged across the three years considered (2000, 2002, 2003; no data were available for 2001) and assigned to three categories.
Most frequent habitats: scaled proportional occupancy >= 0.95
Also common in habitats: scaled proportional occupancy >= 0.7
And found in: scaled proportional occupancy >= 0.5
Thus, for each of the habitats listed a bird is at least half as likely to occur there as it is in the habitat in which it is commonest.
Habitat Description (using BTO habitat codes)
Towns F1, F2 (includes urban and suburban areas)
Villages; F3 (areas of more scattered dwellings)
Deciduous Wood A1, A4 (woodland is more than 5m tall)
Coniferous Wood A2, A5 (woodland is more than 5m tall)
Scrub B1-B7 (shrubs or young trees <5m tall)
Arable Farmland E4
Pasture Farmland E1, E2 (improved or unimproved, enclosed)
Moorland C2, C3 (usually unenclosed, upland grazing)
Bog D4, D6, D7 (waterlogged peat, with Sphagnum Grass)
Heath C1, C4, C5, D1, D5 (dry semi-natural grass, low-lying)
Marsh C6, C8, D2
Coastal Habitat C9, H1-H5
Estuaries C9, H3, H4 (incl. saltmarsh & brackish lagoons)
Open Shore H1, H2, H5
Along Streams G6, G8 (rivers and ditches <2m wide)
Along Rivers G7, G9, G10 (rivers and ditches >2m wide)
Lakes G3, G4 larger than 450m2 (~2 tennis courts)
Ponds G1, G2, G5 (smaller than 450m2 and gravel pits)
Mean Arrival Dates
For summer migrants mean arrival date in southern England (based on data from four observatories (Dungeness and Sandwich Bay, Kent, Portland Bill, Dorset and Bardsey, Gwynedd) is given. For more details of this study, click here. For a fuller picture of the time a species can be seen, consult the BirdTrack results page, a link is given below.
Breeding (Summer) population sizes are given for Europe, excluding Russia (for which population estimates are generally large and relatively poorly known). All estimates are for the year 2000 (or the closest available year) and are taken from Burfield & van Bommel (2004). Population estimates for many countries are not precise, so overall minimum and maximum figures are quoted. Where the UK breeding population is measurable proportion of the European total this is noted to give general guidance on the importance of the UK breeding population in a European context. It is calculated simply as the UK estimate (or midpoint if estimate is a range) divided by the midpoint of the European population estimate range, so should only be used as a rough indication.
For 48 terrestrial (farmland and woodland) species that are widespread across Europe, Pan-European indices of population trend have been created by combining monitored population trends from 18 countries as part of a project by BirdLife International and the European Bird Census Council. Links to the relevant species are provided.
This link to the BirdLife International website provides summary details of the of the European population size and trend presented in Burfield & van Bommel (2004). A map showing the geographical pattern of population change and a table detailing population size and trend (together with some indication of data quality) for each country are presented. See Burfield & van Bommel (2004) for a full description and methods of the results presented. A summary for countries in the European Union is available here (note this is a 1.3 MB pdf file).
Details of UK and EU legislation under which the species is specifically protected. In the UK most species receive general protection under the Wildlife & Countryside Act (1981), the EU Wild Birds Directive (EC/79/409)and the Bern Convention on Conservation of Wildlife & Habitats ('Habitats' Directive). The Bonn Convention provides protection for migratory species in general, and waterbirds in particular under the African-Eurasian Waterbird Agreement. In each case the Schedule the species is listed on is given, asterisks indicate that listing is restricted in some way, either to a particular populations or race, or to a particular part of the schedule. If a UK Biodiversity Action Plan (BAP) has been drawn up, this is noted (together with Contact Organisation and Lead Partners, as at January 2006).
Wildlife & Countryside Act
The WCA aims to protect wildlife by prohibiting the killing or taking of animals. The Schedules under which birds are specificaly listed are:
Schedule 1: Birds which are protected by special penalties.
Schedule 2: Birds which may be killed or taken.
Schedule 3: Birds which may be sold.
Schedule 4: Birds which must be registered and ringed if kept in captivity
Schedule 9: Non-native species not to be released into the wild
Wild Birds Directive
The WBD aims to protect wild birds and their habitats throughout Europe, in part through the designation of Special Protection Areas (SPA). Amendments up to September 2003 are included.
Annex I: The directive requires these species to be the subject of special conservation measures concerning their habitat in order to ensure their survival and reproduction
Annex II: These species may be hunted, though hunting of some species is limited to particular countries
Annex III: For these species 'trade activities' shall not be prohibited; trade in all other species is prohibited.
The Convention on the Conservation of European Wildlife and Natural Habitats aims to maintain populations of wild fauna and flora with a particular emphasis on endangered species. Amendments up to March 2002 are included.
Appendix II: Lists strictly protected species.
Appendix III: Lists protected species.
The Convention on the Conservation of Migratory Species of Wild Animals aims to provide a framework for the conservation of migratory species and their habitats by means of protection and the conclusion of international agreements. Amendments up to December 2002 are included.
Appendix I: Lists species in danger of extinction throughout all or major parts of their range.
Appendix II: Lists species which would benefit from international cooperation in their conservation and management.
African-Eurasian Waterbird Agreement
AEWA is a daughter agreement to the Bonn Convention that aims to conserve migratory waterbirds through coodinated measures across the flyway. Those species to which the agreement applies are listed here. Amendments up to September 2002 are included.
Convention on International Trade in Endangered Species of Wild Fauna and Flora
CITES aims to ensure that international trade in wild animals and plants does not threaten their survival. Amendments up to October 2003 are included.
Appendix I: Species threatened with extinction, international trade is prohibited.
Appendix II: Species that may become threatened with extinction if trade is not closely controlled, the Appendix also includes some 'look-alike' species.
Natural Environment and Rural Communities (NERC) Act 2006
The Natural Environment and Rural Communities (NERC) Act came into force on 1st Oct 2006. Section 41 (S41) of the Act requires the Secretary of State to publish a list of habitats and species which are of principal importance for the conservation of biodiversity in England. The S41 list is used to guide decision-makers such as public bodies, including local and regional authorities, in implementing their duty under section 40 of the Natural Environment and Rural Communities Act 2006, to have regard to the conservation of biodiversity in England, when carrying out their normal functions.
Section 41: These are the species found in England which were identified as requiring action under the UK BAP and which continue to be regarded as conservation priorities under the UK Post-2010 Biodiversity Framework.
Occurrence of Rarities
Date of First Occurrence
For species recorded since the 1950s details of the first sighting have usually been published British Birds. The first such record is validated by the BOU Records Committee (BOURC) before being added to the British list (which since 1997 has been distinct from the Irish list). All subsequent records are verified (as far as is possible) by the British Birds Rarities Committee (BBRC), which was consituted in its present form in 1958. Where possible we give the county and year of first sighting, together with the original publication (or a subsequent paper if this substantially revises the original record, for example Moustached Warbler). Birds first recorded since 1600 (mostly scarce migrants and accidentals) are taken primarily from Palmer (2000). where a substantive article documents the first occurrence reference will be made to this in preference; details of many of the accounts are collated in Sharrock (1983) and Pitches & Cleeves (2005). For more common species, their first listing in some of the major earlier works (starting with Turner's work of 1544) is noted, taken from Bircham (2007).
Number of Records
For species still considered by the BBRC, the total number of accepted records is given. This is taken from the most recent published report in British Birds (the year to which the report refers is noted, it will generaly have been published in the journal a couple of years subsequently). For species where the information is available links are given to the BBRC website where details of the number of records each year may be found. Where there are sufficient records, we have given an indication of the months in which most records occur, based largely on Dymond et al. (1989). Counties are grouped by country (Scotland and Wales) or region (England). We have attempted to give the year of the most recent occurrence for each county that had been accepted by BBRC up to the point of the report considered. In general, species that have been recorded more recently (particularly in multiple counties) are likely to occur more frequently than those last recorded some time previously. A photograph or good description will be required if a record of these species is to be accepted, see the BBRC website for details.
Alexander, W. B. & Lack, D. 1944. Changes in status among British breeding birds. British Birds 38: 42-45, 62-69, 82-88.
Baker, H., Stroud, D., Aebischer, N.J., Cranswick, P.A., Gregory, R.D, McSorley, C.A., Noble, D.G. & Rehfisch, M.M. 2006. Population estimates of birds in Great Britain and the United Kingdom. British Birds 99:25-44.
Bircham, P. 2007. A history of ornithology. Collins, London.
Burfield, I. & van Bommel, F. 2004. Birds in Europe: population estimates, trends and conservation status. Birdlife International, Cambridge.
Crick, H.Q.P. 1992. A bird-habitat coding system for use in Britain and Ireland incorporating aspects of land-management and human activity. Bird Study 39:1-12.
Dymond, J.N., Fraser, P.A. & Gantlett, S.J.M. (1989) Rare birds in Britain and Ireland. T&AD Poyser, Calton.
Eaton, M.A., Brown, A.F., Noble, D.G., Musgrove, A.J., Hearn, R.D., Aebischer, N.J., Gibbons, D.W., Evans, A. & Gregory, R.D. 2009. Birds of Conservation Concern 3: the population status of birds in the United Kingdom, Channel Islands and Isle of Man. British Birds 102:296-341.
Fraser, P.A. & Rogers, M.J. 2001. Report on scarce migrant birds in Britain in 1999. British Birds 94:560-589.
Gibbons, D.W., Reid, J.B. & Chapman, R.A. 1993. The New Atlas of Breeding Birds in Britain and Ireland: 1988-1991. Poyser, London.
Mead, C.J. 2000. State of the nation's birds. Whittet Books, Stowmarket, Suffolk.
Musgrove, A., Aebischer, N., Eaton, M., Hearn, S., Newson, S., Noble, D., Parsons, M., Risely, K. & Stroud, D. 2013. Population estimates of birds in Great Britian and the United Kingdom. British Birds 106:64-100.
Palmer, P. 2000. First for Britain and Ireland 1600-1999. Arlequin Press, Chelmsford, Essex.
Parslow, J. 1973. Breeding Birds of Britain and Ireland: a historical survey. Poyser, Berkhamsted.
Pitches, A. & Cleeves, T. 2000. Birds new to Britain and Ireland 1980-2004. Poyser, London.
Sharrock, J. T. R. 1974. The changing status of breeding birds in Britain and Ireland. In: Hawksworth, D. L. (ed.) The Changing Flora and Fauna of Britain, pp. 203-220. Academic Press, London.
Sharrock, J.T.R. 1983. Birds new to Britain and Ireland. Poyser, Calton, Berkshire.
Working together for seabirds
BTO work supports effective monitoring of our seabirds and aims to provide opportunities for a new generation of seabird surveyors.
Gull ID virtual training (2 sessions, Wednesdays 10am)
The training will consist of two weekly online modules of 90–100 minutes each, complemented by supported self-study exercises which will be provided after each session. The training will be run by BTO staff members Nick...