Number Occurring in Britain
This is an indication of the number of birds (or pairs for breeding populations) occurring in Britain each year.
For birds that breed or regularly winter in Britain, this information is a summarised version of information presented in the 'Population and Distribution' section, where more details are available.
For birds which occur on passage, annual mean counts in Britain for the period 1990-1999 have been taken from Fraser & Rogers (2001). These totals include only those records which have been reported and fully validated by the appropriate records committee.
For vagrants and accidental visitors, an annual mean number of records for the period 1958-2000 was calculated from the total number of birds reported in Rogers et al. (2001). Again, these totals only include those records which have been reported and fully validated by the appropriate records committee.
The conservation status of the species is given at three levels, National (UK), European and Global.
The conservation status of 246 regularly occurring birds in the U.K. has been reviewed by the leading governmental and non-governmental conservation organisations (Eaton et al. 2009). This resulted in each species being placed on one of three lists: Red, Amber or Green.
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. Read more on the details of the criteria and how they were applied. Fify-two species have been placed on the Red List and 126 on the Amber List. The remaining 68 species are Green listed.
The conservation status of birds in Europe has been assessed twice (Tucker & Heath 1994, Burfield & van Bommel 2004). The more recent excercise classified 524 species into four categories, based on applying international 'Red List' criteria at a regional (continental) level, details of which are summarised below. The first three categories represent Species of European Conservation Concern (SPEC).
SPEC 1 species are those which are of global conservation convern.
SPEC 2 species are those which have an unfavourable conservation status in Europe (if the population is threatened, declining, depleted from historical levels or is found only in a few locations) and is concentrated in Europe (i.e more than 50% of the global population occurs in Europe).
SPEC 3 species are which have an unfavourable conservation status in Europe (see above), but which are not concentrated in Europe.
Species which do not fulfil these criteria are regarded as non-SPEC species and of least conservation concern.
In the U.K. there are 3 SPEC 1 species, 24 SPEC 2 species and 43 SPEC 3 species, i.e. 70 species are of European conservation concern. A further 140 were assessed as of least concern (though of these 58 have populations concentrated in Europe).
Species of global conservation concern are assessed by the International Union for Conservation of Nature and Natural Resources (IUCN) to "identify and document those species most in need of conservation attention if global extinction rates are to be reduced". Species of concern are placed on a global Red List, according to internationally accepted criteria (IUCN 2001). The primary categories, with an indication of the qualifying criteria, are:
Critically Endangered: A rapid population decline in the last 10 years, an extremely restricted range or very low population size and so faces an extremely high risk of extinction in the wild.
Endangered: Population decline of >50%, a restricted range or low population size and so faces a very high risk of extinction in the wild.
Vulnerable: Population decline of >30%, a limited range or small population size, so the population faces a high risk of extinction in the wild.
Near Threatened: A species which does not qualify for either of the three categories above, but which is close to doing so, or is likely to do so in the near future.
Species which do not fulfil these criteria are considered of Least Concern, though some for which information is relatively limited are highlighted as Data Deficient. An additional category of Extinct is reserved for those for which there is no reasonable doubt that the last individual has died. See the IUCN Criteria for a full explanation of the qualifying criteria for each category.
Summary Body Measurements
These measurements are intended to give a broad idea of the size of a particular bird in terms of approximate length (from beak tip to tail tip), wingspan (wingtip to wingtip in flight) and weight. It must be borne in mind that although a single figure (only) is given, individuals may differ considerably in size (often by as much as 10% or 20%); there may also be consistent differences between the sexes. Weights are the most variable body size measurement and where there is a substantial difference between males (M) and females (F) we have noted this, but we have not noted the fact that weight may vary considerably between seasons (birds are often heavier in winter), between areas (generally birds are larger in the north), and even within days. Most data are taken from Birds of the Western Palearctic or Birds of North America. More detailed biometric measurements are given later. For comparison the sizes of a range of common birds are:
|Wren||10 cm||15 cm||10 g|
|Robin||14 cm||21 cm||18 g|
|Blackbird||24 cm||37 cm||100 g|
|Pigeon (City)||32 cm||67 cm||300 g|
|Crow||46 cm||99 cm||500 g|
|Duck (Mallard)||58 cm||90 cm||1 kg|
|Goose (Greylag)||82 cm||164 cm||3 kg|
|Golden Eagle||82 cm||212 cm||4 kg|
|Mute Swan||152 cm||223 cm||9 kg|
A brief summary of the distribution of each species around the world is given, taken from Sibley & Monroe (1990). This is, of necessity, highly condensed, so only a broad brush picture is given. The breeding and wintering ranges of migratory species are indicated separately. Where a wintering range is described as "south to" it may be taken that the two ranges overlap and some individuals may not migrate the full distance. Where only a single range is given, the species may be resident (sedentary) in that area, or a proportion of the population may migrate a relatively short distance within that range. Areas where a species has been introduced and become well established away from its native range are also indicated. The use of abbreviations has been limited to n, s, e and w for northern, southern, eastern and western, or combinations of these.
A brief indication of the main habitats that a species is likely to be found in (primarily during the breeding season), taken from Sibley & Monroe (1990). These are not exhaustive and inviduals may be be found outside these, particularly on migration. Where a species regularly occurs in different habitats on migration or in the non-breeding season this is indicated. For a more detailed summary of the habitats British species are found in (in the breeding season) see the Population and Distribution section further down the page.
A brief summary of the major food-types eaten by each species. For most species diet varies according to the relative availability of prey items, both in different locations and through the year. In particular, young are often fed a different diet as they need protein and energy-rich food sources for growth. Information taken mainly from Snow & Perrins (1998) and Birds of North America.
Where 'insects' are referred to, this means the Class Insecta, e.g. beetles, flies, moths/butterflies, but not spiders (which have eight legs, not six, amongst other differences). For many species, the larval forms (e.g. caterpillars, grubs, leatherjackets) are eaten, and are particularly fed to nestlings, as they do not have the same hard, and indigestible, casing of the adult insect. 'Arthropods' include all the joint-legged invertebrates, i.e. insects, spiders, millipedes/centipedes and crustaceans (e.g. shrimps, crabs, woodlice). 'Invertebrates' includes arthropods and other groups, particularly molluscs (e.g. slugs, snails, or in marine environments, cockles, mussels etc.), earthworms and marine worms. For marine organisms, the planktonic, larval stages may be eaten particularly; these are small organisms which drift with the currents near the surface of the sea and most marine invertebrates go through several planktonic larval stages as they develop, before reaching adult size and shape. Vetebrates include mammals, birds, reptiles, amphibians and fish of an appropriate size.
A small fact regarding the species concerned. It may relate to some particularly interesting aspect of the bird's biology, or how it relates to man, either directly or through culture and history.
Burfield, I. & van Bommel, F. 2004. Birds in Europe: population estimates, trends and conservation status. Birdlife International, Cambridge.
Fraser, P.A. & Rogers, M.J. (2001) Report on scarce migrant birds in Britain in 1999. British Birds 94:560-589.
Eaton, M.A. et al. 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.
IUCN (2001) Red List categories and criteria, version 3.1. IUCN, Gland, Switzerland.
Rogers, M.J. & the Rarities Committee (2001) Report on rare birds in Great Britain in 2000. British Birds 94:452-504.
Sibley, C.G. & Monroe, B.L. (1990) Distribution and taxonomy of birds of the world. Yale University Press.
Snow, D.W. & Perrins, C.M. (1998) The birds of the western Palearctic, Concise editon. Oxford University Press.
Tucker, G. & Heath, M. (1994) Birds in Europe: their conservation status. Birdlife International, Cambridge.