- Conservation listings: First, the European conservation category is given, according to current listings by BirdLife International in Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004). These update the original listings of Tucker & Heath (1994). For SPECs (Species of European Conservation Concern), the European Threat Status is also given. The current SPEC categories are as follows:
- SPEC 1
Species of global conservation concern, according to the latest assessments by BirdLife International and IUCN (www.birdlife.org/datazone/species/search)
- SPEC 2
Species with an unfavourable European conservation status, and with more than half of the global breeding or wintering population concentrated in Europe
- SPEC 3
Species with an unfavourable European conservation status, but with less than half of the global breeding or wintering population within Europe
Other species, not considered to be of European conservation concern, and assessed as 'secure', have no SPEC category but are placed into two further groupings:
- Species with a favourable European conservation status, and with less than half of the breeding or wintering population within Europe (Non-SPEC)
- Species with a favourable European conservation status, but with more than half of the global breeding or wintering population concentrated in Europe (Non-SPECE)
The UK conservation listing, given next, is taken from The Population Status of Birds in the UK (Eaton et al. 2009 (BoCC3); see PSoB pages). These assessments supersede two earlier Birds of Conservation Concern listings (Gibbons et al. 1996, Gregory et al. 2002). There are three categories, as follows:
- Red – high conservation concern
- Amber– medium conservation concern
- Green– all other species (except introduced species, which are not classified)
The main reason or reasons for listing as red or amber are also given. NB:
- SPEC 1 (globally threatened) species are automatically red listed, and SPEC 1(near threatened), SPEC 2 or SPEC 3 species are amber listed (unless they are introduced or a red-list criterion applies)
- Red or amber listing may stem from decline, localisation or international importance of non-breeding as well as breeding populations in the UK
- Rates of population decline used to assess red and amber listing were generally derived from CBC/BBS results for the 25-year period 1981–2006 or for 1969–2006, and do not take more recent changes into account
- Range declines were generally calculated from the numbers of 10-km squares occupied in the 1968–72 and 1988–91 national breeding atlases (Gibbons et al. 1993) but made use of more recent material where available
- Historical decline (in UK over the period 1800–1995) was assessed by literature review
For the first time, BoCC3 has classifird races, for polytypic species, where two or more races occur regularly in the UK. On occasion the listing for a race may differ from that for the species as a whole. These race-level assessments are given alongside those for species level in our species pages although, since our report is mainly about breeding birds in UK, we have omitted races that occur only as migrants or winter visitors.
Following the signing of the Convention on Biological Diversity at the 'Earth Summit' in Rio de Janeiro in 1992, the statutory conservation bodies in the UK compiled Biodiversity Action Plans (BAPs) for 26 rare or threatened bird species, of which 12 are covered by this report. A BAP review published in 2007 has concluded that 56 UK bird species now qualify for BAPs and has recommended that certain subspecies (e.g. Fair Isle and St Kilda Wrens) should now be included as BAP priorities. Our report covers 31 of those species.
For 'priority species', you will find an onward link to the relevant JNCC priority species page. A note appears in this section if the species is one for which the Rare Breeding Birds Panel currently requires all breeding records to be submitted.
- SPEC 1
- Long-term trend: This summarises the headline trend in population size since 1967 from CBC/BBS,1975 from WBS/WBBS data, or 1984 from CES data. If there are no data available from these schemes, any assessment of trends covers the period since about the mid 1960s, but may also take historical data into account. Increases and declines that are described as 'shallow', 'moderate' or 'rapid' are generally statistically significant. The following terms are used:
- Rapid decline: >50% population decline according to CBC/BBS, WBS/WBBS or CES
- Moderate decline: 25–50% population decline according to CBC/BBS, WBS/WBBS or CES
- Shallow decline: 10–25% population decline according to CBC/BBS, WBS/WBBS or CES
- Decline/Increase: information has been derived from sources other than CBC/BBS, WBS/WBBS or CES
- Probable/Possible increase/decline: information has been derived from sources other than CBC/BBS, WBS/WBBS or CES, and the information is uncertain – see the status summary for details
- Stable/Fluctuating, with no long-term trend: no overall change, or change <10%
- Uncertain: the information from two monitoring schemes conflicts, or the data are unrepresentative of the species' total UK population – see the status summary for details
- Unknown: no information on the UK population trend is available
- Shallow increase: 10–50% population increase according to CBC/BBS, WBS/WBBS or CES
- Moderate increase: 50–100% population increase according to CBC/BBS, WBS/WBBS or CES
- Rapid increase: >100% population increase according to CBC/BBS, WBS/WBBS or CES
- UK population size: Periodic reports on population sizes of birds in Britain and in the UK, for the breeding season and for winter, are agreed by the Avian Population Estimates Panel (APEP), on which BTO, GWCT, JNCC, RSPB and WWT are represented (Stone et al. 1997, Baker et al. 2006, Musgrove et al. 2013). UK population estimates from the Panel's third report (Musgrove et al. 2013) are given for each of our species, with a shortened reference (APEP13) and a summary of how each estimate was derived. In a handful of cases, new information potentially superseding APEP13 is also presented.
- Key facts table: For 43 species only, there follows a table giving a summary of key facts for migration, habitat and diet.
- Status summary: This section provides a brief summary of the trends detailed for the species. Unless there is a separate Causes of change section for the species (see 11, below), it also indicates why such changes might have occurred, if this is known, with reference to any published information.
- Population trend graphs: The first, headline graph shows the most representative long-term trend in abundance for the species, and is followed under the 'Population changes in detail' header by further graphs from other schemes, including BBS graphs for separate UK countries, as available. Generally for these graphs there are annual estimates (dots), with a smoothed trend line and its 85% confidence interval. The Methods section provides details about how the trend data are calculated for each scheme. Index values provide a relative measure of population size on an arithmetic scale relative to an arbitrary value of 100 in one of the years of the sequence. If an index value increases from 100 to 200, the population has doubled; if it declines from 100 to 50, it has halved. A narrow confidence interval indicates that the index series is estimated precisely, and a wider one that it is less precise, though the scale of the y-axis must be taken into account. The use of 85% confidence limits allows relatively straightforward comparison of points along the modelled line: non-overlap of the 85% confidence limits is equivalent to a statistically significant difference at approximately the 5% level (Anganuzzi 1993).
- Population trends table: This table provides details of summarised percentage changes in population size, over the maximum period from each source, and from the past 25 years, 10 years and 5 years, where these figures are available. Further columns indicate the years included, the average number of census plots included in the analysis for each year, the percentage change (an increase if presented with no sign) and the upper and lower 90% confidence limits of that change. Note that positive and negative percentage changes are not directly equivalent: for example, a decrease of 20% would require an increase of 25% to restore the population to its former level. Where the confidence interval does not include zero, population declines are regarded as statistically significant. The 'Alert' column indicates where a statistically significant population decline is estimated to be of greater than 50% (>50) or between 25% and 50% (>25) (see the Alerts section for further details). The 'Comment' column lists any caveats that must be considered when interpreting the estimates. The caveats include:
- Small sample: For CBC/BBS, WBS/WBBS and CES data, a mean sample size of less than 20 (but more than 10) census plots was available; for BBS data from individual countries, a mean sample of less than 40 (but more than 30) plots was available.
- Unrepresentative?: Some trends may be marked as possibly unrepresentative of the stated region, owing to the original CBC plots being self-selected by observers and thus potentially a biased sample. This judgment was made either because the species' average abundance in 10-km squares containing CBC plots was less than that in other occupied 10-km squares, as measured by 1988–91 Breeding Atlas timed counts or frequency indices (Gibbons et al. 1993) or, where these figures could not be calculated, on expert opinion.
- Population trends by habitat: This chart shows the species' BBS trends for the 16-year period 1995–2011 for each of 12 broad, mutually exclusive habitat types. The data presented vary by species according to their sample sizes. The vertical axis shows the estimated percentage change over the period, with its 95% confidence interval, in relation to the overall change, indicated by a dashed line. Under 'More on habitat trends', the data for each habitat trend are presented as a table and as a graph.The graphs allow the patterns of change to be compared between habitat categories over time. There is more information on these trends here on the BBS pages.
- Demography graphs: Graphs from Constant Effort Sites or Nest Record Scheme data illustrate trends in productivity and survival. NRS graphs show annual means, with error bars to denote ±1 standard error; and quadratic or linear regression lines with their 95% confidence interval. For CES data, the smoothed trends are plotted with their 85% confidence limits (see CES section for details). CES survival graphs show annual estimates, ±1 standard error, but trends for these data have not been assessed.
- Demography table: This provides details of changes in demographic variables since 1968 (or a more recent year, depending on the availability of data). It lists the period of years concerned, the mean annual sample, the type of trend ('curvilinear' is for a significant quadradic trend, 'linear' is for a significant linear trend, 'none' is where the linear trend is not significantly different from horizontal), the modelled values (from the appropriate regression) for the first and last years and their difference (provided only where the trend is significant), and any caveats that must be considered when interpreting the data. Changes are presented either in the units given or as percentages, and are increases unless a minus sign is shown. The caveat 'Small sample' is given when the mean number of nest record cards contributing annually was in the range 10–30, or when the mean annual number of CES plots recording the species was less than 20 (but more than 10).
- Causes of change: For a selection of species (currently 54), information on the causes of the demographic changes we have observed has been removed from the Status summary paragraph and expanded under this heading.
- Additional information: Links to atlas maps and tables from previous atlas surveys, and the relevant pages of BirdFacts, BirdTrack and Garden BirdWatch, as available from the BTO web site, are provided on the side bar of each species page.
The 120 species in this report can be accessed in any order, via alphabetic and taxonomic lists. The taxonomic sequence is that maintained by the British Ornithologists' Union and updated in in its current British List. The vernacular and scientific names we use are also drawn from that list. Given this report's limited geographical scope, we use British rather than the international English names. Depending on the availability of data, the following will be found beneath each species heading: