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C5. Birds of the wider countryside and at sea

a. Farmland birds

b. Woodland birds

c. Wetland birds

d. Seabirds

e. Wintering waterbirds

Type: State Indicator

Introduction 

The indicator shows relative changes in the abundance of common native birds of farmland and woodland and of freshwater and marine habitats in the UK. Bird populations have long been considered to provide a good indication of the broad state of wildlife in the UK. This is because they occupy a wide range of habitats and respond to environmental pressures that also operate on other groups of wildlife. In addition, there are considerable long-term data on trends in bird populations, allowing for comparison between short-term and long-term changes. Because they are a well-studied taxonomic group, drivers of change for birds are better understood than for some other species groups, which enables interpretation of observed changes.

Key results

 Tractor icon In 2019 the UK farmland bird index was 45% of its 1970 value. Short term, between 2013 and 2018, the smoothed index decreased significantly by 5%.

Tree icon In 2019 the UK woodland bird index was 25% below its 1970 value. Short term, between 2013 and 2018, the smoothed index decreased significantly by 7%. 

Waterdrop icon In 2019 the water and wetland bird index was 14% lower than in 1975. However, more recently the smoothed index increased very slightly and non-significantly, by 1% between 2013 and 2018. 

water icon In 2019, the breeding seabird index in the UK was 24% lower than in 1986, slightly above the lowest level recorded (of 31% lower than 1986, recorded in 2013). Short term, between 2013 and 2018, the unsmoothed breeding seabird index increased, non-significantly, by 3%.

flake icon In 2018 to 2019, the wintering waterbird index was 88% higher than in 1975 to 1976. Short term, between 2012 to 2013 and 2017 to 2018, the smoothed index decreased by 3%. 

Figure C5ai. Breeding farmland birds in the UK, 1970 to 2019.

Left part is a line graph showing changes to the index for breeding farmland birds between 1970 and 2019. The index declined sharply between the late 1970s and the early 1980s and has continued to decline at a slower rate since then. Right part includes two 100% stacked bar charts showing long- (since 1970) and short-term (latest 5 years) trends within the breeding farmland birds index in terms of increase (strongly or weakly), decrease (strongly or weakly) or showing little change.

Notes:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence interval shaded.
  2. The figure in brackets shows the number of species in the index.
  3. The bar chart shows the percentage of species within the indicator that have increased, decreased, or shown little change, based on set thresholds of annual change.

Source: British Trust for Ornithology; Defra; Joint Nature Conservation Committee; Royal Society for the Protection of Birds.

Figure C5bi. Breeding woodland birds in the UK, 1970 to 2019.

Left part is a line graph showing changes to the index of breeding woodland birds between 1970 and 2019. Decline occurred between the early 1980s and early 1990s.  Since 1995, the index has been more stable. Right part is two 100% stacked bar charts showing percentage of species within the index that have increased (strongly or weakly), decreased (strongly or weakly) or shown little change over both the long term (since 1970) and short term (latest 5 years).

Notes:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence interval shaded.
  2. The figure in brackets shows the number of species in the index.
  3. The bar chart shows the percentage of species within the indicator that have increased, decreased, or shown little change, based on set thresholds of annual change.

Source: British Trust for Ornithology; Defra; Joint Nature Conservation Committee; Royal Society for the Protection of Birds.

Figure C5ci. Breeding water and wetland birds in the UK, 1975 to 2019.

Left part is a line graph showing changes to the index of breeding water and wetland birds between 1975 and 2019. The trend has remained fairly stable for most of this period. Right part is two 100% stacked bar charts showing the percentage of individual species within the UK breeding water and wetland birds index that have increased (strongly or weakly), decreased (strongly or weakly) or shown little change over both the long term (since 1975) and short term (latest 5 years).

Notes:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line) and its 95% confidence interval shaded.
  2. The figure in brackets shows the number of species in the index.
  3. The bar chart shows the percentage of species within the indicator that have increased, decreased, or shown little change, based on set thresholds of annual change.

Source: British Trust for Ornithology; Defra; Environment Agency; Joint Nature Conservation Committee; Royal Society for the Protection of Birds.

Figure C5di. Breeding seabirds in the UK, 1986 to 2019.

Left part is a line graph showing how the unsmoothed trend for the breeding seabird index has changed between 1986 and 2019. Right part is two 100% stacked bar charts showing the percentage of individual species within the UK breeding seabird index that have increased (strongly or weakly), decreased (strongly or weakly) or shown little change over both the long term (since 1986) and short term (latest 5 years).

Notes:

  1. The line graph shows the unsmoothed trend (dashed line) with its 95% confidence interval (shaded area) – no smoothed trend is available for seabirds, but this will be available in future publications.
  2. The figure in brackets shows the number of species in the index.
  3. The bar chart shows the percentage of species within the indicator that have increased, decreased, or shown little change, based on set thresholds of annual change.
  4. The breeding seabird index has now been updated with data up to and including 2019. This follows a brief hiatus in updates since 2016 when the Seabird Monitoring Programme Steering Group made the decision to put the analysis and publication of the annual SMP report on hold enabling staff time to be dedicated to the breeding seabird census, Seabirds Count.

Source: British Trust for Ornithology; Defra; Royal Society for the Protection of Birds; Seabird Monitoring Programme (co-ordinated by Joint Nature Conservation Committee).

Figure C5ei. Wintering waterbirds in the UK, 1975/76 to 2018/19.

Right part is a line graph showing changes to the wintering waterbirds index between 1975 to 1976 and 2018 to 2019. The graph also shows trends for the wildfowl index and waders index over the same time period. All 3 indices peaked in the late 1990s and have since declined. Right part is two 100% stacked bar charts showing long- and short-term percentage changes trends of wintering waterbird in terms of having increased (strongly or weakly), decreased (strongly or weakly) or shown little change.

Notes:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line).
  2. The figure in brackets shows the number of species in the index.
  3. The bar chart shows the percentage of species within the indicator that have increased, decreased, or shown little change, based on set thresholds of annual change.
  4. Based on surveys during winters – so 1975/76 refers to the period from September 1975 to March 1976.
  5. Data from wintering waterbirds monitoring schemes are based largely on full counts at colonies or at wetland and coastal sites of markedly varying size. This means that bootstrapping methods cannot be applied reliably and hence trends for these groups are currently presented without confidence intervals.

Source: British Trust for Ornithology; Defra; Joint Nature Conservation Committee; Royal Society for the Protection of Birds; Wildfowl and Wetlands Trust.

Assessment of change in bird populations

  Long term Short term Latest year
Farmland birds

Deteriorating
1970–2018

Deteriorating
2013–2018

No change (2019)
Woodland birds

Deteriorating
1970–2018

Deteriorating
2013–2018

Increased (2019)
Wetland birds

Deteriorating
1975–2018

Little or no overall change
2013–2018

Increased (2019)
Seabirds Not assessed Not assessed Not assessed
Wintering waterbirds

Improving
1975/76–2017/18

Little or no overall change
2012/13–2017/18

Increased (2018/19)

Notes:

  1. Whilst latest year percentage changes in these indices are reported based on the most recent unsmoothed data point (2019), the formal long-term and short-term assessments of the statistical significance of these changes are made using the smoothed data to 2018. This is because the most recent smoothed data point (2019) is likely to change in next year’s update when additional data are included for 2020.
  2. Analysis of the underlying trends is undertaken by the data providers. Smoothed data are available for farmland, woodland, wetland and wintering waterbirds, but not for seabirds.
  3. The traffic light assessment for the seabirds measure has been removed until a way of assessing variability is devised. This follows recommendations in a quality assurance science panel report, dated January 2016.

Tractor icon The long-term decline of the farmland bird indicator in the UK has been driven mainly by the decline of those species that are restricted to, or highly dependent on, farmland habitats (the ‘specialists’, which account for 12 of the 19 species in the indicator). Between 1970 and 2019, the unsmoothed index for farmland specialists declined by 70% while for farmland generalists it declined by 13%. Of the 12 farmland specialists, five (corn bunting, grey partridge, starling, turtle dove, and tree sparrow) have undergone declines in excess of 80% since 1970 due largely to changes in farmland practices. Two farmland specialists (stock dove and goldfinch) have more than doubled over the same period, illustrating how responses to pressures varies among species. Generalist species have fared better than specialists although the rates of decline have been more alike during the last decade. Amongst the generalists, woodpigeon and jackdaw populations have more than doubled relative to 1970 levels, whereas the yellow wagtail has declined by 68%, greenfinch by 64% and kestrel by 48%. Overall, farmland birds have been impacted by changes in the suitability of farmland for breeding and wintering as well as pressures faced by those that undertake long migrations. However, most farmers can and do take positive steps to conserve birds on their land. In particular, a number of incentive schemes encourage improved environmental stewardship in farming, with some measures specifically designed to help stabilise and recover farmland bird populations. These include the provision of over-wintered stubbles and planted wild bird crop covers to provide seed in the winter, uncropped margins on arable fields and sympathetic management of hedgerows. There is growing evidence that such action can deliver local recoveries in farmland bird populations and thus, if delivered at appropriate scale, wider recovery. The decline in greenfinch is considered to be caused by the disease trichomonosis.

Tree icon The woodland bird index contains data for 37 species. The relatively flat trend for all woodland birds since the mid-1990s masks different underlying trends for specialist species, those which are highly dependent on woodland habitats, and generalist species, which are found in a wide range of habitats, including woodland. In 2019, the woodland specialists index was 45% lower than in 1970, while the index for woodland generalists was 11% higher than in 1970. Indices for four generalist woodland species (bullfinch, song thrush, dunnock and tawny owl) have declined more than 30% since 1970; and song thrush by 49%. Over the same period, populations of long-tailed tit and great tit increased by 102% and 79% respectively. Five woodland specialists, lesser spotted woodpecker, lesser redpoll, spotted flycatcher, capercaillie and willow tit, have declined by over 80% relative to 1970 levels, with the latter down by 94%. In contrast, populations of blackcap have more than doubled over the same period and nuthatch and great spotted woodpecker have more than trebled in numbers. Trends in long-distance migrants may possibly reflect changing conditions on their wintering grounds whereas declines in residents such as lesser spotted woodpecker, willow tit and capercaillie must be due to factors on their breeding grounds. Probable causes for this include a lack of woodland management (including the cessation of traditional practices such as coppicing) and increased deer browsing pressure, both of which result in a reduced diversity of woodland structure and reduced availability of suitable nesting and foraging habitats. 

Waterdrop icon The breeding water and wetland bird measure can be disaggregated to four sub-habitat indicators (birds of fast flowing water, birds of slow and standing water, birds of reedbeds and birds of wet grasslands) although each is composed of relatively few species. Birds of slow flowing and standing water, including mallard and tufted duck, have shown the most positive trend. In 2019 the index for this group was 33% higher than in 1975 although there has been a significant 7% decrease in the short-term period between 2013 and 2018. The index of birds of wet grassland, including a number of wader species, has decreased by 52% since 1975, and the index for birds of fast flowing water (including dipper) decreased by 29% compared to 1975. 

Water icon The seabird measure is focussed on the marine environment. Accordingly, for a number of species (e.g. herring gull, great cormorant), the indicator uses data for coastal populations (colonies within 5 km of the coastline) only, rather than data from all breeding areas of these species. This focusses the indicator on changes at the coast and in marine waters but means changes in inland populations are not taken into account. In 2019, the breeding seabird index in the UK was 24% lower than in 1986, slightly above the lowest level ever recorded (of 31% lower than 1986, recorded in 2013). Despite fluctuations, the indicator was largely flat from 1986 until the early-2000s when seabird numbers started to decline and the long-term trend (to 2018) shows a significant 28% decrease. However, more recently the unsmoothed breeding seabird index has increased, non-significantly, by 3% between 2013 and 2018. One of the 13 seabird species has increased since the beginning of the index in 1986; razorbill numbers have more than doubled. Two species have declined strongly since 1986; Arctic skua by 80% and black-legged kittiwake by 64%. The decline of black-legged kittiwakes has been linked to climate change impacts on marine food webs, and fishery pressures. However, there has been some improvement in the short term, during which black-legged kittiwakes have shown a strong increase, of 20% between 2013 and 2018. In addition to black-legged kittiwakes another two of the 13 seabird species have increased strongly between 2013 and 2018; razorbill and sandwich tern by 35% and 26% respectively. Numbers of great black-backed gull are decreasing strongly by 32% in the short term, although the long-term trend is a weak decline. Some seabirds have been impacted through predation by invasive non-native mammals such as rats and mink, though successful eradication programmes have been implemented in a number of areas and populations of some species have undergone local recoveries as a result.

Flake icon The wintering waterbird measure increased steadily from the 1975 to 1976 baseline to a peak in the late 1990s and has declined since. The indicator in 2018 to 2019 stands 88% above its 1975 to 1976 baseline. The separate wader and wildfowl indices show broadly similar patterns of increase followed by decrease, although the change in the wildfowl indicator has been greater. Amongst wildfowl, five of the 27 species showed a weak decline, with the indices for the European white-fronted goose, pochard, Bewick’s swan, and scaup halving since 1975 to 1976. Numbers of eider have declined by 35%. Gadwall and British/Irish greylag goose have increased by 15 and 13-fold respectively in the long term. Since 1975 to 1976, both the Svalbard Light-bellied Brent goose and whooper swan have increased nine-fold. Svalbard barnacle goose increased seven-fold and pink footed-goose by six-fold in the long term. Amongst waders, 40% of the species have increased, 53% showed little change and 7% have declined since the winter of 1975 to 1976. The indices for two waders (avocet and black-tailed godwit) have increased over eight-fold (avocet is only included in the indicator since 1989 to 1990). The indices for dunlin and ringed plover showed the steepest declines, declining by 49% and 36% respectively, since the winter of 1975 to 1976.

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Indicator description

The indices for farmland, woodland and breeding wetland birds show the year-to-year fluctuation in relative abundance, reflecting the observed changes in the survey results, and smoothed trends, which are used with their confidence intervals to formally assess the statistical significance of change over time. Smoothed trends reduce short-term peaks and troughs resulting from, for example, year-to-year weather and sampling variations.

Data from surveys of wintering waterbirds are based on full counts on wetland and coastal sites of markedly varying size. This means the standard bootstrapping methods used to estimate confidence intervals for the farmland, woodland and wetland indices, which are based on standardised sample-based surveys, cannot be applied. Assessments of change for the waterbird index are therefore made using a ‘5% rule’. If the index has increased or decreased by greater than or equal to 5%, the index is given a green or a red traffic light respectively. The traffic light assessment for the seabirds measure has been removed until a way of assessing variability is devised. This follows recommendations in a quality assurance science panel report, dated January 2016.

Composite indicators can mask a lot of variation among the species within them. The bar chart provided alongside the headline chart shows the percentage of species within that indicator that have increased, decreased or shown little change. Whether an individual bird species is defined as increasing or decreasing has been decided by its rate of annual change over the time period (long or short) of interest. If the rate of annual change would lead to a population decrease of 50% (halving), or a population increase of 100% (doubling) or more over 25 years, the species is said to have shown a ‘strong decline’ or a ‘strong increase’ respectively. Rates of change less than these but above +33% (increase) or below -25% (decrease) are labelled 'weak'. Asymmetric thresholds are used for declines and increases to represent symmetrical proportional change in an index. These thresholds for decline are based on the rates used in the Birds of Conservation Concern status assessment for birds in the UK. Note that for most species, particularly over the longer period, the change is statistically significant.

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Relevance

Bird populations have long been considered to provide a good indication of the broad state of wildlife. Birds occupy a wide range of habitats and there are considerable long-term data on changes in bird populations, which help in the interpretation of shorter-term fluctuations in numbers. As they are a well-studied taxonomic group, drivers of change for birds are better understood than for other species groups, which allows for better interpretation of any observed changes. Birds also have huge cultural importance and are highly valued as a part of the UK’s natural environment by the general public.

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Background

The indicator has been compiled in conjunction with the British Trust for Ornithology (BTO), the Joint Nature Conservation Committee (JNCC), the Royal Society for the Protection of Birds (RSPB), and the Wildfowl and Wetlands Trust (WWT). Data are obtained from a wide range of sources, principally:

Within the measures, each species is given equal weighting, and the annual index is the geometric mean of the individual species indices for that year. Populations of individual species within each measure may be increasing or decreasing irrespective of the overall trends. The individual species indices are largely derived by the modelling of sampled survey data, and estimates are revised when new data or improved methodologies are developed and applied retrospectively to earlier years. Further details about species and methods can be found on the British Trust for Ornithology website and by downloading the technical background document.

A table listing the species that are included in each index can be found in the datasheet. For each species, an estimate of change in the long term and in the short term is given, as well as an assessment of whether the species trend is increasing or decreasing.

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Goals and Targets

Aichi Targets for which this is a primary indicator

Strategic Goal B. Reduce the direct pressures on biodiversity and promote sustainable use.

Aichi Target 7 icon

Target 7: By 2020, areas under agriculture, aquaculture and forestry are managed sustainably, ensuring conservation of biodiversity.

Strategic Goal C. To improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity.

Aichi Target 12 icon

Target 12: By 2020, the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained.

Aichi Targets for which this is a relevant indicator

Strategic Goal B. Reduce the direct pressures on biodiversity and promote sustainable use.

Aichi Target 5 icon

Target 5: By 2020, the rate of loss of all natural habitats, including forests, is at least halved and where feasible brought close to zero, and degradation and fragmentation is significantly reduced.

Strategic Goal C. To improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity.

Aichi Target 11 icon

Target 11: By 2020, at least 17 per cent of terrestrial and inland water, and 10 per cent of coastal and marine areas, especially areas of particular importance for biodiversity and ecosystem services, are conserved through effectively and equitably managed, ecologically representative and well connected systems of protected areas and other effective area-based conservation measures, and integrated into the wider landscape and seascapes.

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Reference Title 
Birds of Conservation Concern 4 Summary leaflet
British Trust for Ornithology The Breeding Birds Survey Report
British Trust for Ornithology Indicators of wild bird populations
British Trust for Ornithology Waterways Breeding Bird Survey
British Trust for Ornithology Wetland Bird Survey
Defra Populations of wild birds 1970–2019
Joint Nature Conservation Committee Seabird Monitoring Programme
Royal Society for the Protection of Birds State of UK’s Birds 2020
Wildfowl and Wetlands Trust Waterbird Monitoring

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Downloads

Download the Datasheet and Technical background document from JNCC's Resource Hub.

Download the Evidence Statements (2016) for C5a, C5b, C5c, C5d, and C5e. More information on the Evidence Statements, including the project report, is available on Defra's website.

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Last updated: October 2021

Latest data available:  

2019 (farmland birds, woodland birds, wetland birds, and seabirds);

2018 to 2019 (wintering waterbirds)

 

This content is available on request as a pdf in non-accessible format. If you wish for a copy please go to the enquiries page.

 

Categories:

UK Biodiversity Indicators 2021

Published: .

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