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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

This indicator was updated in 2023.

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 2022 the UK farmland bird index was 60% below its 1970 value. The decline has continued at a slower rate in the short-term; showing a decline of 8%.

Tree icon In 2022 the UK woodland bird index was 37% below its 1970 value. In the last 5 years the index has decreased by 15%. 

Waterdrop iconIn 2022 the water and wetland bird index was 13% lower than in 1975. In the last 5 years the index decreased by 3%. 

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 breeding seabird index increased by 3%.

flake icon In the winter of 2021/2022, the wintering waterbird index was 88% higher than in the winter of 1975/1976. The index peaked in 1996, and has largely declined since, falling by 9% between 2016/2017 and 2021/2022.

Figure C5aia. Breeding farmland birds in the UK, 1970 to 2022

ukbi-2023-c5aia-farmland.png

ukbi-2023-c5aib-farmland.png

Notes about Figures C5aia and Figure C5aib:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence interval shaded.
  2. 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 C5bia. Breeding woodland birds in the UK, 1970 to 2022

ukbi-2023-c5bia-woodland.png

ukbi-2023-c5bib-woodland.png

Notes about Figures C5bia and Figure C5bib:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence interval shaded.
  2. 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 C5cia. Breeding water and wetland birds in the UK, 1975 to 2022

ukbi-2023-c5cia-water-wetland.png

ukbi-2023-c5cib-water-wetland.png

Notes about Figures C5cia and Figure C5cib:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line) and its 95% confidence interval shaded.
  2. 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.
  3. In Figure C5cia the lower confidence intervals for 1994 and 1995 were un-estimable, this is due to the high uncertainty around the population trend for Snipe which is a scarce species. As a result the lower confidence intervals on the graph abridges the two data points for 1993 and 1996.

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

Figure C5dia. Breeding seabirds in the UK, 1986 to 2019

ukbi-2023-c5dia-seabirds.png

ukbi-2023-c5dib-seabirds.png

Notes about Figures C5dia and Figure C5dib:

  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 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.
  3. The breeding seabird index has not been updated since 2021, and only includes 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 C5eia. Wintering waterbirds in the UK, 1975/76 to 2021/22

ukbi-2023-c5eia-wintering-waterbirds.png

ukbi-2023-c5eib-wintering-waterbirds.png

Notes about Figure C5eia and Figure C5eib:

  1. The line graph shows the unsmoothed trend (dashed line) and smoothed trend (solid line).
  2. 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.
  3. Based on surveys during winters – so 1975/76 refers to the period from September 1975 to March 1976.
  4. 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

1970–2021

Deteriorating

2016–2021

Decreased 

(2022)

Woodland birds

Deteriorating

1970–2021

Deteriorating

2016–2021

Decreased

(2022)

Wetland birds

Deteriorating

1975–2021

Deteriorating

2016–2021

No change 

(2022)

Seabirds

Not assessed

Not assessed

Not assessed

Wintering waterbirds

Improving

1975/76–2020/21

Deteriorating

2015/16–2020/21

No available data

Notes for Assessment of Change table:

  1. Whilst latest year percentage changes in the indices are reported based on the most recent smoothed data point (2022), the formal long-term and short-term assessments of the statistical significance of these changes are made using the smoothed data to 2021. This is because the most recent smoothed data point (2022) is likely to change in next year’s update when additional data are included for 2023.
  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 change 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.
  4. Due to the impacts of COVID-19, there are no unsmoothed data available for wintering waterbirds in 2020/21, as such a latest year change assessment is unavailable.

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 2022, the index for farmland specialists declined by 72% while for farmland generalists it declined by 22%. Of the 12 farmland specialists, five (corn bunting, grey partridge, starling, turtle dove, and tree sparrow) have experienced severe 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 rate of decline for generalists has been similar to the specialists in the short term.  Amongst the generalists, woodpigeon and jackdaw populations have more than doubled relative to 1970 levels whereas three of the generalist species have declined over the long-term period: greenfinch by 69%, yellow wagtail by 66% and kestrel by 54%. Of the remaining two generalist species: rook numbers have not changed overall, and reed bunting has declined at a lower rate (-33% over the long-term). 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. Changes in numbers experienced by some species may, to a lesser extent, be further driven by other pressures. For example, there is evidence of an adverse impact from disease for some species, most notably greenfinch.

Tree icon The woodland bird index contains data for 37 species. The overall trend 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 2022, the woodland specialists index was 55% lower than in 1970, while the index for woodland generalists was 5% lower than in 1970. Populations of 2 woodland generalist species (bullfinch and song thrush) have declined by more than 45% since 1970. Only one species, long-tailed tit, has increased (by 90%) in this period. Four woodland specialists, lesser spotted woodpecker, spotted flycatcher, capercaillie and willow tit, have declined by over 90% relative to 1970 levels. In contrast, populations of nuthatch have more than trebled over the same period and both blackcap and great spotted woodpecker have more than quadrupled 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. The index for birds of reedbeds is made up of 4 species, and is showing the most positive trend of these groups. In 2022 it was 16% higher than in 1975. In the short term it increased by 8%. In birds of slow flowing and standing water, which includes mallard, the index was 12% higher than in 1975. However, there has been a 14% decrease in the short-term period between 2016 and 2021, reflecting a negative turn-around in the fortunes of this group in the last decade. The index of birds of wet grassland, including a number of wader species, has decreased by 51% since 1975, and the index for birds of fast flowing water (including dipper) decreased by 20% compared to 1975. 

Water icon The breeding seabird index has not been updated since the publication in 2020. Therefore the trends presented here precede the onset of avian flu in Britain’s seabirds and the devastating effects this has had on many species.

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 and peaked in 1996, and has largely declined since, falling by 9% between 2016/2017 and 2021/2022. 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. Overall, the wildfowl index has nearly doubled (97% increase) and the wader index has increased by 66% since 1975/1976. However, both peaked in the late 1990s and have declined subsequently; between 2016/2017 and 2021/2022, the index for wildfowl declined by 11% and the index for waders declined by 5%. Long-term decreases were observed for the Bewick’s swan, European white-fronted goose, scaup, and pochard which declined by 87%, 70%, 68% and 60% respectively. Four of the 13 wildfowl species showing the strongest increases are: the British/Irish greylag goose, gadwall, whooper swan and Svalbard light-bellied Brent goose. The British/Irish greylag goose and gadwall are estimated to be increasing in wintering numbers by 37-fold and 14-fold respectively. Wintering numbers of whooper swan and Svalbard light-bellied Brent goose are also estimated to have increased by more than 10-fold. Amongst waders, 33% of the wader species increased, 60% showed little change and 7% declined. The indices for avocet and black-tailed godwit showed the strongest increases, wintering numbers now more than 12 and 9 times what they used to be (and avocet is only included in the indicator since 1989/1990). Dunlin have shown the steepest decline, declining by 49% since the winter of 1975/1976, and wintering numbers of ringed plover are now 39% lower.

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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 assessed as improving or deteriorating respectively. The change 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 charts 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

The UK and England Biodiversity Indicators are currently being assessed alongside the Environment Improvement Plan Targets, and the new Kunming-Montreal Global Biodiversity Framework Targets, when this work has been completed the references to Biodiversity 2020 and the Aichi Global Biodiversity Framework Targets will be updated.

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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Downloads

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

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Last updated: 2023

Latest data available:  

2022 (farmland birds, woodland birds, wetland birds and seabirds);

2021 to 2022 (wintering waterbirds)

      2019 (Seabirds)

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 2023

Published: .

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