© crown copyright 2020 · 2020. 11. 25. · national monitoring schemes1 [footnote 1: see ‘main...
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© Crown copyright 2020
This information is licensed under the Open Government Licence v3.0. To view this
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National Statistics Designation Statement
The statistics in this release have been designated as National Statistics. This status
means that statistics meet the highest standards of trustworthiness, quality and public
value, and it is Defra’s responsibility to maintain compliance with these standards.
These statistics last underwent a full assessment against the Code of Practice for
Statistics in 2012. See Assessment Report 173 Statistics on Sustainability and the
Environment in England and the UK. Since that assessment by the Office for Statistics
Regulation, we have continued to comply with the Code of Practice for Statistics.
This document/publication is also available on our website at:
https://www.gov.uk/government/statistics/wild-bird-populations-in-england
The statistical datasets for the publication can be found here:
https://www.gov.uk/government/statistical-data-sets/env08-wild-bird-populations-in-
england
Responsible Statistician: Christine Holleran
Any enquiries/feedback regarding this document/publication or the statistical datasets
should be sent to us at:
or
Biodiversity Statistics Team
Department for Environment, Food and Rural Affairs
Foss House, Kings Pool
1-2 Peasholme Green
York
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PB14639
Acknowledgements:
All photographs are by Natural England and are sourced from their flickr account. Starting
from the top left the images are: a reed bunting (by Bob Silver); a bullfinch (by Bob Silver);
a cormorant (by Dave Harrison); a redshank (by Andrew Sloan); a goldeneye (by
Aidanos); and a sanderling (by Andrew Sloan).
Contents
England executive summary ................................................................................................ 7
Why monitor bird populations? ............................................................................................ 8
Understanding the bird population indices ........................................................................... 8
Assessing trends ................................................................................................................. 9
1. Native breeding wild bird populations in England .......................................................... 11
2. Breeding farmland bird populations in England ............................................................. 13
3. Breeding woodland bird populations in England ............................................................ 17
4. Breeding water and wetland bird populations in England .............................................. 21
5. Breeding seabird populations in England ....................................................................... 28
6. Wintering waterbird populations in England ................................................................... 31
Main notes: methodological detail, limitations of the indicators and further information ..... 34
Annex A: Trends in bird species, by habitat group, in England .......................................... 36
Annex B Frequently asked questions ................................................................................ 51
England executive summary The combined all-species index has changed relatively little compared with around 45 years
ago, however, this masks considerable flux, with some species increasing and some species
decreasing. Changes by habitat are summarised below; unsmoothed figures are used for
comparison with the latest year; and smoothed indices to the penultimate year are used to
assess change over long or short-term trends as they reduce short-term peaks and troughs.
Latest year: 2019…
• the unsmoothed all-species index in England was 6% lower than in 1970.
• the unsmoothed farmland bird index was 42% of its 1970 value.
• the unsmoothed woodland bird index was 27% below its 1970 value.
• the unsmoothed water and wetland bird index was 1% above its 1975 value.
• the unsmoothed seabird index was 11% above its 1986 valuea.
• the unsmoothed wintering waterbird index was 76% higher in 2017/18 than in
1975/76, the index peaked in the second half of the 1990s and has declined since.
Table showing long and short-term smoothed trends at a glance for England
Index Long-term trend,
1970 to 2018
Short-term trend,
2013 to 2018
All bird species -8% (not significant) -1% (not significant)
Farmland birds -59% (significant) -6% (significant)
Woodland birds -28% (significant) -6% (significant)
Water and wetland birds (index started 1975) 4% (not significant) 1% (not significant)
Seabirdsa (index started 1986) 9% (not significant) 4% (not significant)
Wintering waterbirdsb (index started 1975/76,
change to 2017/18)
81% -6%
a The seabirds indicator is an unsmoothed trend as no smoothed trend is available
b Data from surveys of wintering waterbirds are based largely on full counts at colonies or 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.
Why monitor bird populations?
Bird populations have long been considered to provide a good indication of the broad state
of wildlife in England. 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 trends in the short term and long term. Because they are a well-studied
taxonomic group, drivers of change for birds are better understood than for other species
groups, which enables better interpretation of any observed changes. Birds also have
huge cultural importance and are highly valued as a part of England’s natural environment
by the general public. However, the bird indicators presented in this publication are not
intended, in isolation, as indicators of the health of the natural environment more widely.
It is not practical to determine changes in the actual number of birds for each species in
England each year, but it is possible and more reliable to assess their status by calculating
relative change, based on counts on representative sample plots surveyed as part of
national monitoring schemes1 [Footnote 1: See ‘Main notes’ at the end for more details of the surveys
sources used].
Trends in bird populations are used by policy makers, government agencies and non-
governmental organisations as part of the evidence base with which to assess the effects
of any kind of environmental management, such as agricultural practices, on bird
populations. The trends are also used to assess the effectiveness of environmental
interventions intended to address declines, such as agri-environment schemes targeted at
farmland birds.
Understanding the bird population indices
Individual bird species population trends, based on carefully designed surveys undertaken
largely by expert volunteers, are calculated as a series of annual indices. These relate the
population in a given year to a ‘baseline’ – the first year that data are available – which is
given a value of 100. Thereafter, the index is expressing the population as a percentage of
this ‘baseline’.
This annual Defra National Statistics Release presents data trends up to 2019 in
populations of common birds (species with a population of at least 300 breeding pairs) that
are native to, and breed in, England, with trends overall as well as for 4 main habitat
groups (see Annex A for a list of birds in each group). The release also presents trends for
wintering waterbirds, some of which also breed in England.
1 See ‘Main notes’ at the end for more details of the surveys sources used.
The charts presented combine individual species indices2 into a single indicator to provide
an overall trend for each group mentioned above [Footnote 2: Using a geometric mean - an
average calculated by multiplying a set of index values and taking the nth root, where n is the number of
index values. More information can be found in Introduction to the Wild Birds Population Indicator]. The
indices are considered to give reliable medium to long-term trends, but strong reliance
should not be attached to short-term changes from year to year.
Assessing trends
Two trends are referred to in the text: the unsmoothed indices show year-to-year
fluctuation in populations, reflecting the observed changes in the survey results, and
smoothed trends3, which are used to formally assess the statistical significance of change
over time [Footnote 3: There are currently no smoothed trends available for seabirds]. Smoothed
trends4 are used for both long and short-term assessments as they reduce the short-term
peaks and troughs resulting from, for example, year-to-year weather and sampling
variations as well as good or bad breeding seasons [Footnote 4: See analytical methods on BTO
website (www.bto.org/birdtrends2011/methodology.htm) Fewster et al. 2000. Ecology 81: 1970 to 1984].
The most recent year of data in the smoothed indices, i.e. 2019 in this update, is likely to
change due to the smoothing process following the inclusion of 2020 data in next year’s
update. As a result, it is not appropriate to make assessments that include this last inter-
year interval. Where results from the smoothed indices are quoted, this is clearly indicated.
These trends are based on estimates from surveys. Smoothed trends are presented with
95% confidence intervals (CI), which are a measure of the precision of these survey
estimates: a 95% CI means users can be 95% confident that the true value of an indicator
in a given year falls within the confidence interval around it. The width of confidence
intervals varies between habitat indicators it is influenced by the number of species in each
indicator and the precision of the individual species trends that make up the indicator. For
the indicators derived from species trends that cannot be statistically evaluated by this
method (e.g wintering waterbirds and all-species) a threshold of 5% is used to evaluate the
significance of the change.
Throughout this release, assessment periods are referred to as:
• ‘Long-term’ – an assessment of change since the earliest date for which data are
available; this varies among indicators and among individual species.
• ‘Short-term’ – an assessment of change over the latest 5 years for which data are
available.
2 Using a geometric mean - an average calculated by multiplying a set of index values and taking the nth root,
where n is the number of index values. More information can be found in Introduction to the Wild Birds
Population Indicator. 3 There are currently no smoothed trends available for seabirds. 4 See analytical methods on BTO website (www.bto.org/birdtrends2011/methodology.htm) Fewster et al. 2000.
Ecology 81: 1970 to 1984.
Annex A shows long-term and short-term assessments for each individual bird species.
Alongside the overall index, the percentage of species within each indicator that have
increased or decreased in the long term and in the short term is also shown. This is based
on the average rate of annual change over both assessment periods, categorised by how
much the population would change if that annual change continued for 25 years. The bar
chart illustrates the percentage of species falling into each category:
Strong increase: population increase of 100% or more
Weak increase: more than 33% but less than 100% increase
Little change: between a 25% decrease and a 33% increase
Weak decline: less than 50% but greater than 25% decrease
Strong decline: population decrease of 50% or more.
These thresholds are asymmetrical to represent symmetrical proportional change in an
index, i.e. the opposite of a 50% decline is a doubling (a 100% increase), not a 50%
increase. These thresholds are derived from those used in the Birds of Conservation
Concern5 status assessment for birds in the UK [Footnote 5: See the BTO website
(https://www.bto.org/our-science/projects/birdtrack/bird-recording/birds-conservation-concern)].
The bird population indices have been compiled in conjunction with the Royal Society for
the Protection of Birds (RSPB), the British Trust for Ornithology (BTO), the Wildfowl and
Wetlands Trust (WWT) and the Joint Nature Conservation Committee (JNCC).
5 See the BTO website (https://www.bto.org/our-science/projects/birdtrack/bird-recording/birds-conservation-
concern)
1. Native breeding wild bird populations in England
In 2019, the all-species index in England, based on the aggregated population trends of
118 breeding species, was 6% below its 1970 value.
The indicator declined between the late 1970s and the late 1980s, driven mostly by
declines in woodland and farmland birds, the all-species index has since levelled off and
showed little change (-1% and not significant) in the short term between 2013 and 2018.
Figure 1: Breeding wild birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Within the index, 31% of the 118 species increased, 35% showed little change and 32%
declined between 1970 and 2018. It was not possible to calculate a long-term trend for 3
species because their data series start in 2005 or later.
Short term
Over the short-term period between 2013 and 2018, 30% of species increased, 34%
showed little change and 36% declined.
Species breakdown
The all-species index is comprised of 118 species of birds, all widespread species with
populations of at least 300 breeding pairs for which there are sufficient data to calculate a
trend. Species trends within this index vary widely, from those increasing several-fold (e.g.
buzzard, Cetti’s warbler, great spotted woodpecker and collared dove) to those having
declined to less than a tenth of their 1970 numbers (turtle dove, willow tit, grey partridge,
lesser redpoll, spotted flycatcher and tree sparrow). The main patterns and drivers of
change are best considered by looking at the indices of species grouped by habitat below
in Figure 1a and described in greater detail in the following chapters.
Figure 1a: Populations of wild birds in England by habitat, 1970 to 2019
2. Breeding farmland bird populations in England
Farmland refers to the large proportion of England which is devoted to agriculture and
consists of arable land and pastures. Farmland also provides semi-natural habitats such
as hedgerows and field margins that provide food and shelter to birds.
In 2019 the England farmland bird index was 42% of its 1970 value. The majority of this
decline occurred between the late 1970s and early 1980s and was largely due to the
negative impact of rapid changes in many farmland management practices during this
period. The decline has continued at a slower rate more recently; the smoothed index
decreased significantly by 6% between 2013 and 2018.
Figure 2: Breeding farmland birds in England, 1970 to 2019
Notes: i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Since 1970, 21% of species showed a weak increase, 21% showed little change and 58%
showed either a weak or strong decline.
Short term
Over the short-term period between 2013 and 2018, 16% of species increased, 53%
showed little change and 32% declined.
Factors affecting farmland bird populations
The large declines in the abundance of many farmland birds have a number of known and
potential causes. For a large part, declines have been caused by the changes in farming
practices that have taken place since the 1950s and 60s, such as the loss of mixed
farming, a move from spring to autumn sowing of arable crops, change in grassland
management (e.g. a switch from hay to silage production), increased pesticide and
fertiliser use, and the removal of non-cropped features such as hedgerows. The rate of
these changes, which resulted in the loss of suitable nesting and suitable feeding habitats,
and a reduction in available food, was greatest during the late 1970s and early 1980s, the
period during which many farmland bird populations declined most rapidly.
Some farming practices continue to have negative impacts on bird populations, but 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.
For more information about the evidence for this indicator, see the evidence statement
‘Annex 1.03 Evidence Statement for C5a Farmland Birds’.
Species breakdown
The farmland bird index is comprised of 19 species. The long-term decline of the farmland
indicator for England has been driven mainly by the decline of those species that are
restricted to, or highly dependent on, farmland habitats (the ‘specialists’). Between 1970
and 2019, the farmland specialists index declined by 73%; farmland generalists declined,
also by 6%. The smoothed trend shows a significant decline of 74% for specialists and a
(non-significant) 10% decline for generalists (figure 2a).
Figure 2a: Breeding farmland birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trends (dashed lines) and smoothed trends (solid lines).
Farmland specialists
Changes in farming practices, such as the loss of mixed farming systems, the move from
spring to autumn sowing of arable crops, and increased pesticide use, have been
demonstrated to have had adverse impacts on farmland birds such as skylark and grey
partridge. Five farmland specialists (turtle dove, tree sparrow, grey partridge, corn
bunting and starling) have declined by in excess of 80% relative to 1970 levels. By
contrast, 2 other farmland specialists (stock dove and goldfinch) have more than doubled
over the same period, illustrating how responses to pressures varies between species.
Figure 2b: Breeding specialist farmland birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Overall, 17% of the 12 specialist species in the farmland indicator increased, 8% showed
little change and 75% declined over this long-term period. The indices for turtle dove, tree
sparrow, grey partridge, corn bunting and starling all show strong declines of 98%, 96%,
93%, 89% and 88% respectively since 1970. Specialist farmland species which increased
were goldfinch, by 174%, and stock dove, by 112%, over this long-term period.
Short term
The smoothed index shows that between 2013 and 2018 specialist farmland species
declined significantly by 6% on average. Over this period 42% of the 12 specialist species
showed a declining trend. In particular, turtle dove, grey partridge and whitethroat showed
strong declines in the short term, with turtle dove decreasing even faster, by 42%.
Yellowhammer showed a weak decline over both the long and short term. Between 2013
and 2018, 17% of specialist species increased, with goldfinch and stock dove both
increasing by 19% and 21% respectively over this short-term period.
Farmland generalists
There are 7 generalist farmland species included in the indicator and they utilise a wider
range of habitats than the specialist farmland species. Since 1970 the generalist farmland
smoothed index has fallen, not significantly, by 10%.
Figure 2c: Breeding generalist farmland birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Since 1970, generalist farmland species have fared better than specialists over the long
term; 29% of the 7 generalist species in the indicator increased, 43% showed little change
and 29% declined. The indices for woodpigeon and jackdaw populations have more than
doubled relative to 1970 levels, while numbers of yellow wagtail and greenfinch have
declined by 65% and 62% respectively.
Short term
The smoothed index shows that between 2013 and 2018 generalist farmland species
declined significantly by 7% on average. Only one of the seven species declined over this
period; greenfinch showing a strong decline of 46% whereas its long-term trend is a weak
decline. Greenfinch numbers have been negatively impacted by the disease
trichomonosis, which may also have affected the turtle dove, a farmland specialist, in
recent years. Jackdaw is the only species to have increased, by 10%, over this period.
3. Breeding woodland bird populations in England
Woodland trees and the understorey provide nesting for birds as well as foraging
opportunities and cover from predators.
In 2019 the breeding woodland bird indicator for England was 27% lower than in 1970.
The greatest decline occurred between the early 1980s and the early 1990s, since 1996
the index has been relatively stable although more recently the smoothed index decreased
significantly by 6% between 2013 and 2018.
Figure 3: Breeding woodland birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Since 1970, 24% of woodland species increased in number, 44% showed little change and
32% declined, the majority of the latter show a strong decline.
Short term
Over the short-term period between 2013 and 2018, 24% of species increased, 35%
showed little change and 41% declined. Three species showed a strong decline in the long
term and a strong decline in the short term. These are lesser redpoll, tree pipit and spotted
flycatcher; decreasing by 31%, 21% and 18% respectively between 2013 and 2018.
Numbers of chaffinch and redstart showed a long-term trend of little change, but a strong
decline in the short term.
Factors affecting woodland birds
The declines in woodland birds have several known and potential causes, such as 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, therefore, reduced availability of suitable nesting and
foraging habitats. Changes in farmland management, such as the removal of hedgerows,
adversely impacted many of the species in the indicator which have substantial
populations outside of woodland e.g. in farmland and gardens. In addition, several
declining woodland birds are long-distance migrants, and a decline in the extent or quality
of habitats used outside of the UK in the non-breeding season may be one factor affecting
these species. Positive factors include the increasing area of woodland cover and milder
winters potentially having a beneficial impact for some species.
For more information about the evidence for this indicator, see the evidence statement
‘Annex 1.04 Evidence Statement for C5b Woodland Birds’.
Species breakdown
The woodland bird index is comprised of trends for 34 species. The relatively stable trend
for all woodland birds from the late 1990s masks different underlying trends for specialist
species, which are highly dependent on woodland habitats; and generalist species, which
are found in a wide range of habitats, including woodland.
The long-term decline of the woodland bird indicator in England has been mostly driven by
the decline of specialist woodland birds. Between 1970 and 2019, the index for woodland
specialists declined by 41% while the index for woodland generalists increased by 7%.
The smoothed trend (between 1970 and 2018) shows a significant decline of 40% for
specialists and zero change for woodland generalists (figure 3a).
Figure 3a: Breeding woodland birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trends (dashed lines) and smoothed trends (solid lines).
Woodland specialists
For 9 species of the woodland specialists their numbers have more than halved since
1970, with 4 species (lesser redpoll, willow tit, spotted flycatcher and tree pipit) having
declined by 90% or more. By contrast, populations of 6 woodland specialists (blackcap,
chiffchaff, great spotted woodpecker, green woodpecker, nuthatch and sparrowhawk) have
more than doubled since 1970. However, the great spotted woodpecker showed little
change in the short term and numbers for both the green woodpecker and sparrowhawk
showed strong declines since 2013.
The smoothed index for specialists shows a significant 10% decline between 2013 and
2018. However, species within it show markedly different trends over this 5-year period.
Lesser redpoll and wood warbler have decreased by over 30%, whereas nuthatch and
blackcap show increases of 17% and 14% respectively between 2013 and 2018.
Figure 3b: Breeding specialist woodland birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Overall, 32% of the 22 specialist species in the woodland indicator increased, 27%
showed little change and 41% declined over the long-term period.
Short term
In the short term, 18% of all specialist woodland species increased, 23% showed little
change and 59% declined, with half of these species showing a strong decline.
Woodland generalists
The majority of generalist woodland species, many of which have adapted to using gardens
and wooded areas in farmland, have not shown any change over the long term.
Figure 3c: Breeding generalist woodland birds in England, 1970 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
The majority of generalist species showed little change, whilst song thrush and bullfinch
showed weak declines of 51% and 42% respectively. In contrast, populations of great tit,
long-tailed tit, robin and wren have increased by more than 50% since 1970.
Short term
The smoothed index shows a non-significant 2% increase between 2013 and 2018 for
generalist woodland species. One of the 12 species decreased over this short-term period;
chaffinch by 28%. Wren and lesser whitethroat increased by 18% and 15% respectively in
the short term.
4. Breeding water and wetland bird populations in England
Water and wetlands6 include rivers, lakes, ponds, reedbeds, grazing marshes, other wet
grasslands, and lowland raised bogs, all providing important habitats for birds [Footnote 6:
Species included in the wetland indicator are those defined as having a positive association with waterways
or wetlands, but in practice, these overlap markedly with those classified as ‘lowland wetland’ species and
also include some upland birds and those also associated with farmland, for example reed bunting and
yellow wagtail].
Produced largely using the population trends from surveys in wetland habitats, the water
and wetland bird index has remained fairly stable for most of the period since data
collection started in 1975. In 2019 the water and wetland bird index was 1% higher than
the 1975 baseline. Numbers rose slightly in the early 2000s then fell; the smoothed index
showed a non-significant 1% increase between 2013 and 2018.
Figure 4: Breeding water and wetland birds in England, 1975 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
6 Species included in the wetland indicator are those defined as having a positive association with waterways
or wetlands, but in practice, these overlap markedly with those classified as ‘lowland wetland’ species and also
include some upland birds and those also associated with farmland, for example reed bunting and yellow
wagtail.
Long term
Of the 25 species for which a long-term trend can be calculated, 28% of species
increased, 48% showed little change and 24% declined, with the majority of species
exhibiting a change show a weak rather than a strong change. For little egret, data can
only be included from 2004 and therefore a long-term trend could not be calculated (for
more information on the time series used for different species long-term trends, see Annex
A).
Short term
Over the short-term period between 2013 and 2018, 27% of species increased, 35%
showed little change and 38% declined.
Factors affecting water and wetland bird populations
The historical declines in breeding waders resulted from land management changes such
as drainage, the intensification of grassland management and the conversion of coastal
and floodplain grazing marshes to arable land. Where populations persist in small
fragments of high-quality habitat, their nests and young can be vulnerable to predation,
which is currently thought to be limiting the recovery of several species of breeding wader.
However, a range of species, particularly those associated with standing water bodies,
have benefitted from habitat creation, particularly from the restoration of post-extraction
gravel pits. Additionally, there has been a net positive impact from improved survival rates
due to the trend towards milder winters.
For more information about the evidence for this indicator, see the evidence statement
‘Annex 1.05 Evidence Statement for C5c Wetland Birds’.
Species breakdown
The 26 species of bird included in the water and wetland bird index can be split into 4
categories for producing sub-habitat indicators. Although the index for all wetland and
waterways species shows a relatively stable trend, this masks underlying and marked
differences between sub-habitat indicators (figure 4a). When interpreting these trends, it
should be borne in mind that each sub-habitat trend is derived from relatively few species’
trends.
Figure 4a: Breeding water and wetland birds in England, 1975 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trends (dashed lines) and smoothed trends (solid lines),
iii) the number of species in each of the sub indicators do not sum to the all species indicator because 4
species in the main breeding wetland and waterways indicator are not included in any of the sub-indicators
covering birds of reed beds, fast flowing waterways, standing and slow-flowing waterways, or wet
grasslands. These are sand martin, kingfisher, grey heron and oystercatcher. None of these species show a
strong preference for any one of those habitats, either being fairly generalist or with large proportions of their
populations in other habitats such as coasts (e.g. oystercatcher).
Birds of slow flowing and standing water
Birds of slow flowing and standing water show the most positive trend, potentially
benefitting most from wetland creation, with the index increasing by 43% since 1975
(Figure 4b). However, the smoothed indicator shows a significant 9% decline between
2013 and 2018. The long-term increase was driven by 2 duck species, (mallard and tufted
duck), each doubling in numbers. Great crested grebe showed a weak decline. Numbers
for moorhen and little grebe show little change since 1975.
Figure 4b: Breeding slow flowing and standing waterbirds in England, 1975 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Overall, 2 of the 6 species showed a weak increase in the long term, 3 showed little
change and one showed a weak decrease.
Short term
In the short term one species increased, one showed little change and 4 species declined
(the majority showed a strong decline). Numbers of little grebe showed a 7% increase
between 2013 and 2018. Numbers of tufted duck, coot and great crested grebe all
declined strongly by 19%, 15% and 13% respectively in the short term.
Birds of fast flowing water
The index for birds of fast flowing water was 17% lower in 2019 than in 1975. Numbers
dipped during 2009 to 2014, although not as low as in the early 1980s. The index has
recovered in the most recent years and between 2013 and 2018 it increased, not
significantly by 3% (Figure 4c).
Figure 4c: Breeding birds of fast flowing water in England, 1975 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Numbers of goosander have increased by 86% since 1981 (when data for this species
began). However, numbers of dipper, grey wagtail and common sandpiper show little
change compared to their 1975 baseline levels.
Short term
One of the four species increased in the short term (2013 to 2018); grey wagtail increased
by 23%. Both common sandpiper and goosander show little change since 2013. Numbers
of dipper showed a 6% decrease in the short term.
Birds of reedbeds
The index for birds of reedbeds has fluctuated over the long-term period, and in 2019 was
1% lower than in 1975 (Figure 4d). The smoothed index peaked in 2009 and showed a 1%
decrease over the short term between 2013 and 2018.
Figure 4d: Breeding birds of reedbeds in England, 1975 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
In the long term, reed bunting and sedge warbler showed declines of 56% and 48%
respectively, contrasting with a 7-fold increase in Cetti’s warbler since 1988 (when the
species exceeded the 300 pair threshold for inclusion in the indicator, following the
colonisation of the UK in 1972), and reed warbler showed little change.
Short term
Over the short-term, numbers of sedge warbler have declined strongly, falling by 15%
between 2013 and 2018. Reed bunting numbers have also fallen by 13% in the short term.
Cetti’s warbler has continued to increase strongly, by 30% between 2013 and 2018, and
reed warbler has shown little change.
Birds of wet grassland
The index of birds of wet grassland decreased by 31% compared to 1975 (Figure 4e).
The majority of the decline occurred between the mid-1980s and the mid-1990s. More
recently the indicator has levelled off; the smoothed indicator shows a non-significant
10% increase between 2013 and 2018.
Figure 4e: Breeding birds of wet grassland in England, 1975 to 2019
Notes:
i) figures in brackets show the number of species,
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line) with its 95% confidence
interval (shaded area).
Long term
Over the long term, although some wet grassland species (mute swan and teal) increased,
3 species declined, and 2 species showed little changed. Of the 3 species which declined,
one species, the yellow wagtail, has declined strongly by 97% in riverine habitats
compared to their 1975 baseline. Snipe and redshank have also decreased, by 67% and
58% respectively, since 1975.
Short term
Over the short term, both yellow wagtail and redshank show strong declines of 20% and
14% respectively between 2013 and 2018. Snipe trends have reversed, showing a strong
short-term increase of 42% in contrast to its long-term decline. Lapwing numbers show
little change, both in the long and short term. Little egret, which was included for the first
time in 2006 (when the population first exceeded the 300 pair lower threshold for inclusion)
and therefore not assessed over the long term, showed a strong increase of 54% since
2013.
5. Breeding seabird populations in England
The breeding seabird index has now been updated with data up to and including 2019.
In addition to the annual monitoring scheme (Seabird Monitoring Programme; SMP),
JNCC is working, in association with other SMP partners, on the completion of the
next breeding seabird census, Seabirds Count (2015-2021) across Britain and
Ireland. Regular counts at a sample of colonies provide robust trends, but entire
population censuses are also required to add context and help to identify why
changes might be happening, as well as to enable the calculation of between-census
trends for those seabird species not monitored by the annual sample surveying.
Additionally, conducting periodic censuses allows the accuracy of SMP annual
monitoring trends to be tested and the opportunity to understand how breeding
seabird populations might be changing spatially. This is especially important when
considering inland and urban breeding species, which are rarely monitored annually.
The seabird figures are based on very recently updated data and are presented with
unsmoothed confidence intervals. Smoothed trends and assessments of change
based on smoothed trends will be calculated subsequently.
The English coast consists of a wide variety of habitats such as sea cliffs, sand dunes,
shingle ridges and intertidal areas. The marine habitats used for foraging by this group of
birds include coastal lagoons and shallow coastal waters as well as deeper offshore
waters throughout the UK. Although inland populations are largely excluded, some species
will also exploit terrestrial food sources.
In 2019, the breeding seabird index in England was 11% higher than in 1986. The
indicator has increased to the current level between 1986 and about 1992 since when it’s
been stable with fluctuations. In the short term, the index increased by 4% between 2013
and 2018.
Figure 5: Breeding seabirds in England, 1986 to 2019
Notes:
i) figures in brackets show the number of species.
ii) graph shows 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.
Long term
Between 1986 and 2018, 18% of the 11 seabird species increased, 45% showed little
change and 36% declined, the majority of the latter show a weak decline.
Short term
Over the short-term period between 2013 and 2018, 55% of the species increased, 9%
showed little change and 36% declined.
Figure 5a: Breeding surface and subsurface feeding seabirds in England, 1986 to
2019
Notes:
i) figures in brackets show the number of species.
ii) graph shows unsmoothed trend (dashed line) - no smoothed trend is available for seabirds, but this will be
available in future publications.
Species breakdown
Long term
There are 11 species of bird included in the England seabird indicator. This includes
gannet, which has shown a rapidly increasing trend at the only English colony at
Bempton Cliffs, Yorkshire, which has had a marked positive effect on the indicator. A
breakdown by feeding behaviour (Figure 5a) shows a 22% decline in seabirds that
forage on the surface of the sea (surface piscivores) in contrast with a 168% increase
in those that forage by diving (subsurface piscivores). Numbers of herring gull, the
European shag, little tern and black-legged kittiwake have all declined by 75%, 53%,
44% and 41% respectively in the long term. In contrast, numbers of common guillemot
and gannet show a strong increase; common guillemot numbers have more than
doubled and gannet numbers increased 20-fold between 1986 and 2018.
Short term
Over the short term between 2013 and 2018, sandwich tern, Arctic tern, common tern
and gannet all show strong increases between 2013 and 2018. Numbers of little tern,
European shag, and herring gull continue to decline strongly, falling more than 15%
between 2013 and 2018.
This 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 5km 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. Work is currently underway to improve survey coverage of inland colonies so
that a trend based on all breeding areas can be included in the ‘all species indicator’.
The seabird index in England continues to show a different pattern to the UK seabird
index7 [Footnote 7: The UK seabird trend can be seen in the Defra National Statistics Release, Wild bird
populations in the UK, 1970 to 2019, also published today]. One reason for this difference is species
composition. Some species breed only in Scotland whereas others are more widespread
but have the bulk of their populations in northern parts of the British Isles, and there may
be insufficient data to generate an England-only trend. Furthermore, it was also possible to
generate an England trend for gannet based on reliable data from a single large colony, but
there are insufficient data representative of the UK population to produce a reliable UK trend
for this species.
For more information about the evidence for this indicator, see the evidence statement
‘Annex 1.06 Evidence Statement for C5d Seabirds’.
7 The UK seabird trend can be seen in the Defra National Statistics Release, Wild bird populations in the UK,
1970 to 2019, also published today.
6. Wintering waterbird populations in England
The term waterbird refers to birds that inhabit or depend on water and wetland habitats;
this chapter is about waterbirds that over-winter in England, some of which also breed in
England8 [Footnote 8: Not all of the wintering waterbirds in this chapter are included in the all breeding
birds index, only those which also breed in England and for which breeding trends are available. In Annex A
those species that overlap are included under both].
In the winter of 2018/19, the wintering waterbird index was 76% higher than in 1975/76.
The index peaked in the late 1990s, and has declined since, with the smoothed index
falling 6% in the short term between 2012/13 and 2017/18.
Figure 6: Wintering waterbirds in England, 1975/76 to 2018/19
Notes:
i) figures in brackets show the number of species.
ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line). Data from surveys
of wintering waterbirds are based largely on full counts at colonies or 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.
iii) the number of species in each sub indicator do not sum to the number in the all-species indicator because
4 species are included in all wintering waterbirds but are neither wildfowl nor wader. These are 2 grebes
(little and great-crested), one rail species (coot) and cormorant. These are in 3 different taxonomic groups
none large enough to warrant a separate indicator.
8 Not all of the wintering waterbirds in this chapter are included in the all breeding birds index, only those which
also breed in England and for which breeding trends are available. In Annex A those species that overlap are
included under both.
Long term
Since 1975/76, 46% of wintering waterbird species increased, 37% showed little change
and 17% declined, most of these showing a weak decline.
Short term
Over the short-term period between the winters of 2012/13 and 2017/18, 24% of species
increased, 37% showed little change and 39% declined.
Factors affecting wintering wetland bird populations
Breeding wintering wetland birds are affected by a range of factors including conditions in
the high latitude countries where they breed, with breeding productivity increasing for
species including black-tailed godwit but decreasing for others such as Greenland white-
fronted geese. There is good evidence of a strong climate change impact on the indicator
in recent years, with milder winters leading to the wintering ranges of some species, such
as ringed plovers, increasingly shifting away from the UK. In addition, local changes, such
as wetland creation and changes in agricultural management, have had an impact on
waterbird populations within the UK.
For more information about the evidence for this indicator, see the evidence statement
‘Annex 1.07 Evidence Statement for C5e Wintering Waterbirds’.
Species breakdown
There are 41 species, races and populations of bird included in the wintering waterbird
indicator. These can be split into subcategories of wildfowl (ducks, geese and swans) and
waders (sandpipers, plovers and their close relatives) which display slightly different
trends. Overall, the smoothed wildfowl index has increased by 90% and the wader index
has increased 51% between 1975/76 and 2017/18. However, both peaked in the late
1990s and between 2012/13 and 2017/18, both the smoothed indices for waders and
wildfowl declined by 3% and 11% respectively.
Wildfowl
Long term
Since the winter of 2017/18, half of the wildfowl species increased, 27% showed little
change and 23% declined. Notable strong increases included Whooper swan, gadwall and
British/Irish greylag goose, which increased greatly by 22, 15 and 13-fold respectively in
the long term. Numbers of scaup have declined strongly by 83% since 1975/76. There
were also long-term declines for wildfowl species: European white-fronted goose, Bewick’s
swan, pochard and eider of 61%, 56%, 55% and 48% respectively.
Short term
Between the winters of 2012/13 and 2017/18, 23% of species in the wildfowl indicator
increased, 18% showed little change and 59% declined. The majority of species in the
wildfowl indicator declined, with Bewick’s swan, red-breasted merganser and eider
declining strongly by 48%, 34% and 32% respectively over this short-term period. The
indices for both shoveler and pink-footed goose increased strongly by 22% and 16%
respectively between the winters of 2012/13 and 2017/18.
Waders
Long term
Since the winter of 2017/18, 33% of species in the wader index increased, 53% showed
little change and 13% declined The indices for both avocet and black-tailed godwit
increased strongly by 8 and 7-fold respectively in the long term In contrast, numbers of
ringed plover and dunlin decreased by 52% and 50% respectively since 1975/76.
Short term
Between the winters of 2012/13 and 2017/18, 13% of wader species increased, 73%
showed little change and 13% declined. Both indices for curlew and bar-tailed godwit
showed strong declines of 21% and 17% respectively. The indices for sanderling and
black-tailed godwit increased weakly by 13% and 6% respectively.
Main notes: methodological detail, limitations of the indicators and further information
1. The bird population indices have been compiled in conjunction with the British Trust for
Ornithology (BTO), the Joint Nature Conservation Committee (JNCC), the Wildfowl and
Wetlands Trust (WWT), and the Royal Society for the Protection of Birds (RSPB) from
a wide range of sources, principally:
• the Common Birds Census (from 1966 to 2000),
• the BTO/JNCC/RSPB Breeding Bird Survey (from 1994 to 2019),
• the BTO/ Waterways Bird Survey (from 1974 to 2007),
• the BTO/JNCC/RSPB Waterways Breeding Bird Survey, with support from the
Environment Agency (from 1998 to 2019),
• the BTO/RSPB/JNCC Wetland Bird Survey counts (from 1975/76 to 2018/19),
• the WWT Goose & Swan Monitoring Programme in partnership with the JNCC
and Scottish Natural Heritage,
• the Seabird Monitoring Programme (from 1986 to 2019),
• the Periodic Seabird censuses supplied by JNCC, RSPB, the Seabird Group,
SOTEAG (Shetland Oil Terminal Environmental Advisory Group) and other
partners,
• Monitoring of scarce and rare breeding birds by the Statutory Conservation
Agency and RSPB Annual Breeding Bird Scheme (SCARABBS) and the Rare
Breeding Birds Panel (from 1970 to 2018).
The census sources provide an indication of the average annual rate of change
between censuses for some species, and this is assumed to apply to each year
between censuses.
More information about individual species trends, including photographs, and
background to the changes in population are available via the BTO website. Some
regional analysis is also published as part of the Breeding Bird Survey, including for
other constituent countries of the UK. More information about the State of UK birds
can be accessed through the RSPB website. Details on the monitoring of scarce
and rare breeding birds, including annual reports, can be found on the website of
the Rare Breeding Birds Panel.
2. The indices cover birds that are native to the England, excluding rare (less than 300
breeding pairs) and introduced species. The indices portray the annual changes in
abundance. Within the indices, each species is given equal weighting, and the overall
index is the geometric mean of the individual species indices. Individual species
populations within the index may be increasing or decreasing, irrespective of the
overall index trends. Species indices are derived by modelling count data and
estimates are revised when new data or improved methodologies are developed and
applied retrospectively to earlier years.
3. The indices are considered to give reliable medium to long-term trends but strong
reliance should not be attached to short-term changes from year to year.
4. The individual species included within each indicator are given in Annex A.
5. Smoothing is a standard procedure in the generation and reporting of bird population
trends (www.bto.org/birdtrends2010/methodology.htm). The smoothing methodology
involves the application of a thin plate smoothing spline to remove the short-term peaks
and troughs due to weather effects and any between year sampling error. Research by
the BTO and RSPB further developed this procedure to enable the production of an
indicator based on smoothed individual species’ indices.
6. Bootstrapping, a standard statistical technique, is used to calculate 95% confidence
intervals in the indicators and in change over any specified period. The width of the
confidence interval for a given indicator is influenced by the number of species in that
indicator and the precision of the individual species trends that make up that indicator.
The precision of trends varies between species; this is true even for species for which
trends come from the same source, due to the variation in sample size. Therefore, the
size of confidence intervals varies among habitat indicators.
7. For the farmland bird index, it should be noted that although 20 species were originally
chosen for the index, a reliable annual index is not available for barn owl, so that
species is excluded.
8. Details of agri-environmental schemes designed to improve environmental
management in farming can be found via the following administrating bodies:
• Natural England
9. Defra previously also published an annual National Statistics Release, Wild bird
population indicators for the English regions. This Release was discontinued in 2011,
as a result of resource constraints and changes in regional governance. The last
release9 covered trends for 1994 to 2008 and was published in 2010 [Footnote 9:
www.defra.gov.uk/statistics/files/wdbrds2010004.pdf]. However, these statistical releases drew
upon results from the Joint BTO/JNCC/RSPB Breeding Bird Survey and some regional
analysis will continue to be published as part of the Breeding Bird Survey, including for
the other constituent countries of the UK.
9 www.defra.gov.uk/statistics/files/wdbrds2010004.pdf
36
Annex A: Trends in bird species, by habitat10 group, in England
[Footnote 10: Habitat classifications are generally based on ‘Gibbons, D.W., Reid, J.B. & Chapman, R. A. 1993. The New Atlas of Breeding Birds in Britain and Ireland:
1988 to 1991. London: T. & A.D. Poyser]
The tables below list the species that are included in each indicator. Percentage changes are based on smoothed data, except in the
case of seabirds, for which no smoothed trend data are available. Annual percentage change represents the rate of change over the time
period shown, allowing the assessment of strong or weak to be made. ‘Strong’, ‘weak’, ‘little change’ is determined by how much the
population would change if the average rate of annual change (over the specified period, long or short term) continued for 25 years.
Farmland (19)
Generalists (7) Long-term change (1970-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Greenfinch (Chloris chloris) -62 -2 weak decline -46 -11.5 strong decline
Jackdaw (Corvus monedula) 155 1.97 weak increase 10 1.9 weak increase
Kestrel (Falco tinnunculus) -31 -0.76 little change 1 0.16 little change
10 Habitat classifications are generally based on ‘Gibbons, D.W., Reid, J.B. & Chapman, R. A. 1993. The New Atlas of Breeding Birds in Britain and Ireland: 1988 to
1991. London: T. & A.D. Poyser.
37
Reed Bunting (Emberiza schoeniclus)
-29 -0.71 little change 4 0.72 little change
Rook (Corvus frugilegus) 16 0.35 little change 0 -0.03 little change
Woodpigeon (Columba palumbus) 133 1.78 weak increase -3 -0.53 little change
Yellow wagtail (Motacilla flava) -65 -2.19 weak decline -1 -0.16 little change
Specialists (12) Long-term change (1970-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Corn bunting (Emberiza calandra) -89 -4.44 strong decline 5 0.94 little change
Goldfinch (Carduelis carduelis) 174 2.12 weak increase 19 3.6 strong increase
Grey partridge (Perdix perdix) -93 -5.31 strong decline -19 -4.18 strong decline
Lapwing (Vanellus vanellus) -53 -1.55 weak decline -4 -0.72 little change
Linnet (Carduelis cannabina) -63 -2.06 weak decline 2 0.43 little change
Skylark (Alauda arvensis) -61 -1.96 weak decline -1 -0.26 little change
Starling (Sturnus vulgaris) -88 -4.26 strong decline -2 -0.32 little change
Stock dove (Columba oenas) 112 1.58 weak increase 21 3.87 strong increase
Tree sparrow (Passer montanus) -96 -6.31 strong decline -9 -1.81 weak decline
Turtle dove (Streptopelia turtur) -98 -7.94 strong decline -42 -10.38 strong decline
Whitethroat (Sylvia communis) -16 -0.37 little change -14 -2.91 strong decline
Yellowhammer (Emberiza citrinella) -66 -2.2 weak decline -11 -2.37 weak decline
38
Woodland (34)
Generalists (12) Long-term change (1970-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Blackbird (Turdus merula) -18 -0.4 little change 2 0.37 little change
Blue tit (Cyanistes caeruleus) 19 0.36 little change -2 -0.39 little change
Bullfinch (Pyrrhula pyrrhula) -42 -1.14 weak decline 3 0.67 little change
Chaffinch (Fringilla coelebs) -5 -0.11 little change -28 -6.31 strong decline
Dunnock (Prunella modularis) -36 -0.92 little change -2 -0.37 little change
Great tit (Parus major) 73 1.15 weak increase 2 0.39 little change
Lesser whitethroat (Sylvia curruca) 22 0.41 little change 15 2.9 strong increase
Long-tailed tit (Aegithalos caudatus)
71 1.12 little change 5 0.95 little change
Robin (Erithacus rubecula) 64 1.04 little change 8 1.53 weak increase
Song thrush (Turdus philomelos) -51 -1.5 weak decline 10 1.91 weak increase
Tawny owl (Strix aluco) -36 -0.93 little change 1 0.15 little change
Wren (Troglodytes troglodytes) 60 0.99 little change 18 3.29 strong increase
39
Specialists (22) Long-term change (1970-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Blackcap (Sylvia atricapilla) 292 2.89 strong increase 14 2.7 weak increase
Chiffchaff (Phylloscopus collybita) 102 1.48 weak increase 3 0.65 little change
Coal tit (Periparus ater) 38 0.67 little change 9 1.75 weak increase
Garden warbler (Sylvia borin) -17 -0.39 little change 0 -0.06 little change
Goldcrest (Regulus regulus) -18 -0.42 little change 8 1.47 weak increase
Great spotted woodpecker (Dendrocopos major)
307 2.97 strong increase -4 -0.89 little change
Green woodpecker (Picus viridis) 103 1.49 weak increase -15 -3.24 strong decline
Jay (Garrulus glandarius) -4 -0.09 little change -10 -2.13 weak decline
Lesser spotted woodpecker (Dendrocopos minor)
-70 -2.47 weak decline -8 -1.56 weak decline
Marsh tit (Poecile palustris) -73 -2.66 weak decline -5 -1.12 little change
Nightingale (Luscinia megarhynchos)a
-55 -3.45 strong decline -27 -6.19 strong decline
Nuthatch (Sitta europaea) 307 2.97 strong increase 17 3.27 strong increase
Lesser redpoll (Carduelis cabaret) -95 -6.21 strong decline -31 -7.16 strong decline
Redstart (Phoenicurus phoenicurus)
28 0.51 little change -17 -3.55 strong decline
Sparrowhawk (Accipiter nisus) 114 1.6 weak increase -21 -4.64 strong decline
Spotted flycatcher (Muscicapa striata)
-93 -5.48 strong decline -18 -3.89 strong decline
Wood warbler (Phylloscopus sibilatrix)a
-84 -7.54 strong decline -39 -9.29 strong decline
Siskin (Carduelis spinus)a 56 1.96 weak increase -10 -2.08 weak decline
Tree pipit (Anthus trivialis) -90 -4.62 strong decline -21 -4.53 strong decline
40
Treecreeper (Certhia familiaris) -14 -0.32 little change 3 0.5 little change
Willow tit (Poecile montana) -94 -5.73 strong decline -12 -2.63 weak decline
Willow warbler (Phylloscopus trochilus)
-67 -2.3 weak decline -13 -2.65 weak decline
a Data for the long-term assessment are from 1995 to 2018
41
Water and wetland birds (26)
Birds of fast flowing water (4) Long-term change (1975-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Common sandpiper (Actitis hypoleucos)
-35 -0.99 little change 0 -0.07 little change
Dipper (Cinclus cinclus) -19 -0.5 little change -6 -1.25 weak decline
Goosander (Mergus merganser)b 86 1.69 weak increase -1 -0.19 little change
Grey wagtail (Motacilla cinerea) -34 -0.95 little change 23 4.28 strong increase
b Data for the long-term assessment are from 1981 to 2018
Birds of reedbeds (4)
Long-term change (1975-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Cetti's warbler (Cettia cetti)c 636 7.12 strong increase 30 5.37 strong increase
Reed bunting (Emberiza schoeniclus)
-56 -1.89 weak decline -13 -2.69 weak decline
Reed warbler (Acrocephalus scirpaceus)d
41 0.93 little change 0 0 little change
Sedge warbler (Acrocephalus schoenobaenus)
-48 -1.53 weak decline -15 -3.24 strong decline
c Data for the long-term assessment are from 1989 to 2018 d Data for the long-term assessment are from 1981 to 2018
42
Birds of slow and standing water (6)
Long-term change (1975-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Coot (Fulica atra) 57 1.06 little change -15 -3.13 strong decline
Great crested grebe (Podiceps cristatus)e
-30 -1.52 weak decline -13 -2.77 strong decline
Little grebe (Tachybaptus ruficollis) -9 -0.22 little change 7 1.28 weak increase
Mallard (Anas platyrhynchos) 153 2.18 weak increase -10 -2.18 weak decline
Moorhen (Gallinula chloropus) -23 -0.59 little change -3 -0.53 little change
Tufted duck (Aythya fuligula) 87 1.47 weak increase -19 -4.06 strong decline
e Data for the long-term assessment are from 1995 to 2018
Birds of wet grassland (8)
Long-term change (1975-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Curlew (Numenius arquata)f -15 -0.43 little change 1 0.21 little change
Lapwing (Vanellus vanellus)f 0 -0.01 little change -4 -0.77 little change
Little egret (Egretta garzetta) N/A N/A N/A 54 9.02 strong increase
Mute swan (Cygnus olor) 118 1.83 weak increase 4 0.74 little change
Redshank (Tringa totanus) -58 -1.97 weak decline -14 -2.86 strong decline
Snipe (Gallinago gallinago) -67 -2.55 weak decline 42 7.21 strong increase
Teal (Anas crecca)g 237 5.43 strong increase 45 7.76 strong increase
Yellow wagtail (Motacilla flava) -97 -7.67 strong decline -20 -4.39 strong decline
43
f Data for the long-term assessment are from 1980 to 2018 g Data for the long-term assessment are from 1995 to 2018
Other (4)
Long-term change (1975-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Grey heron (Ardea cinerea) -21 -0.54 little change -2 -0.46 little change
Kingfisher (Alcedo atthis) -24 -0.63 little change -6 -1.24 weak decline
Oystercatcher (Haematopus ostralegus)
167 2.31 weak increase -2 -0.44 little change
Sand martin (Riparia riparia)h 19 0.43 little change 7 1.33 weak increase
h Data for the long-term assessment are from 1978 to 2018
44
Seabird (11)
Long-term change (1986-2018) Short-term change (2013-2018)
Species Long-term percentage change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Black-legged kittiwake (Rissa tridactyla)
-41 -1.64 weak decline 15 2.81 weak increase
Common guillemot (Uria aalge) 147 2.86 strong increase 1 0.25 little change
European shag (Phalacrocorax artistotelis)
-53 -2.33 weak decline -21 -4.61 strong decline
Great cormorant (Phalacrocorax carbo)
16 0.47 little change 14 2.61 weak increase
Herring gull (Larus argentatus) -75 -4.19 strong decline -15 -3.25 strong decline
Northern fulmar (Fulmarus glacialis)
-27 -0.98 little change -9 -1.76 weak decline
Common tern (Sterna hirundo) 4 0.13 little change 18 3.33 strong increase
Sandwich tern (Sterna sandvicensis)
8 0.24 little change 40 7.26 strong increase
Little tern (Sternula albifrons) -44 -1.78 weak decline -18 -3.85 strong decline
Arctic tern (Sterna paradisaea) 35 0.93 little change 25 4.64 strong increase
Gannet (Morus bassanus) 1960 9.92 strong increase 16 3.02 strong increase
45
Wintering waterbirds (41)
Wildfowl (22) Long-term change (1975/76-2017/18) Short-term change (2012/13-2017/18)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Mute swan (Cygnus olor) 209 2.72 weak increase 1 0.26 little change
Bewick's swan (Cygnus columbianus)
-56 -1.95 weak decline -48 -12.42 strong decline
Whooper swan (Cygnus cygnus) 2095 7.63 strong increase 12 2.38 weak increase
Pink-footed goose (Anser brachyrhynchus)
436 4.08 strong increase 16 3.01 strong increase
White-fronted goose, European (Anser albifrons ablbifrons)
-61 -2.22 weak decline -25 -5.65 strong decline
Greylag goose, British/Irish (Anser anser anser)i
1222 6.34 strong increase 10 2 weak increase
Brent goose, Dark-bellied (Branta bernicla bernicla)
151 2.22 weak increase -8 -1.71 weak decline
Brent goose, Svalbard light-bellied (Branta bernicla hrota)
808 5.39 strong increase -22 -4.9 strong decline
Shelduck (Tadorna tadorna)j 28 0.58 little change 8 1.51 weak increase
Wigeon (Anas penelope) 165 2.35 weak increase 0 0.09 little change
Gadwall (Anas strepera) 1436 6.72 strong increase -1 -0.15 little change
Teal (Anas crecca)k 142 2.13 weak increase -8 -1.74 weak decline
Mallard (Anas platyrhynchos) -24 -0.65 little change -12 -2.6 weak decline
Pintail (Anas acuta) -29 -0.83 little change 5 1.06 little change
Shoveler (Anas clypeata) 145 2.16 weak increase 22 4.07 strong increase
Pochard (Aythya ferina) -55 -1.86 weak decline -23 -4.99 strong decline
Tufted duck (Aythya fuligula) 54 1.03 little change -10 -2.05 weak decline
Scaup (Aythya marila) -83 -4.16 strong decline -15 -3.22 strong decline
46
Eider, except shetland (Somateria mollissima)
-48 -2.3 weak decline -32 -7.49 strong decline
Goldeneye (Bucephala clangula) 23 0.49 little change -22 -4.82 strong decline
Red-breasted merganser (Mergus serrator)
35 0.72 little change -34 -8.02 strong decline
Goosander (Mergus merganser) 112 1.8 weak increase -11 -2.32 weak decline I Data for the long-term assessment are from 1982/83 to 2017/18 J Data for the long-term assessment are from 1988/89 to 2017/18 k Data for the long-term assessment are from 1987/88 to 2017/18
Wader (15) Long-term change (1975/76-2017/18) Short-term change (2012/13-2017/18)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Oystercatcher (Haematopus ostralegus)
-16 -0.42 little change -1 -0.19 little change
Avocet (Recurvirostra avosetta)l 738 7.89 strong increase 4 0.75 little change
Ringed plover (Charadrius hiaticula) -52 -1.73 weak decline 4 0.73 little change
Golden plover (Pluvialis apricaria) 200 2.65 weak increase 5 1.03 little change
Grey plover (Pluvialis squatarola) 150 2.2 weak increase -5 -1.09 little change
Lapwing (Vanellus vanellus) 114 1.83 weak increase 3 0.53 little change
Knot (Calidris canutus) 9 0.21 little change -5 -0.99 little change
Sanderling (Calidris alba) 42 0.85 little change 13 2.45 weak increase
Purple sandpiper (Calidris maritima) 11 0.26 little change -5 -1.05 little change
Dunlin (Calidris alpina) -50 -1.63 weak decline -4 -0.87 little change
Black-tailed godwit (Limosa limosa) 646 4.9 strong increase 6 1.21 weak increase
Bar-tailed godwit (Limosa lapponica)
-7 -0.18 little change -17 -3.61 strong decline
47
Curlew (Numenius arquata) -14 -0.36 little change -21 -4.6 strong decline
Redshank (Tringa totanus) 2 0.05 little change -5 -0.96 little change
Turnstone (Arenaria interpres) -11 -0.27 little change -5 -0.99 little change
l Data for the long-term assessment are from 1988/89 to 2017/18
Other (4) Long-term change (1975/76-2017/18) Short-term change (2012/13-2017/18)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Coot (Fulica atra)m 3 0.09 little change -15 -3.29 strong decline
Cormorant (Phalacrocorax carbo)n 129 2.89 strong increase 26 4.77 strong increase
Great crested grebe (Podiceps cristatus)m
55 1.38 weak increase 6 1.26 weak increase
Little grebe (Tachybaptus ruficollis)o 117 2.8 weak increase 11 2.04 weak increase
m Data for the long-term assessment are from 1984/85 to 2017/18 n Data for the long-term assessment are from 1987/88 to 2017/18 o Data for the long-term assessment are from 1988/89 to 2017/18
48
Other birds included in the all-species index (31)
The all-species line is comprised of all 118 available population trends for widespread breeding species in England, from all landscape
types. It excludes rare species (with less than 300 breeding pairs) and all species for which no England trend information is available.
The species composition of all species index (118 species) includes:
• 19 farmland* species trends (i.e. those in the farmland bird index);
• 34 woodland bird species (i.e. those in the woodland bird index);
• 26 breeding wetland* species (i.e. those in the breeding birds of water and wetlands index);
• 11 seabirds, and;
• 31 other species trends, including birds of urban areas, heathlands, uplands, coasts and species with no strong habitat
preferences (generalists). Some of these birds are also included under wintering waterbirds but are included here as they also
breed in the England and are included in the all-species index.
* Note that trends for 3 species (yellow wagtail, reed bunting and lapwing) are included in 2 separate habitat-specific indicators (farmland and breeding wetland) due to their reliance
on both of these habitats. The same trends as used in the farmland bird indicator are used for these 3 species in the all-species indicator to avoid duplication.
Long-term change (1970-2018) Short-term change (2013-2018)
Species Long-term percentage
change
Annual percentage
change
Trend Short-term percentage
change
Annual percentage
change
Trend
Avocet (Recurvirostra avosetta)p 424 0.06 strong increase 25 0.04 strong increase
Bearded tit (Panurus biarmicus) 28 0.01 little change -6 -0.01 weak decline
Black-headed gull (Chroicocephalus ridibundus)
88 0.01 weak increase -1 0.00 little change
Buzzard (Buteo buteo) 1069 0.05 strong increase 15 0.03 strong increase
Carrion crow (Corvus corone) 110 0.02 weak increase 0 0.00 little change
Cirl bunting (Emberiza cirlus)q 97 0.04 strong increase 17 0.03 strong increase
Collared dove (Streptopelia decaocto)
819 0.05 strong increase -14 -0.03 strong decline
49
Cuckoo (Cuculus canorus) -77 -0.03 strong decline -9 -0.02 weak decline
Dartford warbler (Sylvia undata)r 157 0.02 weak increase 67 0.11 strong increase
Firecrest (Regulus ignicapilla) -100 0.00 Not available 8 0.01 weak increase
Hobby (Falco subbuteo)s -27 -0.01 weak decline -14 -0.03 strong decline
House martin (Delichon urbicum)s -40 -0.02 weak decline -13 -0.03 weak decline
House sparrow (Passer domesticus)
-74 -0.03 strong decline 1 0.00 little change
Magpie (Pica pica) 103 0.01 weak increase -1 0.00 little change
Meadow pipit (Anthus pratensis) -52 -0.02 weak decline -13 -0.03 strong decline
Mediterranean gull (Larus melanocephalus)
-100 0.00 Not available 160 0.21 strong increase
Mistle thrush (Turdus viscivorus) -63 -0.02 weak decline -1 0.00 little change
Pied/White wagtail (Motacilla alba) 20 0.00 little change 1 0.00 little change
Pochard (Aythya ferina)t 140 0.03 strong increase 20 0.04 strong increase
Quail (Coturnix coturnix)u -70 -0.04 strong decline -55 -0.15 strong decline
Raven (Corvus corax)s 42 0.02 weak increase 6 0.01 weak increase
Red grouse (Lagopus lagopus scotica)s
11 0.00 little change -5 -0.01 little change
Red kite (Milvus milvus) 516 0.16 strong increase 84 0.13 strong increase
Shelduck (Tadorna tadorna)s 23 0.01 little change 4 0.01 little change
Shoveler (Anas clypeata) -100 0.00 Not available 52 0.09 strong increase
Stone curlew (Burhinus oedicnemus)
-25 -0.02 weak decline -20 -0.04 strong decline
Stonechat (Saxicola rubicola)s 117 0.03 strong increase 84 0.13 strong increase
Swallow (Hirundo rustica) -22 -0.01 little change -31 -0.07 strong decline
Swift (Apus apus)s -58 -0.04 strong decline -28 -0.06 strong decline
Whinchat (Saxicola rubetra)s -47 -0.03 strong decline -15 -0.03 strong decline
Woodlark (Lullula arborea)v 142 0.02 weak increase -11 -0.02 weak decline
50
p Data for the long-term assessment are from 1988 to 2018 q Data for the long-term assessment are from 2001 to 2018 r Data for the long-term assessment are from 1974 to 2018 s Data for the long-term assessment are from 1995 to 2018 t Data for the long-term assessment are from 1989 to 2018 u Data for the long-term assessment are from 1990 to 2018 v Data for the long-term assessment are from 1980 to 2018
51
Annex B Frequently asked questions Wild Bird Populations in England, 1970 to 2019
Why monitor bird populations?
Bird populations have long been considered to provide a good indication of the broad
state of wildlife in England. 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 comparisons between the short term and long term. Because they are a
well-studied taxonomic group, drivers of change for birds are better understood than
for other species groups, which enables better interpretation of any observed
changes.
Which species of birds are included in the indices?
There are 4 main habitat groups representing farmland, woodland, water and
wetland and seabird habitats. Species within each habitat type are included in the
indices if they have a population of at least 300 breeding pairs and are common
birds that are native to, and breed in England; the trends included refer to breeding
populations (except for those used in the winter waterbird indicator). There is also
an all-species indicator where all of the species included in the farmland, woodland,
wetland and seabird indicators are included here, as well as species associated with
urban habitats (e.g. collared dove, house martin), with uplands (e.g. hen harrier, red
grouse), with heathlands (e.g. Dartford warbler, hobby) and species that occupy a
range of habitats (e.g. peregrine, black-headed gull).
What are 'unsmoothed' and 'smoothed' indices and why are they used?
Two trends are referred to in the text: the unsmoothed indices show year-to-year
fluctuation in populations, reflecting the observed changes in the survey results, and
smoothed trends, which are used to formally assess the statistical significance of
change over time. Smoothed trends are used for both long and short-term
assessments as they reduce the short-term peaks and troughs resulting from, for
example, year-to-year weather and sampling variations.
What is the difference between a 'long-term' and 'short-term' trend?
There are no differences between the way the trends are calculated as they both use
the smoothed indices, it is only that in most cases the long-term trend goes back to
the earliest data point, usually 1970, whereas the short-term trend looks at the most
recent 5 years, that is year 6 to year 1.
52
Why should users not place too much reliance on short-term changes from
one year to another?
Looking at the data from year to year may include weather effect and sampling
variations which would not provide reliable data as the trend is not over a longer time
frame.
Why use indices rather than absolute numbers?
It is not possible to determine changes in the actual numbers of birds for each
species in England each year, however it is possible to estimate the relative change,
from counts on sample plots surveyed as part of a range of national monitoring
schemes.
How are the individual species indices combined into a single indicator and
why is it done?
The creation of the all species wild bird indicator involves two steps: (1) the
production of annual population indices for the individual species for which there is
trend data, and (2) the amalgamation of these individual indices into a single
aggregate index.
1. Indices for individual species: These are generated by a statistical analysis of
representative sites resurveyed year after year (e.g. in the Breeding Bird Survey) or
based on annual or periodic estimates of total populations (e.g. Heronries Survey).
The population trends for each species are made comparable by expressing them as
indices relative to ‘100’ in the start year. Thus each annual index shows relative
changes in population size from the start year: a rise to 200 in the index reflects a
doubling in numbers, a decline to 50 a halving.
2. Amalgamating into a single index: The all species index is calculated as the
geometric mean1 of all the individual indices2, with no weightings - so each species
has the same relative effect on the indicator. The geometric mean is used to ensure
that a doubling in the population index of one species (e.g. 100 to 200) is balanced
by a halving (e.g. 100 to 50). The geometric mean of 200 and 50 is 100.
The composite all species indicator shows the year-to-year fluctuations in population
trends across all species that can be included, reflecting the observed changes in
the annual survey results. Alongside this is the smoothed version of the trend, which
is used to formally assess the statistical significance of change over time. The
smoothed trend is derived using a published statistical methodology and is used for
assessments as it reduces the short-term peaks and troughs resulting from, for
example, year-to-year impacts of weather and sampling variations. The index is
53
considered to give reliable medium to long-term trends but strong reliance should not
be attached to short term changes from one year to the next.
What is the 'geometric mean', how is it calculated and why is it used?
The geometric mean is an average. It is calculated by multiplying a set of index
values and taking the nth root, where n is the number of index values. More
information can be found in Introduction to the Wild Birds Population Indicator. The
geometric mean is used to ensure that a doubling in the population index of one
species (e.g. 100 to 200) is balanced by a halving (e.g. 100 to 50). It allows for each
species to have the same relative effect on the indicator.
What does 'modelling count data' mean?
For those species covered by the Common Bird Census (CBC) and Breeding Bird
Survey (BBS), all data from survey sites are used in the generation of trends,
regardless of the habitat at these sites (e.g. survey data from woodland sites is used
in the trends for farmland species and vice versa). Trends are generated from the
two data sources using the joint-model methods described by Noble et al. (2003a).
Generalized linear models (GLMs) are used, with the application of a post-hoc
smoothing spline to produce smoothed indices for each species, thereby removing
short-term fluctuations that may be caused by sampling error, or minor fluctuations
due to weather effects, for example. Such smoothing does however mean that the
estimates for the final year of a trend must be treated with caution as they lack the
smoothing effect of data in subsequent years. The nature of smoothed trends, in that
data from any given year has an impact on trend values for earlier (and later) years
means that existing species indices (and hence indicator) values will be different in
subsequent annual revisions.
Data from the CBC and BBS are combined and analysed statistically in a single GLM
with site and year effects, as described at http://www.bto.org/about-
birds/birdtrends/2013/methods/cbcbbs-trends. Equal weight is given to CBC and
BBS sites by assigning each CBC site the mean of the BBS site weighting.
Confidence limits on these species trends are generated by bootstrapping; repeated
resampling (with replacement) to generate a sample of estimated trend values, with
the 2.5% and 97.5% percentiles giving the 95% confidence limits around the trend
value for each year.
What are 'confidence intervals' and why are they used?
The trends in this publication are based on estimates from surveys. Smoothed trends
are presented with 95% confidence intervals (CI), which are a measure of the
precision of these survey estimates. While the exact value for an indicator in a
54
particular year cannot be known, a 95% CI means users can be 95% confident that
the true value of the indicator falls within the confidence interval around it.
Why are the confidence intervals for some indices such as 'breeding generalist
farmland birds' so much wider than they are for other indices such as
'breeding generalist woodland birds' and what is it indicating?
The size of confidence intervals (CIs) varies among habitat indicators because their
width is influenced by the number of species in each indicator and the precision of
the individual species trends that make up the indicator. The precision of these
trends varies due to differences in sample size. More specifically, the CIs for
generalist farmland birds indicator is wider than the CIs for generalist woodland birds
indicator because there are only 7 individual species in the former indicator, whereas
there are 12 species in the latter. Wider confidence intervals imply that the range of
values within which users can be confident the true indicator value falls is greater
than it would be for a narrower confidence interval. Therefore, users can be 95%
confident that the true value of the breeding generalist woodland birds indicator falls
within a narrower range of values than the true value of the breeding generalist
farmland birds indicator.
Why is the percentage change used to define a 'weak increase' different to that
used to define a 'weak decline'?
Asymmetric percentage change thresholds are used to define these classes as they
refer to proportional change, where a doubling of a species index (an increase of
100%) is counterbalanced by a halving (a decrease of 50%).
What is 'bootstrapping' and why is it used?
Bootstrapping, a statistical method that estimates the uncertainty in a trend through
repeated re-sampling and trend estimation. Confidence intervals for the estimated
trends are calculated from percentiles (such as 2.5% and 97.5%) of the sample of
estimated trend lines. The procedures currently used provide a measure, and level of
confidence, of the indicator value in any particular year (e.g. 2014) relative to the
start year of the time series. It is feasible to calculate the change, and confidence in
that change, for any other time period (e.g. over five years from 2009 to 2014) but
this requires all of the constituent population trends and their bootstraps to be
recalculated using the start year (e.g. 2009) as a baseline.
Why does the overall index for breeding wild birds in England not appear to
reflect the large reductions in the population of farmland birds during the
1980s and why did the population of farmland birds suffer so much during that
time?
55
The overall ‘all-species’ index is comprised of 118 species of birds, all widespread
species with populations of at least 300 breeding pairs for which there are sufficient
data. It represents 4 habitat types (including farmland birds) and a further 31
generalist species with no particular habitat preference. Species trends within this
index vary widely, from species increasing several-fold (e.g. buzzard, Cetti’s warbler,
great spotted woodpecker, and collared dove) to those having declined to less than a
tenth of their 1970 numbers (turtle dove, tree sparrow, willow tit and grey partridge).
Within the index, 32% of the 118 species increased, 35% showed little change and
30% declined between 1970 and 2016. The apparent declines in the farmland birds
indicator (comprising of 19 species, so just 16% of the total species in the all-species
indicator) are being mitigated by increases in some of the other species in the
indicator.
The large declines in the abundance of many farmland birds have many known and
potential causes. For a large part, declines have been caused by the changes in
farming practices that have taken place since the 1950s and 60s, such as the loss of
mixed farming, a move from spring to autumn sowing of arable crops, change in
grassland management (e.g. a switch from hay to silage production), increased
pesticide and fertiliser use, and the removal of non-cropped features such as
hedgerows. The rate of these changes, which resulted in the loss of suitable nesting
and suitable feeding habitats, and a reduction in available food, was greatest during
the late 1970s and early 1980s, the period during which many farmland bird
populations declined most rapidly.
What are the main differences between 'generalist' and 'specialist' bird
populations and why have they fared so differently since the 1970s?
Specialist bird species are considered to be largely or wholly dependent on one
particular habitat whereas generalist bird species utilise a wider range of habitats.
Specialist bird species may find it difficult to adapt to changes in their habitats while
generalist bird species may find it easier to adapt because they are not as reliant on
one specific habitat type. For example, the woodland bird index is comprised of
trends for 34 species. Between 1970 and 2017, the index for woodland specialists
which are highly dependent on woodland habitats declined by 42% while the index
for woodland generalists, many of which have adapted to using gardens and wooded
areas in farmland including woodland, showed a 10% increase.
Are species of birds included in the trends if they are introduced in subsequent
years?
Yes. Species of birds which are introduced into the indices in later years will be
included and trends calculated.