Wild bird index - Gov.uk

1 downloads 131 Views 2MB Size Report
The farmland bird index contains data for 19 species. The long-term decline of farmland birds in the UK has been driven
© Crown copyright 2017 You may re-use this information (not including logos) free of charge in any format or medium, under the terms of the Open Government Licence. To view this licence, visit www.nationalarchives.gov.uk/doc/open-government-licence/ or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or e-mail: [email protected] This document/publication is also available on our website at: https://www.gov.uk/government/statistics/wild-bird-populations-in-the-uk The statistical datasets for the publication can be found here: https://www.gov.uk/government/statistical-data-sets/env07-wild-bird-populations-in-the-uk Responsible Statistician: Christine Holleran Any enquiries regarding this document/publication or the statistical datasets should be sent to us at: [email protected] or Biodiversity Statistics Team Department for Environment, Food and Rural Affairs Foss HouseKings Pool 1-2 Peasholme Green York YO1 7PX

PB 14485 All photos are copyright © Natural England https://www.flickr.com/photos/naturalengland/albums/72157627865255667/with/94989772 11/ 2

Contents Contents .............................................................................................................................. 3  UK executive summary ........................................................................................................ 4  Why monitor bird populations? ............................................................................................ 5  Understanding the bird population indices ........................................................................... 5  Assessing trends ................................................................................................................. 6  1. Native breeding wild bird populations in the UK............................................................... 8  2. Breeding farmland bird populations in the UK................................................................ 10  3. Breeding woodland bird populations in the UK .............................................................. 15  4. Breeding water and wetland bird populations in the UK................................................. 20  5. Breeding seabird populations in the UK ......................................................................... 27  6. Wintering waterbird populations in the UK ..................................................................... 29  Main notes: methodological detail, limitations of the indicators and further information ..... 32  Annex A: Trends in bird species, by habitat group, in the UK ............................................ 34  Annex B: Frequently asked questions: .............................................................................. 47 

3

UK executive summary 120 100

Index (1970=100)

The combined all-species index has changed 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

80

All species (130)

60 40 20 0 1970

1980

1990

2000

2010

Short-term trend: between 2010 and 2015…

Latest year: 2016… the unsmoothed all-species index in the UK was 7% below its 1970 value.

the smoothed all-species index was 1% lower than 2010.

the unsmoothed farmland bird index was less than half of its 1970 value; most of this decline occurred between the late 1970s and early 1980s. the unsmoothed woodland bird index was 23% less than its 1970 value.

the smoothed farmland birds index decreased by 9%. the smoothed woodland bird index declined by 2%. the smoothed water and wetland bird index declined by 2%.

the unsmoothed water and wetland bird index was 8% lower than in 1975. In 2015, the unsmoothed seabirds index was 22% below its 1986 valuea.

between 2009 and 2014, the seabird index declined by 6%. In 2013, numbers dipped to their lowest ever but they have since increased slightlya.

the unsmoothed wintering waterbirds index was 87% higher than in 1975/76, the index peaked in 1996 and has slowly declined since.

the smoothed wintering water bird index fell by 8%.

Smoothed trends at a glance Index All bird species Farmland birds Woodland birds Water and wetland birds ab

Seabirds Wintering waterbirds

-8% -56% -23% -20% 92%

Long term 1970-2015 1970-2015 1970-2015 1975-2015 1986-2014 1975/76-2014/15

-9% -6% -8%

Short term 2010-2015 2010-2015 2010-2015 2010-2015 2009-2014 2009/10-2014/15

a

the individual indicator has not been updated however an estimate has been used to calculate the all bird species index.

b

the seabirds indicator is an unsmoothed trend as no smoothed trend is available. is used to depict no significant change.

4

Why monitor bird populations? 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 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 enable 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. 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 the UK 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. Trends in bird populations are used by policy makers, government agencies and nongovernmental organisations as part of the evidence base to assess the effects 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 largely undertaken by volunteer experts, 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 2016 in populations of common birds (species with a population of at least 500 breeding pairs) that are native to, and breed in, the UK, with trends overall as well as for four 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 the UK. The charts presented combine individual species indices2 into a single indicator to provide an overall trend for each group

See ‘Main notes’ at the end for more details of the surveys sources used. 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. 1 2

5

mentioned above. 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. 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. The most recent year of data, i.e. 2016 in this update, is likely to change due to the smoothing process following the inclusion of 2017 data in next year’s update. As a result it is not appropriate to make assessments including 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 we are 95% confident that the true value of an indicator in a given year falls within the confidence interval around it. The size of the confidence intervals varies among indicators for each habitat because the width of the confidence interval is influenced by the number of species in each indicator and the precision of the individual species trends that make up the indicator. 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 five years (2010-2015).

Annex A shows long-term and short-term assessments for each individual bird species.

There are currently no smoothed trends available for seabirds. See analytical methods on BTO website (www.bto.org/birdtrends2011/methodology.htm) Fewster et al. 2000. Ecology 81: 1970-84. 3 4

6

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 the long or short-term, 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 No 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 used in the Birds of Conservation Concern5 status assessment for birds in the UK. 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) and the Joint Nature Conservation Committee (JNCC).

See the BTO website (http://www.bto.org/volunteer-surveys/birdtrack/bird-recording/birds-conservationconcern) 5

7

1. Native breeding wild bird populations in the UK In 2016, the all-species index in the UK was 7% below its 1970 value. The smoothed index showed a long-term decline of 8% over the period from 1970 to 2015. The indicator declined between the late 1970s and the late 1980s, driven mostly by relatively steep declines in woodland and farmland birds. The all-species index has since levelled off and the smoothed index shows no significant change between 2010 and 2015.

Figure 1: Populations of wild birds in the UK, 1970 to 2016

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).

8

Long term Within the index, 32% of the 130 species increased, 36% have shown no change and 29% have declined between 1970 and 2015. It was not possible to calculate a long-term trend for four species because their data series start in 2006 or later. Short term Over the short-term period between 2010 and 2015, 37% of species increased, 28% showed no change and 35% showed decline. Species breakdown The 130 species of birds included in the index includes all widespread species, with populations of at least 500 breeding pairs, for which we have sufficient data. Species trends within this index vary widely, from species increasing several-fold (e.g. Cetti's warbler, blackcap, buzzard, red-breasted merganser, great spotted woodpecker, red kite and collared dove) to those having declined to less than a tenth of 1970 numbers (turtle dove, capercaillie, corn bunting, willow tit and grey partridge). 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 in more detail in the chapters that follow. Figure 1a: Populations of wild birds in the UK by habitat, 1970 to 2016

9

2. Breeding farmland bird populations in the UK Farmland refers to the 75% of land in the UK which is devoted to agriculture. Farmland also provides seminatural habitats such as hedgerows and field margins that provide food and shelter to birds. In 2016 the UK farmland bird index was less than half its 1970 value. The majority of this decline occurred between the late 1970s and the 1980s largely due to the impact of rapid changes in farmland management during this period. More recently the smoothed index decreased 9% between 2010 and 2015.

Figure 2: Breeding farmland birds in the UK, 1970 to 2016

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).

10

Long term Since 1970, 22% of species show a weak increase, 11% show no change and 67% show either a weak or a strong decline. Short term Some species are recovering over the short-term period between 2010 and 2015, 32% of species show an increase, 42% show no change and 26% show a decline. Factors affecting farmland bird populations 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 1960s, 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. 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, for example greenfinch. Species breakdown The farmland bird index contains data for 19 species. The long-term decline of farmland birds 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’). Between 1970 and 2016, the unsmoothed index for farmland specialists declined by 70% while for farmland generalist it declined by 12%. The smoothed trend shows a decline of 70% for specialists and 13% for generalists (figure 2a).

11

Figure 2a: Breeding farmland birds in the UK, 1970 to 2016

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 Skylark of cereal crops, and increased pesticide use, have been demonstrated to have had adverse impacts on farmland birds such as skylark and grey partridge. However, species such as woodpigeon, albeit generalist, have benefitted from increased availability of their food throughout the winter. Four farmland specialists (corn bunting, grey partridge, turtle dove and tree sparrow) have experienced severe declines of 90% or more since 1970. In contrast, two other farmland specialists (stock dove and goldfinch) have more than doubled over the same period, illustrating how responses to pressures varies between species. The smoothed index show that between 2010 and 2015 specialists declined by 10%. A number of species have shown marked change in numbers over this five-year period, with turtle dove decreasing by 71%, lapwing by 17% and grey partridge by 15%, whereas stock dove, and goldfinch increased by 17% and 15% respectively. Although numbers of tree sparrow have declined in the long term, the shortterm trend shows a weak increase of 8%.

12

Figure 2b: Breeding specialist farmland birds in the UK, 1970 to 2016

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, 75% of the 12 specialist species in the farmland indicator have declined over this long-term period, while 17% increased and 8% have shown no change. Short term Between 2010 and 2015, 25% of the specialist species showed a decline, while half of the specialist species show no change and 25% show an increase.

Farmland generalists Three generalist species have declined over the long-term period, yellow wagtail by over 67%, kestrel by 50% and greenfinch by 46%. While two species (rook and reed bunting)

13

have not changed significantly overall, two species have increased; woodpigeon and jackdaw populations have more than doubled relative to 1970 levels.

Figure 2c: Breeding generalist farmland birds in the UK, 1970 to 2016

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).

Short term The smoothed index show that between 2010 and 2015 generalists declined by 6%. Two out of seven species decreased over this short-time period; kestrel by 16% and greenfinch by 40%. Greenfinch has been strongly impacted by the disease trichomonosis, which may also have affected other species such as turtle dove, in recent years. Three species have shown signs of recent improvement, most notably the yellow wagtail, which has increased by 18% following a longterm decline.

14

3. Breeding woodland bird populations in the UK Woodland covers 13% of the UK’s land area, providing trees and other vegetation suitable for nesting, foraging opportunities and cover from predators. In 2016 the UK woodland bird index was 23% below its 1970 value. The greatest decline occurred between the early 19080s and the early 1990s. The index has been more stable, at around 80% of the 1970 numbers since 1995. The smoothed index shows no significant change in the short-term, since 2010.

Figure 3: Breeding woodland birds in the UK, 1970 to 2016

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).

15

Long term Since 1970, 28% of species increased, 44% show no change and 28% declined, the majority of the latter showing a strong decline. Short term Over the short-term period between 2010 and 2015, 35% of species show an increase, 27% show no change and 38% show a decline.

Factors affecting woodland birds The declines in woodland birds have several known and potential causes, such as a lack of woodland management 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. In addition, several declining woodland birds are long-distance migrants, and a decline in the extent or quality of habitats used outside the breeding season may be one factor affecting these species outside of the UK. Positive factors would be increasing area of woodland cover and milder winters potentially having a positive impact for some species. Species breakdown The woodland bird index contains data for 37 species. The relatively flat trend for all woodland birds from the mid-1990s masks different underlying trends for: specialist species, those which are highly dependent on woodland habitats; and generalist species, which are found in a wide range of habitats, including woodland. In 2016, the woodland specialists index was 43% lower than in 1970 while for woodland generalist it was 12% higher. The smoothed trend shows a long-term decline of 41% for specialists and a 6% increase for generalists (figure 3a).

16

Figure 3a: Breeding woodland birds in the UK, 1970 to 2016

Notes: i) figures in brackets show the number of species, ii) graph shows unsmoothed trends (dashed lines) and smoothed trends (solid lines).

Woodland specialists Five woodland specialists, lesser spotted woodpecker, lesser redpoll, spotted flycatcher, capercaillie and Willow willow tit have declined by over 80% relative to 1970 tit levels, with the latter down by 93%. In contrast, populations of blackcap, and nuthatch have more than doubled over the same period and the great spotted woodpecker has more than trebled. The smoothed index shows that between 2010 and 2015 specialists decreased 3%. A number of species have shown marked trends over this five-year period, with lesser spotted woodpecker decreasing by 38% and the common crossbill by 46%, whereas spotted flycatcher has increased by 25%, blackcap has increased 21%, redstart, pied flycatcher and chiffchaff all have increased by 20% and tree pipit increased by 15%. Trends in long-distance migrants may reflect changing conditions on their wintering grounds whereas declines in residents such as lesser spotted woodpecker, willow tit and capercaillie are due to changes on their breeding grounds.

17

Figure 3b: Breeding specialist woodland birds in the UK, 1970 to 2016

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, 40% of the 20 specialist species in the woodland indicator have declined over the longterm period (1970-2015), while 30% increased and 30% show no change. Short term Between 2010 and 2015, 36% of the 25 specialist species increased, 24% show no change and 40% show a weak or strong decrease.

Woodland generalists

Great tit

The majority of generalist woodland species, many of which have adapted to using gardens and wooded areas in farmland landscapes, have not shown a substantial change over the long term and the overall woodland generalist smoothed index increased by 6% since 1970. Long term Populations of four woodland generalist species (bullfinch, song thrush, dunnock and tawny owl) have declined more than 25% since 1970; song thrush by 50%. In contrast, populations of wren, great tit and long tailed tit increased by more than 50% over the same period. 18

Figure 3c: Breeding generalist woodland birds in the UK, 1970 to 2016

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).

Short term The smoothed index for generalists show a 2% increase between 2010 and 2015. Four out of twelve species decreased over this short-term period; chaffinch by 12%, long tailed tit by 7% and great tit and blue tit by 6%. Four species increased; wren showing the strongest increase, of 31% whilst there were weaker increases for robin (12%), song thrush by 9% and bullfinch by 8% over the short-term period of 2010 to 2015.

19

4. Breeding water and wetland bird populations in the UK Water and wetlands include rivers, lakes, ponds, reedbeds, coastal marshes and lowland raised bogs, together totalling 3% of the UK’s area and providing important habitats for birds. The water and wetland bird index has remained fairly stable for most of the period since data collection started in 1975 but has been lowest in the last decade. In 2016 the water and wetland bird index was 8% lower than its value in 1975.

Figure 4: Breeding water and wetland birds in the UK, 1975 to 2016

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).

20

Long term Over the long term, 29% of species show an increase, 29% show no change and 41% show a decline, with more species exhibiting a weak rather than a strong change. Short term Over the short-term period between 2010 and 2015, 31% of species show an increase, 27% show no change and 42% show a decline. 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. Species breakdown The 26 species of bird included in the water and wetland bird index can be split into four categories for producing sub-habitat indicators. Although the index for all wetland and waterways species shows a relatively flat trend this masks underlying 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.

21

Figure 4a: Populations of water and wetland birds in the UK, 1975 to 2016

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 four 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 have Mallard shown the most positive trend, in 2016 the index was 44% higher than in 1975 (Figure 4b) although the smoothed index has shown a 7% decrease in the more recent short-term period between 2010 and 2015. Over the long term there were marked increases in two duck species, mallard and tufted duck trebling and doubling respectively. The index for coot shows an increase of 69%. However, moorhen and little grebe have declined by almost a third since 1975.

22

Figure 4b: Breeding birds of slow flowing and standing water in the UK, 1975 to 2016

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, three of the six species increased in the long term and two showed no change and in the short term one increased, three showed mainly weak declines and two showed no change. Short term In contrast to long-term increases, the smoothed indices for mallard and tufted duck showed no change over the short term. The index for coot showed a strong decline of 18% despite the longterm indicator showing a weak increase. Little grebe shows a weak 10% increase in the short term and moorhen continues to show a weak decline (10%).

Birds of fast flowing water The index for birds of fast flowing water has declined by 13% since 1975. Like the overall indicator for breeding wetland and waterways birds, it dipped from 2010-2013, although not as low as in the early eighties, and has increased in the most recent years (Figure 4c).

23

Figure 4c: Breeding birds of fast flowing water in the UK, 1975 to 2016

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 indices for grey wagtail and common sandpiper have declined; by 39% and 46% respectively, while numbers of goosander have more than doubled and the index for dipper showed no change. Short term In the short term between 2010 and 2015 goosander and grey wagtail indices increased strongly; by 19% and 15% respectively, while the dipper index showed a weak increase of 7% and the common sandpiper declined by 7%.

Birds of reedbeds The index for birds of reedbeds was 10% higher in 2016 than in 1975 (Figure 4d). The smoothed index has shown no significant change since 2010.

Sedge warbler

24

Figure 4d: Breeding birds of reedbeds in the UK, 1975 to 2016

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, sedge warbler and reed bunting have shown declines, of 42% and 63% respectively. In contrast Cetti’s warbler has shown a six-fold increase since 1988 (when data collection started) and there has been an 83% increase in reed warblers since 1981. Short term During the short term period, sedge warblers declined strongly, falling 24% between 2010 and 2015, whilst declines in reed bunting remain weak. Cetti’s warbler increased strongly, by 44% and reed warbler showed no change since 2010.

Birds of wet grassland The unsmoothed index for birds of wet grassland has decreased by 51% since 1975 (Figure 4e). The majority of the decline occurred between the peak in the mid-1980s and the mid-1990s. More recently the indicator has fallen less steeply, the smoothed indicator shows little change over the period 2010 to 2015. 25

Figure 4e: Populations of wet grassland birds in the UK, 1975 to 2016

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 wildfowl (mute swan and teal) have shown an increase, yellow wagtail and waders such as snipe have declined by 97% and 81% respectively. Short term Over the short term since 2010, yellow wagtail continues to decline strongly by 53% along waterways and lapwing numbers have fallen by 11%. In contrast the index for snipe has shown a weak 8% increase over this five-year period. Little egret, which was included for the first time in 2006 and therefore not assessed over the long term period, increased by 33% since 2010.

26

5. Breeding seabird populations in the UK In 2016, the Seabird Monitoring Programme Steering Group made the decision to put the analysis and publication of the annual SMP report on hold for two years. The reason for this was to enable staff time to be dedicated to the breeding seabird census, Seabirds Count. Although data is still being collected, and in higher volumes for the census, the absence of analysed data for 2016 means this indicator has not been updated. However, changes to 2016 were estimated for seabird species included in the all species index. The UK coast is over 30,000km long, and consists of a wide variety of habitats such as sea cliffs, sand dunes, shingle ridges, machair and intertidal areas. Additionally, the area of sea around the UK amounts to three and a half times the land area of the UK (not including overseas territories). In 2015, the breeding seabird index in the UK was 22% lower than in 1986, above the lowest level ever recorded in 2013 (of 27% lower than 1986). Despite fluctuations the indicator was largely flat from 1986 until the mid-2000s when seabird numbers started to decline, falling 6% between 2009 and 2014.

Figure 5: Populations of seabirds in the UK, 1986 to 2015

Note: i) figures in brackets show the number of species. ii) graph shows unsmoothed trend (solid line) - no smoothed trend is available for seabird.

27

Long term Since 1986, 23% of 13 seabird species show a weak increase, 46% show no change and 31% show either a weak or a strong decline. Short term Over the short-term period between 2009 and 2014, 38% of species show a strong increase, 8% show no change and 54% show a decline.

Species breakdown Three of the 13 seabird species in the index have Black-legged increased since the beginning of the index in 1986, kittiwake razorbill and common guillemot by over 55% and Arctic tern by 39%. Two species have declined strongly, Arctic skua by 80% and black-legged kittiwake by 62%. Declines of black-legged kittiwakes, which are surface feeders, have been linked to increases in sea surface temperatures. However, there has been some lessening of the rate of decline in the short term, showing a weak rather than strong decline of 13% between since 2009 and 2014. 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 undergone local recoveries as a result. Herring gull and great black-backed gull have increased by 47% and 28% respectively over the short term, although the trends for these species show no change over the longterm. However, Arctic skua numbers continue to decline strongly. The seabird index in the UK in 2015 continues to exhibit a different pattern to the England index6. 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. In addition, trends for some species may differ between the two countries.

The England seabird trend can be seen in the Defra National Statistics Release, Wild bird populations in England, 1970-2016, also published today. 6

28

6. Wintering waterbird populations in the UK Waterbird is used to describe all birds that inhabit or depend on water, this chapter is about waterbirds that over-winter in the UK, some of which also breed here7. In the winter of 2015/16 the wintering waterbird index was 87% higher than in 1975/76. The index peaked in the late 1990s, and has largely declined since, with the smoothed index falling 8% in the short term between 2009/10 and 2014/15. Figure 6: Wintering water birds in the UK, 1975/76 to 2015/16

Notes: i) figures in brackets show the number of species, ii) graph shows unsmoothed trend (dashed line) and smoothed trend (solid line). 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. iii) the number of species in each sub indicator do not sum to the number in the all species indicator because four 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 three different taxonomic groups none large enough to warrant a separate indicator. They are included in the all wintering waterbird indicator because they behave similarly to wildfowl and are counted in the same way, using the Wetland Bird Survey.

Not all of the wintering waterbirds in this chapter are included in the all breeding birds index, only those which also breed in the UK. In Annex A, those species that overlap are included under both.

7

29

Long term Since 1975/76, half of the 46 species in the indicator increased, 37% showed no change and 13% declined, most of the latter showing a weak decline. Short term Over the short-term period between the winters of 2009/10 and 2014/15, the percentage of species that showed an increase was 24%, while 26% showed no change, and 50% showed a decline.

Factors affecting wintering wetland bird populations Populations of wintering wetland birds are affected by a range of factors including conditions in the countries where they breed, the condition and amount of coastal and wetland habitat in the UK and changes in migratory patterns, at least some of which are known to have been affected by climatic changes. Species breakdown There are 46 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 more than doubled (109% increase) and the wader index has increased 57% since 1975/76. However, both peaked in the late 1990s and have declined since; between 2009/10 and 2014/15, the smoothed indices for both wildfowl and waders have declined by 10% and 4% respectively.

30

Wildfowl Amongst wildfowl, the Bewick’s swan has declined by 85% since the 1975/76 baseline and continues to decline strongly in the short term. The indices for the European whitefronted goose, scaup and pochard have all halved. Overall, a large number of species in the indicator show strong declines in the short term, despite showing only weak declines or no change over the long term. One goose population, the Svalbard light-bellied brent goose, shows an almost 6 fold increase in the long term but shows a strong decline (39%) in the short term. The British/Irish greylag goose and gadwall both show increases, of 36 and 12 fold, respectively, since 1975/76, and while the index for gadwall shows no change in the short term, British/Irish greylag goose shows a 17% increase in the short term.

Waders Amongst waders, the indices for avocet and black-tailed godwit have increased over 7-fold (avocet was only included in the indicator since 1989/90). Avocet The shortterm trend for the avocet is a weak 10% increase and for blacktailed godwit, a strong 25% increase. In contrast, the indices for ringed plover and dunlin showed the steepest declines, declining by 40% and 50% respectively since the winter of 1975/76. Turnstone numbers have shown no change over the long term and declined strongly, by 15%, since 2009/10.

31

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), 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 2016), 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 2013), the BTO/RSPB/JNCC Wetland Bird Survey counts (from 1975-76 to 2015-16), the WWT Goose & Swan Monitoring Programme in partnership with the JNCC and Scottish Natural Heritage, the Seabird Monitoring Programme (from 1986 to 2015), 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.

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, 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 UK, excluding rare (less than 500 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. 32

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. The underlying unsmoothed figures for the UK can be downloaded from the Gov.uk website. 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 Welsh Government Scottish Government Department for Agriculture and Rural Development, Northern Ireland

33

Annex A: Trends in bird species, by habitat8 group, in the UK 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. Farmland (19) Generalists (7)

Species Greenfinch (Chloris chloris) Jackdaw (Corvus monedula) Kestrel (Falco tinnunculus) Reed bunting (Emberiza schoeniclus) Rook (Corvus frugilegus) Woodpigeon (Columba palumbus) Yellow wagtail (Motacilla flava)

Long-term change (1970-2015) Annual Long-term Trend percentage percentage change change -46 -1.37 weak decline 148 2.04 weak increase -50 -1.54 weak decline -30

-0.80

no change

7 122 -68

0.17 1.79 -2.47

no change weak increase weak decline

Short-term change (2010-2015) Annual Short-term Trend percentage percentage change change -40 -9.84 strong decline 9 1.70 weak increase -16 -3.32 strong decline 8

1.58

weak increase

-5 -4 18

-1.09 -0.79 3.30

no change no change strong increase

8

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: 1988-1991. London: T. & A.D. Poyser.

34

Specialists (12)

Species Corn bunting (Emberiza calandra) Goldfinch (Carduelis carduelis) Grey partridge (Perdix perdix) Lapwing (Vanellus vanellus) Linnet (Carduelis cannabina) Skylark (Alauda arvensis) Starling (Sturnus vulgaris) Stock dove (Columba oenas) Tree sparrow (Passer montanus) Turtle dove (Streptopelia turtur) Whitethroat (Sylvia communis) Yellowhammer (Emberiza citrinella)

Long-term change (1970-2015) Long-term Annual percentage percentage Trend change change -90 -4.89 strong decline 159 2.14 weak increase -92 -5.42 strong decline -64 -2.23 weak decline -55 -1.77 weak decline -59 -1.96 weak decline -81 -3.63 strong decline 113 1.70 weak increase -90 -4.99 strong decline -98 -8.33 strong decline -6 -0.14 no change -56

-1.79

weak decline

Short-term change (2010-2015) Short-term Annual percentage percentage Trend change change 4 0.75 no change 15 2.81 strong increase -15 -3.23 strong decline -17 -3.68 strong decline 2 0.42 no change -5 -0.96 no change -5 -0.94 no change 17 3.24 strong increase 8 1.62 weak increase -71 -21.94 strong decline -3 -0.60 no change -2

-0.43

no change

35

Woodland (37) Generalists (12) Long-term change (1970-2015) Species Blackbird (Turdus merula) Blue tit (Cyanistes caeruleus) Bullfinch (Pyrrhula pyrrhula) Chaffinch (Fringilla coelebs) Dunnock (Prunella modularis) Great tit (Parus major) Lesser whitethroat (Sylvia curruca) Long-tailed tit (Aegithalos caudatus) Robin (Erithacus rubecula) Song thrush (Turdus philomelos) Tawny owl (Strix aluco) Wren (Troglodytes troglodytes)

Long-term percentage change

Annual percentage change

Trend no change no change no change no change no change weak increase

Short-term change (2010-2015) Short-term percentage change

Annual percentage change

-1 -6 8 -12 1 -6

-0.13 -1.15 1.51 -2.58 0.18 -1.31

3

0.55

Trend

-16 21 -39 21 -29 80

-0.38 0.42 -1.08 0.42 -0.77 1.32

no change weak decline weak increase weak decline no change weak decline

23

0.45

no change

97

1.52

weak increase

-7

-1.47

weak decline

55 -50 -37 67

0.99 -1.53 -1.01 1.15

no change weak decline no change weak increase

12 9 -5 31

2.36 1.68 -1.03 5.48

weak increase weak increase no change strong increase

no change

Specialists (25) Long-term change (1970-2015) Species Blackcap (Sylvia atricapilla) Chiffchaff (Phylloscopus collybita)

Long-term percentage change 288 105

Annual percentage change 3.06 1.61

Trend strong increase weak increase

Short-term change (2010-2015) Short-term percentage change

Annual percentage change

21 20

3.92 3.65

Trend strong increase strong increase 36

Coal tit (Periparus ater) Garden warbler (Sylvia borin) Goldcrest (Regulus regulus) Great spotted woodpecker (Dendrocopos major) Green woodpecker (Picus viridis) Jay (Garrulus glandarius) Lesser spotted woodpecker (Dendrocopos minor) Marsh tit (Poecile palustris) Nightingale (Luscinia megarhynchos)a Nuthatch (Sitta europaea) Lesser redpoll (Carduelis cabaret) Redstart (Phoenicurus phoenicurus) Sparrowhawk (Accipiter nisus) Spotted flycatcher (Muscicapa striata) Tree pipit (Anthus trivialis) Treecreeper (Certhia familiaris) Willow tit (Poecile montana) Willow warbler (Phylloscopus trochilus) Pied flycatcher (Ficedula hypoleuca)a Wood warbler (Phylloscopus sibilatrix)a Common crossbill (Loxia curvirostra)a Siskin (Carduelis spinus)a Capercaillie (Tetrao urogallus) a

15 -10 -15

0.31 -0.24 -0.36

350

3.40

100 9

no change no change no change

-16 -15 18

-3.36 -3.19 3.33

strong decline strong decline strong increase

strong increase

-5

-0.94

no change

1.56 0.18

weak increase no change

-6 2

-1.31 0.31

weak decline no change

-83

-3.82

strong decline

-38

-9.00

strong decline

-75

-3.06

strong decline

-22

-4.85

strong decline

-48

-3.24

strong decline

2

0.47

no change

250 -87

2.82 -4.42

strong increase strong decline

5 -4

1.00 -0.73

no change no change

66

1.13

no change

20

3.72

83

1.35

weak increase

-11

-2.21

-85

-4.10

strong decline

25

4.63

strong increase

-69 -10 -93

-2.59 -0.25 -5.83

weak decline no change strong decline

15 8 -10

2.83 1.57 -2.03

strong increase weak increase weak decline

-44

-1.27

weak decline

-13

-2.68

weak decline

-40

-2.50

weak decline

20

3.70

strong increase

-56

-4.08

strong decline

11

2.16

weak increase

-15

-0.83

no change

-46

-11.74

strong decline

54 -89

2.18 -4.88

weak increase strong decline

-5 -10

-0.99 -2.17

no change weak decline

strong increase weak decline

Data for the long-term assessment are from 1995 to 2015 37

Water and wetland birds (26) Birds of fast flowing water (4)  

Long-term change (1975-2015)

Species Common sandpiper (Actitis hypoleucos) Dipper (Cinclus cinclus) Goosander (Mergus merganser)b Grey wagtail (Motacilla cinerea) b

Long-term percentage change

Annual percentage change

-46

-1.55

-22 122 -39

-0.63 2.38 -1.22

Short-term change (2009-2015) Short-term percentage change

Annual percentage change

weak decline

-7

-1.47

no change

7 19 15

1.37 3.55 2.88

Trend

weak increase weak decline

Trend weak decline weak increase strong increase strong increase

Data for the long-term assessment are from 1981 to 2015

Birds of reedbeds (4) Long-term change (1975-2015) Species Cetti's warbler (Cettia cetti)c Reed bunting (Emberiza schoeniclus) Reed warbler (Acrocephalus scirpaceus)d Sedge warbler (Acrocephalus schoenobaenus) c d

Long-term percentage change

Annual percentage change

632

7.96

-63

-2.47

83

1.80

-42

-1.36

Short-term change (2010-2015) Short-term percentage change

Annual percentage change

strong increase

44

7.57

weak decline

-8

-1.57

weak decline

weak increase

-3

-0.68

no change

-24

-5.30

strong decline

Trend

weak decline

Trend strong increase

Data for the long-term assessment are from 1989 to 2015 Data for the long-term assessment are from 1981 to 2015 38

Birds of slow and standing water (6) Long-term change (1975-2015) Species Coot (Fulica atra) Great crested grebe (Podiceps cristatus)e Little grebe (Tachybaptus ruficollis) Mallard (Anas platyrhynchos) Moorhen (Gallinula chloropus) Tufted duck (Aythya fuligula) e

Long-term percentage change

Annual percentage change

Short-term change (2010-2015) Short-term percentage change

Annual percentage change

weak increase

-18

-3.88

strong decline weak decline

Trend

Trend

69

1.32

-8

-0.39

no change

-11

-2.22

-27

-0.80

no change

10

1.87

213

2.89

strong increase

-4

-0.92

no change

-30

-0.87

-10

-2.12

weak decline

99

1.73

-4

-0.87

no change

no change weak increase

weak increase

Data for the long-term assessment are from 1995 to 2015

Birds of Wet Grassland (8)

Species Curlew (Numenius arquata)f Lapwing (Vanellus vanellus)f Little egret (Egretta garzetta) Mute swan (Cygnus olor) Redshank (Tringa totanus) Snipe (Gallinago gallinago) Teal (Anas crecca)g Yellow wagtail (Motacilla flava)

Long-term change (1975-2015) Long-term Annual percentage percentage Trend change change -19 -0.62 no change -52 -2.06 weak decline N/A N/A N/A 86 1.56 weak increase -55 -1.95 weak decline -81 -4.07 strong decline 75 2.84 strong increase -97 -8.74 strong decline

Short-term change (2010-2015) Short-term Annual percentage percentage Trend change change -3 -0.62 no change -11 -2.23 weak decline 33 5.90 strong increase -3 -0.67 no change 5 1.05 no change 8 1.61 weak increase 45 7.77 strong increase -53 -14.08 strong decline 39

f g

Data for the long-term assessment are from 1980 to 2015 Data for the long-term assessment are from 1995 to 2015

Other (4)    

Long-term change (1975-2015)

Species Grey heron (Ardea cinerea) Kingfisher (Alcedo atthis) Oystercatcher (Haematopus ostralegus) Sand martin (Riparia riparia)h h

Long-term percentage change

Annual percentage change

Trend

-17 -19

1.27 0.18

no change no change

66

0.00

weak increase

7

0.00

no change

Short-term change (2010-2015) Short-term percentage change

Annual percentage change

-10 -3

-1.80 -2.17

weak decline no change

-9

0.00

weak decline

-10

0.00

weak decline

Trend

Data for the long-term assessment are from 1978 to 2015

40

Seabirds (13)

Species Arctic skua (Stercorarius parasiticus) Black-legged kittiwake (Rissa tridactyla) Common guillemot (Uria aalge) European shag (Phalacrocorax artistotelis) Great black-backed gull (Larus marinus) Great cormorant (Phalacrocorax carbo) Herring gull (Larus argentatus) Northern fulmar (Fulmarus glacialis) Common tern (Sterna hirundo) Sandwich tern (Sterna sandvicensis) Little tern (Sternula albifrons) Arctic tern (Sterna paradisaea) Razorbill (Alca torda)

Long-term change (1986-2014) Long-term Annual percentage percentage Trend change change

Short-term change (2009-2014) Short-term Annual percentage percentage Trend change change

-80

-5.58

strong decline

-56

-15.16

strong decline

-62

-3.37

strong decline

-13

-2.66

weak decline

57

1.61

weak increase

17

3.15

-48

-2.31

-20

-4.39

7

0.24

no change

28

5.07

-7

-0.26

no change

-9

-1.78

-16

-0.62

no change

47

7.96

-22

-0.90

no change

-12

-2.54

weak decline

-30

-1.27

weak decline

-24

-5.28

strong decline

5

0.16

no change

-18

-3.96

strong decline

-12 39 58

-0.46 1.17 1.64

4 15 15

0.75 2.88 2.82

no change strong increase strong increase

weak decline

no change weak increase weak increase

strong increase strong decline strong increase weak decline strong increase

41

Wintering waterbirds (46) Wildfowl (27)

Species Mute swan (Cygnus olor) Bewick's swan (Cygnus columbianus) Whooper Swan (Cygnus cygnus) Pink-footed goose (Anser brachyrhynchus) White-fronted goose, European (Anser albifrons albifrons) White-fronted Goose, Greenland (Anser albifrons flavirostris)i Greylag goose, Icelandic (Anser anser) Greylag goose, British/Irish (Anser anser anser) Barnacle goose, Greenland population (Branta leucopsis)j Barnacle goose, Svalbard population (Branta leucopsis) Brent goose, dark-bellied (Branta bernicla bernicla) Brent goose, Nearctic light-bellied (Branta bernicla)k Brent goose, Svalbard light-bellied (Branta bernicla hrota) Shelduck (Tadorna tadorna) Wigeon (Anas penelope) Gadwall (Anas strepera)

Long-term change (1975/76-2014/15) Long-term Annual percentage percentage Trend change change 171 2.58 weak increase -85

-4.72

289

3.55

444

4.44

-56

-2.09

17

Short-term change (2009/10-2014/15) Short-term Annual percentage percentage Trend change change -9 -1.81 weak decline -70

-21.64

strong increase

0

-0.02

strong increase

26

4.77

weak decline

-38

-8.99

strong decline

0.51

no change

-23

-5.14

strong decline

40

0.87

no change

-6

-1.19

weak decline

3647

9.74

strong increase

17

3.14

strong increase

175

4.13

strong increase

39

6.74

strong increase

526

4.82

strong increase

16

3.05

strong increase

205

2.90

strong increase

35

6.19

strong increase

89

2.48

weak increase

1

0.16

no change

584

5.05

strong increase

-39

-9.29

strong decline

30 136 1295

0.67 2.23 6.99

no change weak increase strong increase

-20 0 -4

-4.29 -0.07 -0.88

strong decline no change no change

strong decline

strong decline no change strong increase

42

Teal (Anas crecca) Mallard (Anas platyrhynchos) Pintail (Anas acuta) Shoveler (Anas clypeata) Pochard (Aythya ferina) Tufted duck (Aythya fuligula) Scaup (Aythya marila) Eider, except Shetland (Somateria mollissima)l Goldeneye (Bucephala clangula) Red-breasted merganser (Mergus serrator) Goosander (Mergus merganser)

179 -20 -17 106 -53 61 -50

2.66 -0.57 -0.48 1.87 -1.90 1.23 -1.78

13 -9 -17 8 -28 4 -36

2.39 -1.83 -3.76 1.61 -6.30 0.83 -8.65

weak increase weak decline strong decline weak increase strong decline no change strong decline

16

0.56

no change

-4

-0.76

no change

11

0.26

no change

-17

-3.55

strong decline

77

1.47

weak increase

-9

-1.79

weak decline

55

1.13

no change

4

0.73

weak increase no change no change weak increase weak decline weak increase weak decline

no change

i

Data for the long-term assessment are from 1982/83 to 2014/15 Data for the long-term assessment are from 1988/89 to 2014/15 k Data for the long-term assessment are from 1987/88 to 2014/15 l Data for the long-term assessment are from 1986/87 to 2014/15 j

Wader (15)

Species Oystercatcher (Haematopus ostralegus) Avocet (Recurvirostra avosetta) m Ringed plover (Charadrius hiaticula) Golden plover (Pluvialis apricaria) Grey plover (Pluvialis squatarola) Lapwing (Vanellus vanellus) Knot (Calidris canutus)

Long-term change (1975/76-2014/15) Annual Long-term Trend percentage percentage change change 2

0.05

no change

703

8.69

strong increase

-40

-1.31

183 123 81 1

2.70 2.07 1.53 0.04

Short-term change (2009/10-2014/15) Annual Short-term Trend percentage percentage change change -10

-2.19

10

1.99

weak increase

weak decline

-22

-4.78

strong decline

weak increase weak increase weak increase no change

21 -19 4 -10

3.81 -4.17 0.85 -2.00

strong increase strong decline no change weak decline

weak decline

43

Sanderline (Calidris alba) Purple sandpiper (Calidris maritima) Dunlin (Calidris alpina) Black-tailed godwit (Limosa limosa) Bar-tailed godwit (Limosa lapponica) Curlew (Numenius arquata) Redshank (Tringa totanus) Turnstone (Arenaria interpres) m Data

62

1.25

weak increase

-7

-1.36

weak decline

16

0.38

no change

-14

-2.89

strong decline

-50

-1.77

weak decline

-2

-0.45

no change

739

5.61

strong increase

25

4.50

strong increase

1

0.03

no change

3

0.56

no change

22 -1 -3

0.51 -0.03 -0.08

no change no change no change

-3 -3 -15

-0.64 -0.53 -3.18

no change no change strong decline

for the long-term assessment are from 1988/89 to 2014/15

Other (4)

Species Coot (Fulica atra)n Cormorant (Phalacrocorax carbo)o Great crested grebe (Podiceps cristatus)n Little grebe (Tachybaptus ruficollis)p n o p

Long-term change (1975/76-2014/15) Annual Long-term Trend percentage percentage change change 6 0.21 no change 65 1.95 weak increase 36

1.06

no change

98

2.77

weak increase

Short-term change (2009/10-2014/15) Annual Short-term Trend percentage percentage change change -17 -3.65 strong decline 10 2.00 weak increase -12

-2.48

weak decline

-6

-1.14

weak decline

Data for the long-term assessment are from 1984/85 to 2014/15 Data for the long-term assessment are from 1987/88 to 2014/15 Data for the long-term assessment are from 1988/89 to 2014/15

44

Other birds included in the all species index (38) The all-species line is comprised of all 130 available population trends for widespread breeding species in the UK, from all landscape types. It excludes rare species (with less than 500 breeding pairs) and all species for which no UK trend information is available. The species composition of all species index (130 species) includes: • 19 farmland* species trends (i.e. those in the farmland bird index); • 37 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); • 13 seabirds, and; • 38 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 UK and are included in the all species index. * Note that trends for three species (yellow wagtail, reed bunting and lapwing) are included in two 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 three species in the all-species indicator to avoid duplication.

Species Avocet (Recurvirostra avosetta) Bearded tit (Panurus biarmicus) Black-headed gull (Chroicocephalus ridibundus) Buzzard (Buteo buteo) Carrion crow (Corvus corone) Cirl bunting (Emberiza cirlus) Collared dove (Streptopelia decaocto) Corncrake (Crex crex) Cuckoo (Cuculus canorus) Dartford warbler (Sylvia undata)

Long-term change (1970-2015) Annual Long-term percentage Trend percentage change change 320 5.91 strong increase 10 0.26 no change

Short-term change (2010-2015) Annual Short-term Trend percentage percentage change change 12 2.35 weak increase 10 1.99 weak increase

16

0.34

no change

-6

-1.23

465 98 79

3.92 1.53 4.23

strong increase weak increase strong increase

5 3 17

0.89 0.52 3.26

no change no change strong increase

799

5.00

strong increase

-15

-3.12

strong decline

-55 -57 285

-1.76 -1.83 3.43

weak decline weak decline strong increase

-8 15 122

-1.68 2.92 17.33

weak decline strong increase strong increase

weak decline

45

Firecrest (Regulus ignicapilla) Gadwall (Anas strepera) Golden plover (Pluvialis apricaria) Greylag goose (Anser anser) Hen harrier (Circus cyaneus) Hobby (Falco subbuteo) Hooded crow (Corvus cornix) House martin (Delichon urbicum) House sparrow (Passer domesticus) Magpie (Pica pica) Meadow pipit (Anthus pratensis) Mediterranean gull (Larus melanocephalus) Mistle thrush (Turdus viscivorus) Peregrine (Falco peregrinus) Pied/White wagtail (Motacilla alba) Pochard (Aythya ferina) Quail (Coturnix coturnix) Raven (Corvus corax) Red grouse (Lagopus lagopus scotica) Red kite (Milvus milvus) Red-breasted merganser (Mergus serrator) Shelduck (Tadorna tadorna) Shoveler (Anas clypeata) Stonechat (Saxicola rubicola) Swallow (Hirundo rustica) Swift (Apus apus) Whinchat (Saxicola rubetra) Woodlark (Lullula arborea)

N/A 126 -20 298 -2 -11 17 -11

N/A 4.17 -1.12 6.48 -0.08 -0.60 0.80 -0.57

N/A strong increase no change strong increase no change no change no change no change

93 32 -6 9 -15 -21 12 -7

14.01 5.66 -1.28 1.73 -3.19 -4.70 2.21 -1.53

strong increase strong increase weak decline weak increase strong decline strong decline weak increase weak decline

-72

-2.81

strong decline

-3

-0.66

no change

97 -34

1.52 -0.91

weak increase no change

1 19

0.10 3.60

no change strong increase

N/A

N/A

N/A

-15

-3.28

strong decline

-55 203 38 44 -39 38

-1.76 2.49 0.72 1.67 -1.97 1.64

weak decline weak increase no change weak increase weak decline weak increase

2 2 13 7 -63 10

0.48 0.44 2.46 1.45 -18.21 1.93

no change no change weak increase weak increase strong decline weak increase

14

0.65

no change

15

2.90

strong increase

349

14.63

strong increase

85

13.04

strong increase

500

4.06

strong increase

-18

-3.86

strong decline

-8 N/A 50 8 -51 -52 126

-0.40 N/A 2.04 0.17 -3.47 -3.58 3.78

no change N/A weak increase no change strong decline strong decline strong increase

-2 -3 -1 -13 -24 8 62

-0.45 -0.64 -0.27 -2.82 -5.39 1.47 10.11

no change no change no change strong decline strong decline weak increase strong increase

46

Annex B: Frequently asked questions: Wild Bird Populations in the UK, 1970 – 2016 Why do we monitor bird populations? 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 comparisons between the short term and long term. Because they are a wellstudied 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 500 breeding pairs and are common birds that are native to, and breed in the UK. 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 1970 whereas the short-term trend looks at the most recent 5 years. Why should we 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. A trend can only be established where there are at least 3 data points, or more specifically in this publication, at least 3 years of data. Why do we use indices rather than absolute numbers? 47

It is not possible to determine changes in the actual numbers of birds for each species in the UK 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 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 (baseline) 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 mean of all the individual indices, 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-toyear impacts of weather and sampling variations. The index is 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? 48

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/aboutbirds/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 we cannot know the exact value for an indicator in a particular year, a 95% CI means we are 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 we are confident the true indicator value falls is greater than it would be for a narrower confidence interval. Therefore, we are 95% confident that the true value of 49

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 the UK 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? The overall ‘all-species’ index is comprised of 130 species of birds, all widespread species with populations of at least 500 breeding pairs for which there are sufficient data. It represents 4 habitat types (including farmland birds) and a further 38 generalist species with no particular habitat preference. Species trends within this index vary widely, from species increasing several-fold (e.g. Cetti's warbler, blackcap, buzzard, red-breasted merganser, great spotted woodpecker, red kite and collared dove) to those having declined to less than a tenth of 1970 numbers (turtle dove, capercaillie, corn bunting, willow tit and grey partridge). Within the index, 32% of the 130 species increased, 36% showed no change and 29% declined between 1970 and 2015. The apparent declines in the farmland birds indicator (comprising of 19 species) 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

50

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 37 species. Between 1970 and 2016, the index for woodland specialists which are highly dependent on woodland habitats declined by 43% while the index for woodland generalists, many of which have adapted to using gardens and wooded areas in farmland including woodland, showed a 12% increase.

51