speciesaccounts_bewicksswanBewick’s Swan

Cygnus columbianus bewickii

The Northwest European population of Bewick’s Swan winters mainly in Britain, the Netherlands and Germany, with smaller numbers in Denmark, Sweden, Belgium and France. The population breeds at high latitudes in Arctic Russia from the Fenno-Russian border east to the Lena Delta.

There are also two other populations of Bewick’s Swan: an eastern population which breeds in Arctic Russia to the east of the Lena Delta and winters in Japan, China and Korea; and a much smaller population that winters in the Caspian Sea region.

The Northwest European population is a conservation priority, having declined by more than a quarter since the mid 1990s. An AEWA Single Species Action Action Plan was published in 2012 to focus and coordinate conservation efforts.

  • Conservation Status

    Global status (IUCN Red List of Threatened Species)

    African-Eurasian Waterbird Agreement (AEWA)

    European status (European Red List of Birds)

    The Birds Directive (European Commission)

    UK status (Birds of Conservation Concern)

    UK quarry species (Wildlife & Countryside Act 1981)

    * assessed at species level Tundra Swan Cygnus columbianus

    Least Concern*

    A2; International Single Species Action Plan

    Endangered (Europe and EU27)*

    Annex I

    Amber

    not huntable

    Population Status

    Flyway population size (Wetlands International 2015)

    GB estimate (Musgrove et al. 2011)

    Irish estimate (Crowe & Holt. 2013)

    GB trend (SUKB 2014)

    Breeding success (GSMP survey)

    18,000 – 18,100 individuals

    7,000 individuals

    150 individuals

    Long-term trend (1985/86 – 2011/12) = 47% decrease
    Ten-year trend (2001/02 – 2011/12) = 35% decrease

    Varies markedly between years and sites, generally 5-25%

    Summary statistics

    The number of Bewick’s Swans recorded in Britain and Ireland during the International Swan Census, 1984-2010, and the estimate of the size of the Northwest European population (Beekman pers comm; Rees & Beekman 2010).

    Census year Number of swans in Britain & Ireland Estimate of NW European population size
    2010 7,079 18,000
    2005 7,216 21,500
    2000 7,597 23,500
    1995 7,563 29,277
    1990 10,758 25,838
    1987 9,166 16,046
    1984 6,239 16,283

    Annual estimates of the percentage of young and mean brood size (young per successful pair) of Bewick’s Swan in Britain (recorded at WWT Welney, the Ouse Washes, Nene Washes, WWT Martin Mere, Ribble Estuary and WWT Slimbridge, where age assessments are made annually), 2003/04 – 2015/16.

    Season Percentage of young (%) Mean brood size
    2015/16 13.5 1.7
    2014/15 9.7 1.5
    2013/14 14.7 2.1
    2012/13 16.9 1.7
    2011/12 11.5 1.8
    2010/11 10.8 1.7
    2009/10 9.1 1.5
    2008/09 6.4 1.5
    2007/08 4.7 1.4
    2006/07 10.3 1.9
    2005/06 10.9 2.2
    2004/05 9.2 2.0
    2003/04 15.1 2.1

     

    References

    Crowe, O. & C. Holt. 2013. Estimates of waterbird numbers wintering in Ireland, 2006/07-2010/11. Irish Birds 9: 545-552

    Musgrove, A.J., G.E. Austin, R.D. Hearn, C.A. Holt, D.A. Stroud & S.R. Wotton. 2011. Overwinter population estimates of British waterbirds. British Birds 104: 364-397.

    Rees, E.C. & J.H. Beekman. 2010. Northwest European Bewick’s Swan: a population in decline. British Birds 103: 640-650.

     

  • Northwest European Bewick’s Swans breed at high latitudes in Arctic Russia from the Fenno-Russian border east to the Lena Delta. Birds migrate through the Baltic States to winter primarily in the Netherlands and Britain, with smaller numbers regularly occurring in Germany, Denmark, Belgium and France (Beekman et al. 1985, Rees et al. 1997). Ireland used to also support wintering Bewick’s Swans, but they occur infrequently nowadays as a results of a eastwards shift in winter distribution.

    flyway map bewicks revised_2014

    Flyway of the Northwest European Bewick’s Swan

    The winter distribution of Bewick’s Swan in Britain is highly localised. It has a southerly distribution with the largest flocks in eastern England, especially at the Nene and Ouse Washes. Smaller flocks occur in western England, and relatively small numbers in Wales.

    In Britain, Bewick’s Swans winter on shallow freshwater lakes, marshes or slow-moving rivers, near or adjacent to extensive grasslands liable to flooding. Since the early 1970s, they have taken to foraging on agricultural land, especially on waste root crops, grain stubbles and winter cereals. This switch in diet may be attributed to changes in natural habitat quality imposed by land drainage and land claim and to more extensive planting of arable crops influencing feeding site selection by the birds. Generally, Bewick’s Swans in Britain and Ireland switch from arable foods to natural grasses through the winter. Proportionately, however, arable foods remain the most important over the whole winter period. The increased use of agricultural areas in southeast England may result in some conflict with agricultural interests, particularly on re-seeded grasslands and winter cereals.

    Although this population is protected throughout its range, illegal shooting remains a threat, with 23% of live Bewick’s Swans x-rayed since 2000 found with shotgun pellets embedded in their body tissue (Newth et al. 2011). Shooting has also accounted for the death of 17.3% of dead Bewick’s Swans recovered along their migration route since the 1970s (Newth et al. 2011), and such activity is known to have occurred in the UK (Evans et al. 1973, Brown et al. 1992, Rees & Bowler 2002, Newth et al. 2011). This indicates that illegal shooting remains an issue for Bewick’s Swans, and needs to be addressed at both national and international levels.

    References

    Beekman, J.H., S. Dirksen & T.H. Slagboom. 1985. Population size and breeding success of Bewick’s Swans wintering in Europe in 1983-4. Wildfowl 36: 5-12.

    Brown, M.J., E. Linton & E.C. Rees. 1992. Causes of mortality among wild swans in Britain. Wildfowl 43: 70-79.

    Evans, M.E., N.A. Wood & J. Kear. 1973. Lead shot in Bewick’s Swans. Wildfowl 24: 56-60.

    Newth, J.L., M.J. Brown & E.C. Rees. 2011. Incidence of embedded shotgun pellets in Bewick’s swans Cygnus columbianus bewickii and whooper swans Cygnus cygnus wintering in the UK. Biological Conservation 144: 1630-1637.

    Rees, E.C. & J.M. Bowler. 2002. Tundra Swan (Bewick’s Swan) Cygnus columbianus. In: Wernham, C.V., M.P. Toms, J.H. Marchant, J.A. Clark, G.M. Siriwardena & S.R. Baillie (eds.) The Migration Atlas: Movements of the Birds of Britain and Ireland. Pp. 149-153. T. & A.D. Poyser, London.

    Rees, E.C., J.M. Bowler & J.H. Beekman. 1997. Cygnus columbianus Bewick’s Swan and Whistling Swan. Birds of the Western Palearctic Update 1: 63-74.

  • International Swan Census

    A coordinated, international census of Bewick’s Swan is undertaken in Britain and Ireland every five years. The census covers many non-wetland and/or temporarily flooded areas that are not routinely covered by other annual schemes.

    Results from the censuses are presented in various reports and papers. See our Reports & newsletter page.

    Find out more about the International Swan Census

    Wetland Bird Survey and Irish Wetland Bird Survey

    Bewick’s Swan numbers in the UK and Republic of Ireland are monitored annually through the Wetland Bird Survey (WeBS) and the Irish Wetland Bird Survey (I-WeBS), respectively. Although these schemes provide coverage of a high proportion of wintering sites used by Bewick’s Swans, a number of non-wetland or temporally flooded areas are not surveyed, hence a more comprehensive census, that focuses specifically on Bewick’s Swans, is required to estimate total numbers in Britain and Ireland; such a survey is undertaken every five years (see above).

    GSMP age assessments

    The annual breeding success of the Northwest European population of Bewick’s Swan is monitored in Britain through age assessments that are undertaken annually throughout the autumn and early winter. Counters record the number of first winter birds present within a flock and individual brood sizes (i.e. how many young in each family group).

    Results from these age assessments are presented on the ‘Latest results’ tab, and a summary of annual estimates can also be found on the ‘Status summary’ tab.

    Find out more about age assessments

  • Results from 2015/16 [added August 2016]

    Abundance

    WeBS/I-WeBS

    The abundance of Bewick’s Swans in the UK and the Republic of Ireland in 2015/16 was monitored through the Wetland Bird Survey (WeBS) and the Irish Wetland Bird Survey (I-WeBS), respectively. Results from these schemes are presented in survey reports which are available to download from the schemes’ websites.

    International Swan Census

    The eighth internationally coordinated census of the Northwest European Bewick’s Swan population was undertaken in January 2015. The census was organised overall by the Wetlands International / IUCN SSC Swan Specialist Group and coordinated in Britain and Ireland by WWT in partnership with BirdWatch Ireland. The census yielded a total of 4,371 Bewick’s Swans in Britain and 21 in Ireland, which together represent a decline of 38% compared with the Britain and Ireland total in 2010, and is by far the lowest census total to date (Figure 1).

    Figure_BS_1_2016

    Figure 1. The number of Bewick’s Swans recorded in Britain and Ireland during the International Swan Census and the Northwest European population estimate (Beekman et al. 2015), 1984–2015.

    Swans were recorded at 26 sites in England and Wales, from Northumberland to Dorset (Figure 2). The majority of birds (85% of the British total) were recorded at two sites: the Ouse Washes, Norfolk/Cambridgeshire (3,197 birds), and the Nene Washes, Cambridgeshire (528). WWT Slimbridge (Severn Estuary), Gloucestershire, Hickling Broad, Norfolk, and Walland Marsh, Kent, recorded 192, 138 and 90 swans, respectively. All other sites recorded fewer than 50 birds.

    Bewick’s Swans were recorded at four sites in the Republic of Ireland (Figure 2): with one site, Wexford Harbour & Slobs, holding 13 birds, whilst the remaining three sites held fewer than five birds.

    Figure_BS_2_2016Figure 2: Number and distribution of Bewick’s Swans recorded in Britain and Ireland during the International Swan Census, January 2015.

    During the census, the Ouse Washes and the Nene Washes held numbers exceeding the 1% threshold for international importance (220 birds; Wetlands International 2016), whilst WWT Slimbridge, Hickling Broad and Walland Marsh each supported numbers above the nationally important threshold (70 birds; Musgrove et al. 2011). No sites in Ireland supported nationally important numbers (20 birds; Crowe et al. 2013).

    Breeding success

    Bewick’s Swan age assessments were conducted in four regions across England and Wales during winter 2015/16 (Table 1). Age assessments were made in all regions in mid-winter (between 15 and 19 January 2016) because a relatively high proportion of early arrivals (i.e. those present in October and November) comprise mostly non/failed breeders (Rees et al. 1997). Thus, age assessments made in mid-winter are more representative of the population as a whole. The percentage of young and mean brood size was derived from age counts conducted within a five-day window in an effort to avoid any bias that would arise from repeated observations of the same families at a particular site. Regional variation in the percentage of young was also assessed in order to determine any differences in the geographical distribution of family parties.

    Table 1.  The proportion of young (%) and mean brood size for Bewick’s Swans at sites in Britain during the 2015/16 winter.

    Region Total aged Percentage of young (%) Number of broods Mean brood size
    East Central England 1,320 (173) 13.1 98 (173) 1.8
    North England 5 (1) Limited data 1 (1) Limited data
    Southwest England 116 (20) 17.2 13 (20) 1.5
    Overall 1,441 (194) 13.5 112 (194) 1.7

    Regions (counties from which data were received in 2015/16):

    • East central England: Cambridgeshire and Norfolk (WWT Welney/Ouse Washes/Nene Washes)
    • North England: Lancashire (Ribble Estuary)

    Southwest England: Gloucestershire (WWT Slimbridge)

    A total of 1,441 Bewick’s Swans was aged and brood sizes were recorded for 112 families: 98 in east central England, one in northern England and 13 in southwest England. Overall, Bewick’s Swan flocks contained 13.5% cygnets, which is above the previous five-year and ten-year averages (12.7% ± 1.3 SE and 10.5% ± 1.1 SE, respectively) for these sites (Table 1, Figures 4 & 5).  The mean brood size of 1.7 cygnets equalled the previous ten-year mean (1.7 ± 0.09 SE) (Table1, Figures 4 & 5).

    There was variation in the proportion of cygnets recorded across Britain, where the percentage of young was 13.1% in east central England and 17.2% in southwest England (Table 1), although this variation was not statistically significant (X22 =1.6, P > 0.05).

    Figure_BS_4_(2)_2016

    Figure 3: The percentage of young (blue circles), with the rolling five-year mean of % young (red line): five-year mean values were calculated for the five years preceding the year in question. Mean brood size (green triangles) is for Bewick’s Swans recorded at WWT Slimbridge, the Ouse and Nene Washes and the Ribble Estuary combined, 1993/94–2015/16.

    Figure_BS_5_2016Figure 4. The percentage of young Bewick’s Swans recorded at WWT Slimbridge, the Ouse and Nene Washes and the Ribble Estuary, 1987/88–2015/16.

    Discussion

    Overall, Bewick’s Swans wintering in Britain had a reasonable breeding season in 2015 with 13.5% young; above the previous five-year and ten-year means (12.7% ± 1.3 SE and 10.5% ± 1.1 SE, respectively).

    Conditions on the breeding grounds are likely to be important in determining the population’s breeding success, in particular, weather conditions during the short Arctic breeding season (Poorter 1991). Temperatures in the Pechora Delta (in the vicinity of an important breeding area for the species) in May 2015 averaged 6.1°C which was higher than the previous five year average for the area (of 3.5°C) (TuTiempo 2015).

    Results from the 2015 Bewick’s Swan census show a notable decline in the number of birds wintering in Britain and Ireland since the previous census in 2010.However, interestingly, since 2000, Britain has held an increasing proportion of the overall population despite the overall decline in the Northwest European population (Figure 5). Comparatively, census results show a constant decline in the number of Bewick’s Swans wintering in Ireland since the peak count recorded during the 1990 census. Given the large decline observed in Britain during the 2015 census, it will be interesting to see whether numbers elsewhere along the flyway also fell so markedly – at the time of writing, results from other countries are still being collated, but early indications suggest numbers were lower than those recorded during the 2010 census.

    Figure_BS_3_2016

    Figure 5: Percentage of Northwest European Bewick’s Swan population recorded in Britain during the International Swan Census, 1984–2010.

    Acknowledgements

    Special thanks to all observers and Local Organisers who took part in the international census and the productivity surveys, including the WeBS, I-WeBS, Irish Whooper Swan Study Group and GSMP networks. We are especially grateful to Helen Boland and Graham McElwaine for coordinating the census across Ireland.

    References

    Beekman, J., C. Hall, B. Laubek & E. Rees. 2015. International Bewick’s and Whooper Swan Census in northwest Europe. In, Mitchell, C.D. (ed). 2015. Swan News issue no 11/ May 2015. Newsletter of the Wetlands International / IUCN SSC Swan Specialist Group. 28pp.

    Crowe, O. & Holt, C. 2013. Estimates of waterbird numbers wintering in Ireland, 2006/07–2010/11. Irish Birds 9: 545–552.

    Musgrove, A.J., Austin, G.E., Hearn, R.D., Holt, C.A., Stroud, D.A. & Wotton, S.R. 2011. Overwinter population estimates of British waterbirds. British Birds. 104: 364–397.

    Poorter, E.P.R. 1991. Bewick’s Swans Cygnus columbianus bewickii, an analysis of breeding success and changing resources. Ministerie van Verkeer en Waterstaat, Rijkswaterstaat, Directie Flevoland.

    Rees, E.C., J.S. Kirby & A. Gilburn. 1997. Site selection by swans wintering in Britain; the importance of habitat and geographic location. Ibis 139: 337-352.

    TuTiempo: http://www.tutiempo.net/en/ [accessed June 2016]

    Wetlands International. 2016. Waterbird population estimates. wpe. wetlands.org [accessed 26 June 2016].

  • Previous annual results will be archived here. Published results from the International Swan Census can be found on the Reports & newsletter page.

    2014/15 Results

    2013/14 Results

    2012/13 Results

    2011/12 Results

    2010/11 Results

    2009/10 Results

    2008/09 Results

    2007/08 Results

    2006/07 Results

    2005/06 Results

     

     

  • Background

    Bewick’s Swans have been marked, initially just with metal rings, at WWT Slimbridge since 1961 and until the late 1960s this was the only location in Britain where the species was ringed in any number. During this time the study focused on individual recognition of birds by their unique bill pattern (see WWT’s website for more details).

    Then in 1967, a regular colour-marking programme was introduced that enabled information to be gathered about the birds whilst on migration, at staging sites and at other wintering sites (Mitchell & Ogilvie 1997, Rees & Bowler 1996). Individual birds could then be monitored throughout their lifetime to determine factors affecting their pairing and breeding successes, survival rates and site selection. This information could be used to explain changes in the swans population size and distribution and enabled researchers to identify their ecological needs (Rees 2006). Such detailed information was and still is invaluable in supporting conservation efforts for Bewick’s Swan, a species that has declined by 27% between 1995 and 2005.

    At WWT centres, swans are caught in a specially designed ‘swan pipe’ – a long, netted trap which is baited with food to encourage birds to enter, where they can be caught by dropping a gate to close off the entrance. The first swan pipe was built at WWT Slimbridge in 1969 and, following its success, more were built at WWT Welney in 1980 and at WWT Martin Mere in 1990, extending the colour-marking programme to other parts of Britain (Owen et al. 1986, Rees & Bowler 1996).

    Ringers in the Netherlands started regularly marking Bewick’s Swans in 1985 and more recently birds have been caught and ringed at migratory sites in Germany, Denmark and Estonia and on the breeding grounds in arctic Russia (Rees & Bowler 2002). From 1991 to 2008, WWT joined expeditions with the All-Russian Research Institute for Nature Protection to arctic Russia to study the swans on their breeding grounds.

    Resightings of colour-marked Bewick’s Swans have lead to a number of important discoveries, including:

        • confirmation of the migratory route from the breeding grounds to the wintering grounds: the swans migrate from the breeding grounds along the arctic coast of Russia to the White Sea, head southwest across Karelia to the Gulf of Finland and the Baltic coast, following the northern and southern shores of the Baltic to the wintering grounds in northwest Europe (Rees & Bowler 2002).
        • confirmation that Estonia, the White Sea region and the Pechora Delta are vital staging and breeding areas (Rees & Bowler 2002).
        • evidence that swans wintering in different parts of Britain may have different migratory routes. Swans ringed in northwest England and southwest Scotland (at WWT Martin Mere and WWT Caerlaverock, respectively) have a more northerly distribution than those ringed in southern Britain (at WWT Welney and WWT Slimbridge). Further investigation has shown those birds marked in northwest England are more likely to be reported in Denmark, Germany and Northern Ireland, whilst those ringed in the southwest are more likely to be seen in the Netherlands and other parts of Britain (Rees & Bowler 2002).

    WWT colour-ringing

    Bewick’s Swans are caught and ringed every winter at WWT Slimbridge and WWT Welney. This is undertaken as part of our long-term life-history study on the species. Each bird is fitted with a coloured leg ring, as well as a metal ring, and various body size measurements and samples are taken to assess its condition and health. By catching these birds we have been able to identify issues affecting them, such as illegal shooting and lead poisoning (Newth et al. 2011, Newth et al. 2012). This information helps to inform subsequent conservation measures taken to reduce the scale of these threats.

    Ring combinations used
    White leg rings (black lettering) Yellow leg rings (black lettering) Green leg rings (white lettering)
    Alpha/alpha/alpha APA – TXZ EXJ – ZCZ AAA – AES
    Numeric/numeric/alpha 11A-24S
    Numeric/numeric/numeric 396-910

    If you see any colour-marked Bewick’s Swans with these combinations please send your sightings to colourmarkedwildfowl@wwt.org.uk

    Project partners

    We work with the All-Russian Research Institute for Nature Protection, the Danish Ministry of the Environment, Komi Science Centre, the Museum and Institute of Zoology at the Polich Academy of Sciences, and the University of Groningen.

    References

    Mitchell, C. & M. Ogilvie. 1997. Fifty years of wildfowl ringing by the Wildfowl & Wetlands Trust. Wildfowl 47: 240-247.

    Owen, M., G.L. Atkinson-Willes & D.G. Salmon. 1986. Wildfowl in Great Britain; Second Edition. Cambridge University Press, Cambridge.

    Rees, E.C. 2006. Bewick’s Swan. T. & A.D. Poyser, London.

    Rees, E.C. & J.M. Bowler. 2002. Tundra Swan (Bewick’s Swan) Cygnus columbianus. In: Wernham, C.V., M.P. Toms, J.H. Marchant, J.A. Clark, G.M. Siriwardena & S.R. Baillie (eds.) The Migration Atlas: Movements of the Birds of Britain and Ireland. Pp. 149-153. T. & A.D. Poyser, London.

    Rees, E.C. & J.M. Bowler. 1996. Fifty years of swan research and conservation by the Wildfowl & Wetlands Trust. Wildfowl 47: 248-263.

     

  • Survey results

    International Swan Census reports: See the Reports & newsletter page

    Wetland Bird Survey Alerts

    Wetland Bird Survey annual report

    Relevant publications

    AEWA International Single Species Action Plan

    Kear, J. 2005. Ducks, geese & swans. Oxford University Press.

    Newth, J.L., M.J. Brown & E.C. Rees. 2011. Incidence of embedded shotgun pellets in Bewick’s swans Cygnus columbianus bewickii and whooper swans Cygnus cygnus wintering in the UK. Biological Conservation 144: 1630-1637.

    Rees, E.C. 2006. Bewick’s Swan. T. & A.D. Poyser, London.

    Rees, E.C. & J.H. Beekman. 2010. Northwest European Bewick’s Swan: a population in decline. British Birds 103: 640-650.

    Robinson, J.A., K. Colhoun, J.G. McElwaine & E.C. Rees. 2004. Bewick’s Swan Cygnus columbianus bewickii (Northwest Europe population) in Britain and Ireland 1960/61 – 1999/2000. Waterbird Review Series, The Wildfowl & Wetlands Trust/Joint Nature Conservation Committee, Slimbridge. Download

    Other relevant material

    BirdLife International Species factsheet

    British Trust for Ornithology: Bird Facts

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