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 – 2014/15.

    Season Percentage of young (%) Mean brood size
    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 2014/15 [added September 2015]

    Abundance

    WeBS/I-WeBS

    The abundance of Bewick’s Swans in the UK and the Republic of Ireland in 2014/15 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 8th census of Bewick’s Swan in Britain and Ireland was undertaken in January 2015. This census is carried out every five years and the results of the latest will be available in late 2015.

    The 7th census in January 2010 produced a British and Irish total of 7,079 Bewick’s Swans, a decrease of 1.9% compared with the 2005 census (Figure 1). A brief summary of the results was presented in the 2011/12 results for Bewick’s Swan (see the ‘Previous results’ tab).

    Figure_BS_1_2013

    Figure 1. Number of Bewick’s Swans recorded in Britain and Ireland during the International Swan Census, 1984-2010.

    Breeding success

    Bewick’s Swan age assessments were conducted in four regions across England and Wales during winter 2014/15 (Table 1) as part of a coordinated assessment of breeding success conducted within a three-day window that coincided with the International Swan Census (held on 17/18 January). Such coordination helps to avoid bias that could arise from repeated observations of the same families at a particular site. Mid-winter is the best period for this assessment because a relatively high proportion of early arrivals (i.e. those present in October and November) are non/failed breeders (Rees et al. 1997), thus age assessments made in mid-winter are more representative of the population as a whole. Regional variation in the percentage of young was also assessed in order to determine any differences in the geographical distribution of family parties.

    A total of 3,633 Bewick’s Swans was aged and brood sizes were recorded for 219 families: 209 in east central England, three in northern England and seven in southwest England. Brood sizes were not determined for flocks surveyed in Wales. Overall, Bewick’s Swan flocks contained 10.3% cygnets and the mean brood size of pairs with young was 1.5 cygnets (Table 1).

    Table 1.  The percentage of young (%) and mean brood size for Bewick’s Swans at sites in Britain during the 2014/15 winter (regions defined below).

    Region Total aged Percentage of young (%) Number of broods Mean brood size
    East Central England 3,337 10.2 209 1.5
    North England 39 15.4 3 limited data
    Southwest England 192 7.3 7 2
    East Wales 65 18.5 no data no data
    Overall 3,633 10.3 219 1.5

    Regions (counties from which data were received in 2014/15):

    • East central England: Cambridgeshire and Norfolk (WWT Welney/Ouse Washes), Kent, Suffolk
    • North England: Lancashire (WWT Martin Mere/Ribble Estuary), Yorkshire
    • Southwest England: Gloucestershire (WWT Slimbridge)
    • East Wales: Flintshire, Monmouthshire

     

    There was variation in the proportion of cygnets recorded across Britain, with the percentage of young ranging from 7.3% in southwest England to 18.5% in east Wales, although sample sizes varied considerably (Table 1). Variation between all sites in the proportion of juveniles recorded was statistically significant (X23 = 7.7, P = 0.05).

    The mean percentage of young in flocks at and around WWT centres (Martin Mere/Ribble Estuary, the Ouse Washes and Slimbridge), where data are collected annually, was 9.7% (n = 3,314), which was similar to the previous ten-year average (10.5% ± 1.1 SE) but below the previous five-year average (12.6% ± 1.4 SE) for these sites. The mean brood size of 1.5 cygnets (213 broods) was also below the previous ten-year mean (1.8 ± 0.09 SE) (Figures 2 & 3).

    Figure_BS_2_2015

    Figure 2: The percentage of young (blue circles), with the rolling five-year mean of % young (red line), and mean brood size (red triangles) of Bewick’s Swans recorded at WWT Slimbridge, the Ouse Washes/Nene Washes and WWT Martin Mere/Ribble Estuary, 1990/91-2014/15. Five-year mean values for the percentage of young were calculated for the five years preceding the year in question.

    Figure_BS_3_2015

    Figure 3.The percentage of young Bewick’s Swans recorded at WWT Slimbridge, the Ouse Washes/Nene Washes and WWT Martin Mere/Ribble Estuary, 1984/85–2014/15.

    Discussion

    Overall, Bewick’s Swan had a poor breeding season in 2014 with 10.3% young recorded in flocks wintering in Britain. Flocks in and around WWT centres comprised 9.7% young which was similar to the previous ten-year average (10.5%) but below the previous five-year average (12.6%) for these sites.

    Conditions on the breeding grounds are 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 and June 2014 averaged 0.9°C and 8.4°C, respectively, which was lower than the previous five year averages for the area (of 3°C and 9.8°C, respectively) (TuTiempo 2014).

    Acknowledgements

    Special thanks to all observers who took part in the International Swan Census.

    References

    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 2015]

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

    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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