Addressing the Bewick‘s Swan’s Decline
By Eileen Rees
Globally, there are three recognised populations of Bewick’s Swans (Cygnus columbianus bewickii). Over-wintering numbers of one of these populations, the northwest European population, have fallen from around 29,000 birds in 1995 to fewer than 18,000 at present (Rees & Beekman 2010). In response, the Bewick’s Swan has recently been classified as endangered on the European Red List of bird species (BirdLife International, 2015).
Despite the declining numbers of Bewick’s Swans, a growing conservation effort is aiming to understand and reverse the decline. In September 2009, a group of swan experts met at a workshop held in Saint Petersburg, hosted by Lenoble Priroda, and organised jointly by Wetlands International (WI), the WI-IUCN SSC Swan Specialist Group, and the Wildfowl and Wetlands Trust. Participants identified potential threats to the birds and developed the monitoring, research and conservation work required to halt and reverse the population decline. Ongoing conservation efforts aim to halt the decline and restore the population to at least 23,000 individuals (Nagy et al. 2012).
In 2014, the Wildfowl & Wetlands Trust (WWT) launched the successful ‘Hope for Swans’ appeal to fund an ongoing research programme to investigate the causes of the population decline. This programme will draw together Bewick’s Swan researchers from across different range countries. In the first part of the project, we will assess changes in Bewick’s Swan demography (i.e. breeding success, survival), and understand the contribution that such changes have made to the population change (Wood et al. 2016). In the second part of the project, we will combine field data with simulation models to assess whether key wintering areas (such as the Ouse Washes in eastern England) can provide sufficient undisturbed feeding opportunities to allow the swans to survive the winter and depart for their breeding grounds in good condition.
BirdLife International 2015. European Red List of Birds. Office for Official Publications of the European Communities, Luxembourg.
Nagy, S., Petkov, N., Rees, E.C., Solokha, A., Hilton, G., Beekman, J. & Nolet. B. 2012. International Single Species Action Plan for the Northwest European Population of Bewick’s Swan (Cygnus columbianus bewickii). AEWA Technical Series No. 44. Bonn, Germany.
Rees, E.C. & Beekman, J.H. 2010. Northwest European Bewick’s Swans: a population in decline. British Birds 103: 640–650.
Wood, K.A., Newth, J.L., Hilton, G.M., Nolet, B.A. & Rees, E.C. 2016. Inter‐annual variability and long‐term trends in breeding success in a declining population of migratory swans. Journal of Avian Biology. DOI: 10.1111/jav.00819