Whooper Swan Cygnus cygnus
Fairly common passage migrant and winter visitor, with a notable increase since the late 1990s. Occurs mainly October-April, exceptional in summer.
Part of a Whooper Swan flock near Kirton Marsh on January 20th 2014. Two of the birds (not in this photograph) had been colour-ringed in Iceland the previous autumn (Phil Hyde).
WeBS reports indicate that the English wintering population of Whooper Swan grew by 425% over the 25 years to 2017/18 and 56% of that growth was in the last 10-year period. The Atlas reports that up to the late 1990s at least, large flocks above 50 were rarer for Whooper than Bewick's Swan C. columbianus. A useful chart in LBR 2015 shows peak winter numbers from 1978/79 to 2014/15. Annual peak counts were below 50 up to 1994/95 and reached 100 in 1998/9, 200 in 2005/6 and 400 in 2014/15. In January 2019 a massive 864 were counted across all sites. It is possible some of these birds were moving between sites. The main locations currently are the coast from Donna Nook to Anderby, Nocton/Branston Fens, Frampton Marsh and Wroot. March sees large movements of birds relocating back towards Iceland. The largest recorded was a flock of 500 seen flying over Willow Tree Fen on Mar 13th, 2016. Summering of presumably injured birds is becoming more frequent but there have been no suggestions of breeding pairs. In January 2014 two Whooper Swans in a small herd near Frampton Marsh carried colour rings subsequently shown to have been ringed in the same catch in Iceland August 2013.
Reference
Balmer, D.E., Gillings, S., Caffrey, B.J., Swann, R.L., Downie, I.S., & Fuller, R.J. (2013). Bird Atlas 2007-11: the breeding and wintering birds of Britain and Ireland. BTO Books, Thetford.
(Account as per new Birds of Lincolnshire (2021), included September 2022)