In 1964, Sir Peter Scott found that each individual Bewick's Swan could be identified by the pattern of yellow and black on its bill.
This heralded nearly 40 years of study of the species that continues today. Unlike most bird species, individual Bewick's Swans can be identified by trained observers by identifying their unique bill pattern. Each individual observed by WWT researchers is given a unique name and their bill pattern is drawn and added to WWT's ever-growing database. This information enables their patterns, movements and behaviour to be monitored and recorded.
Bewick’s Swans wintering at Slimbridge and other WWT centres are ringed enabling them to be identified abroad to build a dossier of each bird’s global movements and relationships. This data is used to understand each bird’s social and breeding behaviour, life history, site fidelity and feeding ecology, all of which help determine the factors that affect their survival. This valuable information enables WWT researchers to understand more about how to protect them and their habitat.
Illegal Hunting threat
To better understand the fall in numbers WWT is conducting a new wave of research into the illegal hunting of Bewick’s Swans, as well as their close relative the Whooper Swans. Swans will be caught and X-rayed at four WWT centres to find out about the injuries they are carrying. Many swans carry shot in pellets in their bodies that they carry around for the rest of their lives. This research into the effect of poaching will help determine exactly how breeding potential can be affected which will help in the battle against illegal hunting.
Background
Bewick's Swans are the smallest and the rarest of the three species of swan found in the British Isles. The species was named by the scientist William Yarrell in 1830 to honour the ornithologist, engraver and bird illustrator, Thomas Bewick.
WWT conservation action
Bewick’s Swans need protection. Not only are their breeding habitats being steadily worn away by development the birds are also targets for illegal hunters. Numbers have been declining in recent years at Slimbridge – from a peak of 610 counted on one day alone in January 1979, we now see about 300 each winter. Further study will show whether this is due to a decrease in the size of the population, to the swans wintering further east due to the mild recent weather caused by climate change, or to a combination of factors.