Species update
Milder winters have proved beneficial to the Mute Swan population, says Kate Risely
MUTE SWANS ARE a familiar and mostly peaceful presence on nearly all of our lakes and waterways, even in busy towns, a habituation born of hundreds of years of semi-domestication. Under extensive and tightly-controlled systems of ownership dating back to at least the 15th Century, and likely long before, wild birds were rounded up, marked, had their wing tips cut off, and were controlled as a resource for the table. The right to the local swans was a privilege bestowed by the crown on nobles, wealthy landowners and the clergy, with severe penalties for poachers. One remnant of this practice is the traditional activity of ‘swan upping’, in which the Mute Swans on one section of the Thames are rounded up each year and marked by the Vintners and Dyers livery companies, descendants of medieval trade guilds. Today, the upping is ceremonial; birds are marked with rings, rather than bill nicks, and are counted and checked for entangled fishing tackle, rather than taken to eat. Another echo of this long cultural tradition can be found in the widespread, yet hazy, belief that swans are specially protected because they belong to the Queen. While there is a royal prerogative, this does not translate to any practical additional protection for today’s Mute Swans, above that accorded to most wild birds. This management of Mute Swans continued in areas such as the fens until the end of the 18th Century, and our current population is mainly descended from these semi-domesticated ancestors. Historical records indicate that in the 16th Century there were an estimated 24,000 Mute Swans in the fens alone, a testament to the extensive rivers and wetlands that were once found in Britain, as well as protection. The first British Mute Swan Census was organised by the BTO in 1955, and resulted in a national population estimate of about 20,000 birds. Since then, surveys and censuses organised by the BTO and the Wildfowl and Wetlands Trust revealed a general increase in numbers between the 1960s and the 1980s, and, today, there are thought to be about 30,000 individual Mute Swans in the UK, although the large proportion of nonbreeders means that this only includes about 6,000 breeding pairs. The population increase in recent years is thought to be partly due to the reduction of lead poisoning. Mute Swans mainly feed on pondweed, and they swallow grit to help them grind down vegetation. This habit means they are vulnerable to poisoning from discarded anglers’ weights and spent gunshot. This was a major cause of mortality in the 1970s, but fortunately a subsequent ban on lead weights for fishing has reduced, if not eliminated, swan deaths through lead poisoning. Unlike other swans, our Mute Swans are very sedentary, and don’t generally move far between the winter and breeding seasons. However, they suffer in freezing conditions, and are more likely to move long distances in search of open water. There have been relatively few records of ringed birds moving overseas, and the furthest recorded journey was by a bird that was ringed in Lithuania, and recovered in Scotland in January 1959. Generally, milder winters appear to be benefiting this species, and their thriving population has also been attributed to an increasing reliance on gravel pits and ponds, and also to improvements in our water quality..
Unlike other swans, our Mute Swans are very sedentary, and don’t generally move far between the winter and breeding seasons