The Famous Berwick SwansOver the years the town of Berwick-upon-Tweed has become home to the second largest mute swan colony in Britain. The swans are now such a familiar feature of the Tweed estuary that they have become a well-known tourist attraction, and at peak times almost 800 birds have been counted on the river. The Berwick herd is what is known as a ‘moulting colony’, and this means that numbers fluctuate throughout the year. There are around 200 permanent residents (mainly non-breeding adults and juvenile birds) but the size of the herd increases in late summer and through the winter as swans from other areas arrive to undergo the annual moult or to take advantage of the rich feeding at the Tweed estuary.Not all mute swans join moulting colonies: birds that nest and rear young will moult on their own breeding territory, but may fly in as a family group to join the Berwick herd once the moult is completed. Other young birds arrive at Berwick from October onwards to overwinter, or for longer periods. When the moult is completed many of the adult birds return to their home waters.During the six week period of the moult swans require a steady supply of food. The wing pinions are among the first feathers to be shed, leaving the birds completely flightless and unable to visit favoured feeding grounds, so it is not surprising that many choose to gather on estuaries such as the Tweed before the moult begins. Britain’s estuaries remain ice-free during the winter months, and are one of the most fertile of all natural environments. Around half of Europe’s waders and huge numbers of wildfowl overwinter in and around our estuaries, and although we usually think of mute swans as freshwater birds they regularly eat seaweeds and algae in salt water. In autumn it is not unusual to see groups of Berwick swans swimming round the pier and into the sea bay at Meadow Haven to feed along the shore.Britain’s largest mute swan colony at Abbotsbury in Dorset is unusual in that the birds nest close together in a colony, having been fed, provided with nest sites, and cared for by swanherds for almost 900 years. In contrast, the Berwick swans do not breed at the estuary, and the nearest nesting site is several miles upstream at the mouth of the river Whiteadder. It is, however, possible that Berwick’s past connections with royalty meant that in medieval times swans were farmed locally to provide food for state banquets.Accurate records of the numbers of swans at Berwick have only been kept since the 1950’s, but it is clear that the population increased considerably in the latter part of the twentieth century. Elderly residents report having seen very few swans at the beginning of the century, but by the 1950’s over 200 birds were being recorded annually, and in September 1994 a record 787 birds were counted. This increase in numbers mirrors the growth of the mute swan population throughout the country as a whole.