Walking round Fewston Reservoir in mid-December a loud bugle call announced a lone swan sailing down the centre, its voice and straight-necked appearance giving a clue to its identity, confirmed by the large yellow wedge on its bill as a whooper swan, a creature of totally different character to the familiar curve-necked mute swans so familiar from the River Wharfe.
This whooper had perhaps been separated from a flock that would have originated on its breeding grounds in Iceland. Their main wintering area is around the Ouse Washes where numbers can reach 4000. On the other side of the Pennines, Martin Mere and the Ribble Estuary can hold up to 2000 while smaller numbers see out the winter in the Hebrides and along the Scottish west coast. Given that most whoopers migrate through Yorkshire earlier, in October and November, this individual might have come from one of these latter groups moving further south.
Very similar in appearance, although shorter-necked and with less yellow in the bill is the Bewick’s swan, another bird breeding in the far north although much further east, in Siberia, from where they migrate southwest to winter in Denmark, Holland and Britain. Large numbers, usually over 5000, still winter around the Wash so their flight lines are less likely to take them over Yorkshire, with those few seen here probably making for northwest England or the Severn Estuary where declining numbers in recent years have been measured in hundreds.
While I regularly see small groups of whoopers on Lindley Wood (pictured), Fewston and John O’Gaunts Reservoirs and other observers have recorded much bigger herds, in recent years I have seen no Bewick’s swans in Wharfedale. My last record was of a group of a dozen on Knotford Nook in November fully 35 years ago during a spell of hard weather, a week after a half dozen whoopers had flown into the same spot. Wharfedale Naturalists Society records paint a similar picture with few records of Bewick’s swans after the second half of the 1980s.
It seems likely that, as we are on the western fringe of its range and with Britain experiencing warmer winters as a result of global warming, the number of Bewick’s swans arriving here is likely to fall further. A similar phenomenon has already been noticed with other wildfowl, with goldeneye ducks as just one example.
By Denis O’Connor
Wharfedale Naturalists Society