Whoopers

A scattered flock of white dots, distant on the dark soil of a fenland field and some way back from the railway, can only be a group of wintering swans. Two days ago the swans were too distant and the light too poor to permit identification. Today, on a later train and in better weather, the birds are feeding much closer to the curving track. As the train approaches so the dots resolve themselves into whooper swans, long-necked and with wedge-shaped bills. A rough and ready count suggests a flock in excess of 200 individuals; winter visitors from their Icelandic breeding grounds.

Over the long term we have seen an increase in the size of the population wintering in Britain, something which has been brought about by an increase in the Icelandic breeding population. A successful breeding season is reflected in the ratio of young to adult birds, the swans helpfully arranged in family parties and the youngsters readily identifiable from their soft grey plumage tones. Calculating that ratio is not something I can do from a fast-moving train and I am tempted to return by car on another day.

The numbers wintering here may change from one winter to another, the birds distributing themselves in relation to the weather and feeding opportunities. There is also a degree of movement within a winter and a period of cold weather on the Continent can push birds into the southeast of England and East Anglia. My impression is that there are fewer here this year but we will only know for certain once the results of monitoring projects, like the Wetland Birds Survey, are published.

Although I encounter wintering swans across East Anglia there is something about the fenland landscape that seems to fit best with these birds. Perhaps it is the way in which their crisp white plumage contrasts with the richly dark soils or the often-brooding skies that are such a feature of the fenland washes. Late winter is very much the time for these birds and trips out to search for them have become part of my winter birdwatching routine. The swans will be here for a few more weeks yet, so there is still time for more encounters.

Changing waterfowl require greater understanding

The latest review of waterbird populations in the UK makes interesting reading. At first glance it suggests contrasting fortunes for many of the species with which we share these islands. The review, jointly published by the BTO, RSPB and JNCC, stems from the efforts of some 3,000 volunteer counters. These volunteers participate in the synchronised monthly counts that take place across our many inland and coastal waterbodies.

While some species reached new ‘highs’ in terms of their population levels, others reached all-time lows. An examination of the ‘winners’ and ‘losers’ reveals that many of the ‘winners’ are introduced species whose naturalised populations continue to expand. These include Egyptian Goose, Mandarin Duck and Barnacle Goose. However, in with these are genuine colonists like Little Egret, a species expanding north on the back of global climate change.

The numbers of some species reflect breeding conditions elsewhere, the UK being a wintering ground with little or no breeding population of its own. A poor breeding season elsewhere may see fewer birds available to make the journey to our shores. The recent downtown in wintering numbers of Bewick’s Swans was once thought to be linked to a contraction eastwards in the wider European wintering range. However, recent research has revealed a decline in the overall population rather than just a shift in distribution. In contrast, our population of wintering Whooper Swans has continued to increase, with most of our visiting Whoopers arriving from Icelandic breeding grounds. The nature of the survey also enables the volunteer counters to gather information on breeding success for some species. In the case of the Whooper Swan, cygnets accounted for 16.8% of the birds present, slightly up on the previous winter.

The estuaries around Britain & Ireland are important wintering sites for many wading birds and these are also surveyed by the volunteers. Again fortunes appear mixed, with some notable increases seen in Avocet (a real conservation success story), Grey Plover and Sanderling. Balanced against this is the apparent news that Ringed Plover and Dunlin have both hit all time lows. Britain has eight sites of international importance for Ringed Plover but, while the decline might seem worrying, news of increasing numbers at sites elsewhere in Europe (notably The Netherlands) suggests that what we are actually seeing is an eastward shift in the core wintering range, perhaps linked to a run of mild winters.

Taken as a whole, this report highlights the need to monitor the changing fortunes of these birds at a much wider spatial scale, since a decline here may not mean that the population is falling, merely that it is now wintering elsewhere. Fortunately, our knowledge of waterbirds is increasing, placing our understanding into a wider context.

Catching up with old friends

Hunkered down just off the verge I feel like part of the fen, a large sod of thick peaty soil, newly turned by the plough to be weathered by a wind that races in off the North Sea. It’s at times like this that the words of Noel Coward spring to mind; ‘very flat, Norfolk’ and little to stop a wind that has its chilly origins many hundreds of miles to the northeast. I am pressed down low to escape the worst of the wind, to keep myself warm and, more importantly, to keep my telescope steady as I scan the distant flock of Whooper Swans feeding in the next field over.

Even though I feel exposed and uncomfortable under these grand skyscapes, I try to come here each winter to seek out the swans that feed on the fields around Welney. For the swans too, this is something of an annual pilgrimage; an autumn migration that draws them here from breeding grounds spread across Iceland. It is the combination of secure roosting sites and nearby feeding opportunities that attracts the swans and as many as 3,500 may be present during the middle of winter.

Many of the birds arrive in small family parties, the youngsters readily distinguishable from their parents. Some of the birds carry rings, invariably fitted on the breeding grounds, with a few individuals additionally marked with special ‘darvic’ rings that can be read at a distance by telescope. Such rings enable researchers (and interested birdwatchers) to collect information on the whereabouts of individual birds without the need to recapture them. Over time, subsequent resightings of an individual can help to build up a detailed picture of its wintering grounds, together with arrival/departure dates for the movements between breeding and non-breeding sites. Records can be submitted to the Wildfowl and Wetlands Trust who will then send back a spreadsheet detailing the history of the bird(s) you have seen. Among those that I recorded during last winter was an individual first ringed in August 2004 at Bardardalur in Iceland. This particular individual has wintered at or near Welney each winter since. The reports for certain other individuals show a degree of exchange with other sites, including the Wildfowl and Wetlands Trust reserve at Martin Mere in Lancashire and the River Tweed catchment in the borders.

As well as the challenge of reading the rings as the swans feed, there is the delight of noting down a ring number and knowing that it will add to our understanding of these heavyweight waterfowl. There is also the sense of expectation that you might just catch up with an old friend, a swan you have seen in a previous winter.

Swans on the up

The Fens can seem rather bleak and inhospitable at this time of the year, exposed to a wind that whips in off the North Sea and with an expanse of sky dark with threatening clouds. Yet this unique part of East Anglia attracts huge numbers of wildfowl, counted among which are sizeable numbers of our two migratory swans. Drawn to this area by the combination of secure roost sites and available winter food, whooper and bewick’s swans gather annually on the Ouse Washes, centred around the Wildfowl & Wetlands Trust reserve at Welney.

The bewick’s swans, of which 5,000 or so winter on the Ouse Washes, originate from breeding grounds in western Siberia. These birds migrate west to winter in the Netherlands, Britain and Ireland. Some 50% of those wintering in Britain gather on the Ouse Washes and, during January, the washes may be the most important site for the species anywhere in Europe. Traditionally, the swans would have grazed on aquatic and semi-aquatic plants taken from areas of marsh and flooded pasture. However, since the 1970s there has been a noticeable move onto arable land, with the birds favouring fields with sugar beet, potatoes or autumn sown cereals. The cereals become more important towards the tail end of winter. Each morning the swans leave the safety of open water on which they roosted over night to gather on the arable fields that lie just off the washes.

The larger whooper swans are among the heaviest migratory birds, with adult males averaging around 10kg. The individuals wintering here in East Anglia will, for the most part, have come from the Icelandic breeding population. Those from breeding grounds in Finland and NW Russia winter on the continent but there is a small amount of interchange between the two populations (with an estimated 200 Finish birds wintering here and 600 Icelandic birds wintering on the continent). Like their smaller cousins, the whoopers make good use of the arable land and the area around the Ouse can easily attract 3,500 individuals during the middle of winter. Interestingly, both species of swan arrive in family parties and this has enabled researchers to gain an understanding of their annual breeding success. Young birds with their parents can be readily identified and it is possible to calculate the proportion of youngsters within the wintering herds (groups of swans are called ‘herds’ not ‘flocks’). The most recent figures demonstrate that roughly 1 in 10 swans is a youngster, a figure that has declined over recent years, suggesting a decrease in breeding success. The swans will begin to depart from the middle of the month so it is worth making a trip to Welney to see this winter spectacle.