Thursday, 9 December 2010

Ouse up and Ouse down?

The Ouse Washes are officially classed as ‘Unfavourable’ condition, due to the increased incidence of summer flooding and the poor water quality. Breeding waders have declined, from an overall total of 900+ pairs in 1990 to around 450 this year. Most notably, Black-tailed Godwits have declined to just 2 or 3 pairs at this former stronghold, and Snipe have also declined sharply.

However, ‘every cloud has a silver lining’ as they say. Under the wetter summer conditions, breeding duck have increased, with average counts over the last five years of 161 pairs of Shoveler, 110 of Gadwall and 9 of Garganey. Spotted Crakes also increase in the wetter years, with up to 4 ‘whippers’ in recent times. These ups and downs mirror the cyclical patterns of species seen in some natural floodplains in Europe – more ducks, grebes and terns in wet years, more waders and Corncrakes in drier years.

The influence of the water regime also applies in the winter, deep floods favour Pochard, Tufted Duck and Coot, shallow floods favour the dabblers; Shoveler, Wigeon, Pintail and Teal.  The highly mobile birds respond rapidly as the water levels change.  There are of course many external influences at work as well. Many wildfowl are ‘short-stopping’ on the continent, due to recent milder (!?) winters. The wild swans, perhaps the washes most notable winter visitors, also show differing trends, but this is not down to water regime. Whilst Whoopers (from Iceland) have steadily increased to over 5,000, Bewick’s have declined to around 3,500. The decline in Bewick’s is concerning as it is clear that poor breeding success is at least part of the cause. The number of juvenile birds accompanying the adults has sharply declined in recent years.

Today the washes were frozen stiff. Whoopers and Bewick’s fed out in the adjacent beet fields, returning in the late afternoon to roost on a small area they keep ice-free. Around 1600 have returned so far this winter. It may be ‘unfavourable’ but the Ouse Washes are still a fantastic place for birds.

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