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Wetland Bird Declines

Is climate change to blame?

Waterbird counts [that have been conducted for over 50 years] reveal falling numbers of some of the internationally important bird species in the UK, in the period 2001 to 2004, according to newly published reports produced by the British Trust for Ornithology and the Wildfowl and Wetlands Trust.

Three thousand birdwatchers will be donning warm clothes this weekend to take part in the first Wetland Bird Survey (WeBS) count of the year. Is it still going to be difficult to find good numbers of Shelduck? Are Grey Plover numbers still going down? Will it be another record count for Little Egrets?

Each WeBS counter has his or her own patch – perhaps the shore of an estuary to walk along or an inland lake. By counting the birds on their patches, once per month throughout the winter, WeBS volunteers are helping to monitor these important habitats by tracking the status of the waterbirds they support, many of which spend the summer nesting in Arctic regions, vulnerable to the effects of climate change.

The UK’s wetlands are home to up to ten million wildfowl, waders and gulls during the winter, and a large proportion of this total is found on estuaries. For example, the Wash (between Lincolnshire and Norfolk) can support a staggering 350,000 waterbirds at peak times, with totals of over 100,000 birds also regularly recorded from Morecambe Bay, Ribble Estuary, North Norfolk Coast, Humber Estuary, Thames Estuary, Dee Estuary, Solway Firth and Mersey Estuary, all of these being estuarine sites. Our relatively warm winter conditions (compared to the European mainland at least), largely attributable to the Gulf Stream, should be ideal for these Arctic and sub-Arctic breeding birds but there are now signs that all is not well for a range of geese, ducks and wading birds. For species such as the Grey Plover and Dark-bellied Brent Goose, whose populations peaked in the early 1990s after long periods of increase, numbers are now declining steadily.

It is not all bad news, however, with numbers of Little Egrets, Pink-footed Geese, Gadwall and Black-tailed Godwit all reaching record levels.

Andy Musgrove, of the BTO, who is the Wetland Bird Survey National Coordinator said: “Different species are changing in numbers in the UK for a great variety of reasons but one possibility is redistribution due to climate change. As we see a trend towards milder winters, many species are able to spend the winter closer to their breeding grounds, and thus a decreasing proportion of their populations finds it necessary to migrate as far as the UK. Even within the UK, we are seeing a shift in wintering distribution away from the milder south and west towards areas further north and east. These findings have only been possible due to the time devoted to WeBS by thousands of volunteers across the length and breadth of the UK.”Peter Cranswick of the Wildfowl & Wetlands Trust said: "The wealth of information provided by WeBS for over 50 years is invaluable for conservation of waterbirds and wetlands. Only in the last five years, however, have we become aware of the considerable importance of UK nearshore marine waters - particularly for Common Scoter and Red-throated Divers. A programme of aerial surveys is now providing complementary information to that from volunteers, to help conserve these species and marine sites. Wildfowl & Wader Counts draws together all of these survey data into a one-stop-shop for numbers and distribution of non-breeding waterbirds in the UK."

Rowena Langston, who represents RSPB on the WeBS steering group said: “The UK is host to waders from many parts of the globe, and protecting these birds and sites of importance for them is a duty that could not be adequately undertaken without WeBS and the dedication of its volunteers. WeBS data play an important role in informing decisions on major developments affecting sensitive sites, for example recent port expansion proposals for Dibden Bay on Southampton Water and London Gateway on the Thames.”Helen Baker, JNCC, said: “The UK’s estuaries are hot-spots for conservation and many are protected because of the important populations of birds that they attract. The results from the Wetland Bird Survey are crucial for helping us to manage our wetlands for their birds and the publication of them in the annual report gives easy access to conservation practitioners. WeBS indices and site-by-site results give us early indications of declines and this helps us to identify priority research and inform policies for waterbird conservation.”

4th July 2014