Each winter Britain sees the arrival of millions of waterbirds of many different species from the Arctic and northern Europe. A report – Waterbirds in the UK 2007/08 – published today highlights some startling changes in the fortunes of these visitors over the last decade.

An analysis of the 50 most widespread winter-visiting wetland birds (excluding gulls) shows there have been some very dramatic changes over the last decade. The birds faring the worst, compared with a decade ago, include: ringed plover; pochard; bar-tailed godwit; and the Greenland white-fronted goose. The five species recording the greatest increases over the period include: little egret; whooper swan; black-tailed godwit; avocet and the Greenland barnacle goose.

For some declining species, such as the ringed plover and bar-tailed godwit, it seems they are shifting away from wintering in the UK, preferring to spend the winter in continental Europe. However, those species which have increased in number are increasing for a variety of reasons. Avocets are believed to have increased because of milder winters and targeted conservation action, while the black-tailed godwit and whooper swan, which migrate from Icleand, are thought to be increasing because of subtle changes in farming there, possibly linked to climate change.

Dr Mark Avery is the RSPB’s Conservation Director. He said: “Two aspects of this long-running study really stand out. Firstly, that bird populations change over time, understanding this is critical to developing future conservation strategies. Secondly, the UK’s wetlands – and particularly those on the coast – are of enormous importance to the survival of a great number of waterbirds which migrate from many other countries.

“The protection and wise management of our wetlands is a priority to ensure that they continue to provide a lifeline to bird populations in the face of climate change, a view recognised by the Convention on Wetlands of International Importance.”

Chas Holt, WeBS organiser, BTO, commented: “The changes in waterbird populations identified each year by Wetland Bird Survey (WeBS) volunteers highlight the importance of monitoring our wetlands. Without the dedicated efforts of WeBS volunteers thoughout the UK, we would know far less than we do about how our waterbird populations are faring, and which sites are of most importance for them. Future research and conservation efforts, both at the national and international level, can be suitably directed using information collected by these volunteers.”

Richard Hearn, Head of Species Monitoring at WWT, said: “Where declines of these migratory waterbirds have been noted in the UK, we must gauard against assuming these birds are wintering further east in parts of Europe previously too cold. Climate-related changes in distribution have the potential to mask more serious conservation problems, so it is more important than ever that we get the complete picture by working with partners abroad to monitor these birds across their flyways.”

David Stroud, of JNCC, said: “The UK has been working with Greenland, Iceland and Ireland to develop an international action plan for Greenland White-fronted Geese under the Agreement on the conservation of African-Eurasian migratory waterbirds (AEWA). AEWA provides a legal framework for countries to work together to conserve such waterbirds that move between many countries in the course of their annual migratory cycle. The monitoring data from WeBS are essential to enable the UK to fulfil its obligations under AEWA and other international treaties.”

The annual report is based on the fieldwork of around 3000 bird surveyors participating in synchronized monthly counts at wetlands, including estuaries, marshes, lakes and reservoirs, across the UK. The UK is of global importance for wintering wetland birds and 225 wetland sites host one or more species in internationally-important numbers and 85 hold an average of 10,000 or more birds.

Over the last five years the most important sites for waterbirds in the UK have been (in order with the average number of birds): The Wash (371,308); the Ribble Estuary (238,160); the North Norfolk coast (206,703); Morecambe Bay (197,291); and the Thames Estuary (186,302).

The report is produced by the British Trust for Ornithology, the RSPB, and the Joint Nature Conservation Committee, in association with the Wildfowl & Wetlands Trust.

The species which have increased the most between 1997/98 and 2007/08 are:

• Little Egret 811%
• Whooper Swan 135%
• Black-tailed Godwit 79%
• Avocet 73%
• Greenland Barnacle Goose 66%
• Little Grebe 60%
• Re-established Greylag Goose 50%
• Shoveler 43%
• Gadwall 31%
• Canada Goose 27%

The species which have declined the most between 1997/98 and 2007/08 are:

• Ringed Plover -57%
• Pochard -44%
• Bar-tailed Godwit -42%
• Common Scoter -37%
• Greenland White-fronted Goose -37%
• Dunlin -31%
• Shelduck -31%
• Goosander -29%
• Eider -29%
• Bewick’s Swan -28%

A total of 225 wetland sites in the UK support one or more species in internationally-important numbers. A number of sites, on average over the last five winters, held over 50,000 birds each winter. The sites listed below include the average number of birds present each winter between 2003/04 and 2007/08.

Reports that spring may be delayed this year do not seem to have reached the birds at WWT London Wetland Centre. Some birds have already surprised visitors by singing unusually early.

Birdwatchers heard the first bittern, a rare type of heron, ‘booming’ in early January this year. Male bittern normally make their distinctive mating call from April onwards in an effort to attract a mate. The call is a ‘booming’ noise which carries through reedbeds and can be heard up to at least two miles away. While five of these secretive birds have been spotted at the centre this winter – an unusually high number, especially for a site so close to the heart of the capital – this is the first record of one booming at London Wetland Centre. There are roughly 75 breeding male bittern in the UK.

And to add to the confusion this week a willow warbler has been heard singing on the edge of the Wetland Centre site. These small songbirds typically spend summer in the UK and fly south for the winter. Willow warbler typically fly over 3,000 miles to West Africa. The centre’s staff are amazed at this bird’s early arrival and are keen to discover if this is the first willow warbler to be heard calling this year anywhere in the country.

Adam Salmon, Reserve Manager, said “It is totally unprecedented for a willow warbler to be singing this early. We would usually see these birds arriving in the UK from mid March, and singing towards the beginning of April.” It is possible that unusual weather in southern Europe or West Africa, where the warbler is likely to have been spending winter, may have encouraged the bird to fly home early.

WWT London Wetland Centre is a 105 acre wildlife haven close to the heart of the capital. Over 180 bird species have been recorded on site and it is also home to eight species of bat, a thriving colony of water voles (the UK’s most endangered mammal), amphibians, reptiles, moths, butterflies and dragonflies. Some exceptionally rare sightings have been recorded over the 10 years that the site has been open including Roesel’s bush cricket, Nathusius’ pipistrelle and Leisler’s bats, cattle egret, night heron, Montagu’s harrier, lesser emperor dragonfly and white-spotted bluethroat. The reserve is a Site of Special Scientific Interest (SSSI) and was recently described by Chris Packham, BBC Springwatch presenter, as “one of the most important conservation projects of the past century… giving millions of people the opportunity to encounter wildlife up close.”