A rare European duck whose habitat is changing because of global warming is doing twice as well in conservation areas protected by the EU, research has shown.

But more needs to be done to safeguard the smew, a seldom seen but striking winter visitor to the UK, say experts.

Smew drakes are instantly recognisable by their dramatic black and white plumage.

The duck has been spreading northwards across Europe as temperatures rise. A study of wetland data shows that nearly a third of the birds now spend winter in north-east Europe, compared with just 6% two decades ago.

In that region, smew populations have grown twice as fast within Special Protection Areas established under the EU Birds Directive.

Richard Hearn, head of species monitoring at the Wildfowl & Wetlands Trust (WWT), said: "The EU's network of protected areas is obviously helping smew adapt to climate change, but in this newly occupied region there aren't enough of them and that could constrict the population as they spread north.

"Most Special Protection Areas were designated around 20 years ago using the data that we had then. Things have changed dramatically in the natural world since then and we need to respond to help ensure that smew and other waterbirds remain well protected."

In the UK, a small population of less than 200 smew can be found wintering in favoured gravel pits and reservoirs in lowland England.

This population has roughly halved in size since the late 1990s.

The international study led by Diego Pavon-Jordan, from the Finnish Museum of Natural History, is published in the journal Diversity and Distributions.

Protected areas still need to be maintained at the southern end of the bird's range so they have somewhere to retreat to during particularly harsh winters, say the authors.

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