Image caption Hedgehogs in urban areas can be helped by the provision of "hedgehog houses"

UK wildlife charities are asking for people's help in examining if hedgehogs are being affected by climate change.

Retired hedgehog expert Dr Pat Morris performed a study 40 years ago showing that temperature affects when the animals emerge from hibernation.

With the British Hedgehog Preservation Society and People's Trust for Endangered Species, he wants to see if warming since then has changed things.

Hedgehog numbers fell in the last 50 years, largely due to land use change.

From an estimated 30 million in the 1950s, the UK population shrank to about 1.5 million in 1995, and has almost certainly fallen further since then.

The spread of urban landscapes and industrial farming are among the factors involved; but climate change could be having an impact as well.

As a researcher at Royal Holloway, University of London in the 1970s, Dr Morris conducted a survey trying to map hedgehog populations across the country.

"We took observations of hedgehogs that people had sent in for mapping," he told BBC News.

"And later on we looked at the dates on the records - the point in the year by when people had made 50% of their observations - and we could compare records between the north and the south.

"And what we found was that the hedgehogs were being observed about three weeks later in Scotland than they were in the south - or another way of putting it is that they were emerging from hibernation three weeks earlier in the south."

Since then, the world's surface on average has warmed, and the UK is no exception, with the Central England Temperature record, for example, showing a rise of at least 0.5C in the interim.

Winds of change

This change has been found to affect species of plants, insects and birds, some of which are now flowering or breeding earlier each year, or moving into areas that were previously too cold.

The new study will show whether hedgehogs are following suit.

Even if they are, this would not necessarily be bad news for the animals.

However, Dr Morris explained, high temperatures during hibernation could be a problem - as are extremely cold periods.

"Ideally they want to hibernate just below freezing point," he said.

"A very long period with low temperatures mean fat reserves get used up more quickly in keeping the animals warm; but they also get used up more quickly if temperatures rise to 8-10C during this period, simply because chemical reactions - which metabolism basically is - proceed faster at higher temperatures."

The charities are asking people to register with the project, make observations between February and August, and submit them periodically to the same website.

Once analysed, the records can be compared with those from the 1970s. If there are enough participants, data will also be gathered in subsequent years and averaged.

The hedgehog was voted the favourite animal in England and Wales five years ago, and a plethora of initiatives has been launched to study them and raise awareness of their shrinking numbers.

The public are also able to take part in studying how climate change is impacting other species through the Nature's Calendar initiative.

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