Bad weather for bugs

Froghopper with rain drops (c) Maria Justamond via BBC Autumnwatch Flickr group What impact does wet weather have on bugs such as froghoppers?

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Whether it was a bungalow or a burrow, the second wettest year on record saw families flooded out of their homes across the country.

But for the smallest victims of 2012's extreme weather, the stakes are higher than simply insurance claims: they mean the future survival of species.

Conservationists now face an anxious wait to find out how a population of endangered Tansy beetles have fared following their relocation from the banks of the River Ouse in York due to last year's floods.

But for those with less interest in "creepy crawlies", what impact can the loss of a few invertebrates have on our wildlife as a whole?

Bad for butterflies

As president of the charity Butterfly Conservation, Sir David Attenborough warned last year that 2012 would present a struggle for many species.

Invertebrates in the rain

Common blue with water drop (c) Don Sutherland via BBC Winterwatch Flickr group

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This week the charity will release details from its annual Wider Countryside Butterfly Survey but after what they call a "washout" year, the findings could be bleak.

"Butterflies like to fly generally on nice, warm sunny days and if it's a nice, warm, sunny day they can mate and lay their eggs," says the survey's co-ordinator Dr Zoe Randle.

"Obviously if you don't get many warm sunny days, there's less opportunity for them to get out and breed."

She explains that wet weather brings a further threat to both butterflies and moths in the form of moulds, viruses and pathogens that prove fatal to the delicate insects.

According to experts, there is some anecdotal evidence of drinker moth caterpillars climbing up grass stems to avoid floodwater but only surveys can reveal the impact of the inundation.

Failing food chain

You may not have noticed the lack of butterfly and moth caterpillars but the UK's bird life certainly did.

The British Trust for Ornithology (BTO) refers to last year as "one of the worst breeding seasons on record" following poor results in its annual surveys of nests and fledglings.

Start Quote

If these conditions become more frequent, they could have long-term consequences for Britain and Ireland's bird populations”

End Quote Dr Dave Leech British Trust for Ornithology

Kestrel numbers were down and the lowest productivity rate in 50 years was recorded for chaffinches, suggesting that the heavy weather disrupted a wide variety of species.

Chicks were lost as record rainfall in April and June washed out nests and young birds had not developed the feathers to protect themselves. According to the BTO's senior research ecologist Dr Dave Leech, food was the key issue.

"A group that really suffered was the resident species that are really very dependent on caterpillars. The best examples of those are blue tits and great tits," he tells BBC Nature.

"The timing of the caterpillar peak is really vital in terms of determining their breeding success. Because it was such a bad caterpillar year in terms of the weather, there was very little food around for them."

Although Dr Leech is confident that songbird numbers can bounce back after a poor season because they have large numbers of chicks every year, he expresses concerns about a long-term change in weather patterns.

"The worry is that the extreme conditions in 2012 were the result of a shift in the position of the jet stream... If these conditions become more frequent, they could have long-term consequences for Britain and Ireland's bird populations."

Blue tit in the rain (c) David England via BBC Winterwatch Flickr group BTO surveys found blue tits fledged 13% fewer chicks than usual in 2012

You'd be forgiven for thinking wildlife living along British waterways would have a bumper year in wet weather, but it seems that there can be too much of a good thing.

Mark Robinson, ecologist at the Canal and River Trust, highlights that water-specialists such as Daubenton's bats are incredibly sensitive to changes in their environment.

"It's been particularly bad for bats because of the wet period through the breeding season with insect food being affected," he says.

"That's certainly something that will have an impact along the canals because canals are [usually] such good feeding habitat."

Moths suffered a disastrous breeding year in 2012 and, as the favourite food source of the flying mammals, this has a knock-on effect for bats.

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The Bat Conservation Trust expressed concerns for species last autumn after poor weather interrupted the essential foraging period before hibernation.

According to the charity, rare species are particularly vulnerable to disruption. Monitoring schemes in May will reveal any early indicators of how bats fared, however consequences for the long-living species may not be fully realised for years.

Year of the Slug

And it's not just the more obscure species that have a hard time during unseasonal floods. Some of our most iconic mammals suffer the from the weather's impact on invertebrates.

Badgers and hedgehogs that rely on earthworms could face hard times, according to Matt Shardlow, chief executive of the conservation charity Buglife.

Unsurprisingly, worms living in true floodplains that are frequently waterlogged are adapted to survive in these conditions. But when the ground becomes unexpectedly saturated, problems arise.

"There are about 20 different species of earthworm in Britain and some of those species are adapted to flooding," Mr Shardlow explains, but he warns that temperature is all-important.

"In warm weather in summer, three or four days [in flood water] might be enough to destroy the worm population whereas in the winter it might be weeks and they might still be reasonably ok."

Garden snail Moist molluscs such as the garden snail are wet-weather winners

"In the winter they are probably under ground already, they have probably slowed down metabolically, so they don't have the same high oxygen demand."

2012 was dubbed "the Year of the Slug" and Buglife reported bumper breeding success for molluscs, crane flies and drone flies, so it seems that not all small things do badly in a downpour.

But the poor breeding conditions for some of our beetles, butterflies and bees could have far-reaching consequences for British wildlife.

"A wildlife-rich countryside with lots of suitable habitat [that is] well connected and with strong populations of species will be able to recover from extreme weather events," says Mr Shardlow.

"But an impoverished countryside with species populations already struggling will be less able to recover and we could have local extinctions of vulnerable species."

Winterwatch continues on BBC Two at 2030 GMT until Thursday, 17 January.

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