Wildlife will suffer if the current drought conditions in the southern and eastern parts of England continue into spring, some experts fear. So which animals and plants will be hit hardest if there is no significant rainfall in the next two months?"It's this time of year when the weather starts warming up and frogs start breeding - but they haven't been breeding," says John Wilkinson, research and monitoring officer at the Amphibian and Reptile Conservation Trust (ARC).
"Toads have been seen out and about, but there are no reports yet of toads breeding either."
Amphibians are just one of the groups of animals that nature observers fear may have problems reproducing this year, as groundwater levels are even lower now than in the infamously dry summer of 1976, according to the Department for Environment, Food and Rural Affairs (Defra).
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Wetlands are areas that are waterlogged for prolonged periods. They are home to many specially adapted plants and animals. In times of drought, lack of water in parts of wetland habitats means less food is available for its wildlife.The sandy, nutrient-poor soil in heathland provides good conditions for plants like heather, gorse and bracken. Heathlands are home to animals including reptiles and many species of butterflies and moths. Low rainfall can bring risk of fire to these areas, which may destroy bird nesting areas and is particularly threatening to reptiles.The diversity of flowers and grasses in wildflower meadows form an important habitat for many species of insect. Orange-tip, meadow browns and skipper butterflies lay their eggs in certain meadow plants. These habitats and the wildlife they host tend to be resilient in times of drought.During the 1976 drought, many trees died from moisture stress levels. Symptoms of drought stress include foliage wilting and browning, with affected trees being more susceptible to fungal diseases. Beech trees are potentially at risk of drought whereas oaks might fare better.According to the UK's Centre for Hydrology and Ecology the average rainfall so far this winter has been the lowest since 1972."If ponds dry up totally," says Mr Wilkinson, "you could have lots of dead tadpoles." Drier and windier conditions could also make it more difficult for juvenile amphibians to survive their journeys between wet habitats.
The ARC is also worried about the great crested newt, a protected species, which likes to make its home in large fish-free ponds. Natterjack toads, which also did poorly in the spring drought of 2011, may also be unable to complete their lifecycle.
But Peter Brotherton, the biodiversity manager for Natural England, says that "drought is part of nature's cycle", and, at present, a lot of animals, plants and insects are still in hibernation. This means that the population picture is unclear.
"However, when we get extreme events, we get animals dying," he says. "[And] what is worrying is that normally at this time of year we expect soil to be near saturation after winter."
Charlie Kitchin, the RSPB's site manager of the Nene Washes in Cambridgeshire, says the 2,000-acre wetland and grassland area is now struggling following two winters with relatively little winter rain and no flooding. One species that could suffer, he says, is the black-tailed godwit.
"There are only 50 breeding pairs in the country, and we have 40 of them, and everything is bone-dry," Mr Kitchin says.
"They have long thin bills, and the problem arises if water levels drop and they are unable to feed, they can't hold their territory and this is the area where they should be raising their young as well.
But one bad nesting season, he says, is "not the end of the world".
"One of the features of flood plains is that they're volatile anyway," he adds. "But if they fail to breed another year, the population is likely to dip again."
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Natterjack toads, which are rare in Britain, had a poor breeding season in south-east England in 2011, due to the drought last winter.It is feared their population may dip again if the drought continues this spring.They can also be found in Norfolk and Lincolnshire, along the coast between Lancashire and Dumfries.Natterjack toads are claimed to be Europe's noisiest amphibian, with the male call audible over several kilometres. He says that birds such as spotted crake, which usually turn up from Africa and are attracted to large pools of water, did not show up last year. Cranes bred successfully but birds like snipe, redshank, gargony and lapwing had their "worst year ever". "And it looks like this year could be the same too," he adds.
The lapwing nesting season is towards the end of March, and observers will be assessing their success rate towards the end of April.
While the impact on birds can take longer to become apparent, butterflies respond quickly to environmental change and it can be difficult for them to cope with any major change to their habitat.
After the 1976 drought there was a very sharp decline in some specialist butterfly species in the UK. According to the charity Butterfly Conservation, "butterflies are seen as indicator species so these serious declines may represent a wider insect biodiversity crisis".
Mr Brotherton says a lot of meadow species like butterflies die back quickly - they are "boom and bust" species and can recover quickly from a one-off drought, but it is other more established habitats that can be plagued long after a drought ends.
"Generally across habitats, certain types of trees are more susceptible, like beech in the south-east, and old, young and diseased trees," he says.
"With very old trees, like in Windsor Great Park for example, we may see some die-off there, and that impact may last for a decade afterwards.
"You may not see trees fall over for a year - the knock-on effect is when they fall on to ground vegetation.
"But species like oak and ash are more resilient to drought, and heather is also pretty resistant."
Some animals can weather a drought efficiently. John Wilkinson says that grass snakes should be able to find food easily. Bats' success will depend on how their prey species fare.
Lapwings usually begin nesting in March, but the drought could affect chick numbers There has been a lot of reported otter activity already, so it appears that they are not in any danger.
While water voles are the fastest declining mammal in the UK and vulnerable to drought, they can actually benefit from drought, as they eat plants on the water's edge.
Jeremy Biggs, director of Pond Conservation, says these plants actually need to dry out to promote germination and regrowth. This means more food for the water voles.
Mr Brotherton says the "real losers" will be freshwater and wetland species, with fish populations already struggling in places, and fish having to be moved from rivers.
With less water in the ground there are other effects on rivers too.
Mr Biggs says that without water dilution there is a higher concentration of nutrient and pollution levels in water run-off from industrial land and farmland. Sewage levels in rivers could also rise.
He says that, in fact, half of all freshwater organisms tolerate drying out, and can often bounce back the following year. "The issue is going to be whether there are more droughts to come in the following seasons," he adds.
Mr Brotherton is only too aware of this danger.
"I think that the main impacts will be in summer, not now," he says.
"Actually if it's a one-off - like 1976 - wildlife will cope pretty well.
"But if it's a sign of things to come, and this pattern repeats year on year, it really will lead to wholesale changes to Britain's wildlife."
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