10:41am Thursday 18th February 2010
The heavy snow and cold weather we have been experiencing this winter have come as something of a surprise to many of us. We have become used to mild temperatures and sometimes heavy rainfalls, but a fortnight of snow is something that many only remember from their childhood.
Extreme cold causes living things all sorts of problems.
Freezing temperatures turn water into ice so that animals cannot drink, and plants cannot take up water through their roots.
However, the wildlife that lives in, or visits, the British Isles is well adapted to low temperatures and a shortage of food.
Many species are descendants of the survivors of the last Ice Age. And they also managed to get through the ‘Little Ice Age’ that spanned the 16th to 19th centuries, when even the River Thames would famously freeze over regularly.
So, is this recent spell of cold weather really a threat to them?
When viewed on its own it would seem not to be a problem, but in the context of the erratic weather conditions that we have seen over recent years. a more sinister picture emerges.
Think back to the summer floods of 2006 and 2007, or the scorcher of 2003, and you realise that wildlife is increasingly and rapidly facing unpredictable conditions.
Conditions that are forcing it to change survival techniques developed over thousands of years.
Some animals cannot find enough food during the winter months to sustain them, so they slow their body processes to almost a standstill to survive — a process called hibernation.
The hedgehog, pictured right, is perhaps the most well-known hibernator in Britain. It fattens up on slugs, snails and other minibeasts in the autumn, and spends the cold months curled up in a sleep-like state in a cosy nest of leaves and dry grass.
Other mammals, such as bats and dormice, also rely on hibernation to survive the winter.
But hibernating animals do not stay asleep all through the winter; they will wake up on warmer days and look for food or water. They will also wake up if the temperature drops too low, and start shivering in order to keep their body from freezing.
Every time they wake up, they use a great deal of energy which makes it more difficult to survive when food supplies are low, especially if the warm spell is followed by a particularly deep freeze, like the one we have recently experienced.
Debbie Lewis, reserves ecology manager at BBOWT, said: “The effects of the changing weather patterns can cause additional stress on hedgehog populations that are already affected by loss of habitat due to intensive farming and urban development.
“Many of our reserves may look a little scruffy round the edges in the winter, but these areas have been specifically left with tall vegetation and piles of old wood so that they can provide a great location for hedgehogs to snuggle up in during the winter.”
Cold-blooded animals have developed other ways of survival. Some invertebrates release chemicals into their body fluids which prevent them from freezing, similar to the way anti-freeze works in the radiator of a car. Many caterpillars, some butterflies, slugs, snails, queen wasps and bumblebees spend the winter in this way.
Bumblebees typify the dangers that changing climate conditions pose to wildlife that uses this winter survival technique. Wild bumblebees can be found well into the Arctic Circle and they are able to fly and look for food in lower temperatures than honey bees.
The queen is capable of founding a whole new colony and she is the only one that survives through the winter. If periods of unseasonably mild weather cause her to come out of her dormant state too early, a subsequent cold spell could be devastating for the precious cargo of eggs, thus destroying a potential new colony.
It will take wildlife a long time to adapt to changing conditions, and ironically the changing weather patterns can produce some positive effects.
A particularly warm or wet winter, for example, could result in a wealth of slugs or insects, a vital source of food for many animals. But a return to cold weather could bring with it further problems.
There are two ways in which we can help wildlife cope with these erratic changes in weather patterns, by tackling the cause of the problem and by helping to alleviate its symptoms.
The cause of the problem is well known. There is now ample scientific evidence that changes in weather patterns are closely linked to climate change and the corresponding rise in greenhouse gases caused by human activity.
So, reducing your own carbon footprint is a first step in helping stabilise climate.
The second part of the solution is to keep protecting our best wildlife habitats and species, and to minimise other sources of damage so that there is the maximum diversity as we go into an uncertain future.
BBOWT manages its reserves to include a diversity of habitat structure, which includes graded woodland edges, scrub patches, tall herbs and short turf.
This creates varied habitats and niches for wildlife to thrive in, as well as safe havens from the weather and predators, and areas rich with food sources.
Matt Jackson, head of policy, planning and wider countryside at BBOWT, said: “We are already seeing the effects of a changing climate with new species arriving on nature reserves and others struggling to cope with changes in food supply.
“The real worry is the rate of change. We need to do anything we can to slow down how rapidly our climate changes to give habitats and species as much time as possible to adapt, and as much space as possible to do it in.”
The cold snap might not have hurt wildlife as much as we thought, but it is a sign of greater changes in climate conditions that could have a devastating effect on our local wildlife.
To find out more about how to join or volunteer for BBOWT go to www.bbowt.org.uk
Picture: Mike Taylor/ www.seeing.org