As winter approaches, many of us will start to wrap up warm, huddle around the fire and stay indoors to fend off freezing temperatures. But how do animals in the Royal Parks cope?
London's eight Royal Parks are home to some 4000 species but how animals adapt to cold temperatures varies. How they cope depends on a number of factors, largely their size, the type of food they eat, whether they are hot or cold blooded, and if they can fly.
During the cold weather, some birds like the barn swallow will head south to places such as South Africa, whereas species such as the black cap which have summered in eastern European countries migrate to less cold climes such as Britain.
Deer in Richmond, Bushy and Greenwich Park get a new winter coat, usually in a faded grey brown or red colour. The red and fallow deer's winter coat is thicker than their summer one and is comprised of two layers to insulate them from cold weather and snow. They also build up winter reserves in the autumn by feasting on sweet chestnuts and horse chestnuts. Visitors are therefore reminded not to remove chestnuts, or any plant or fungus from the Royal Parks.
Like many of us who would rather stay snuggled under the duvet of a morning, some animals also prefer to conserve their energy, only for them it's key to their survival. Hibernation is an extended state of inactivity which sees a dramatic drop in body temperature and heart rate. This reduces energy expenditure when food is scarce.
Only two types of mammals in the Royal Parks hibernate during the winter – hedgehogs and bats. Hedgehogs hibernate from October/November through to March/April. With hedgehog numbers declining nationwide, we are very fortunate to still have hedgehogs in four of our parks. Results from a recent study about hedgehogs in Regent's Park – the only park in central London to have retained a hedgehog population - will inform our longer-term conservation and horticulture plans.
Bats hibernate when night time temperatures drop below five degrees or so. They look for somewhere that will remain frost free, a constant temperature and humid (so they don't dehydrate), such as crevices within trees, underground sites and within buildings.
Cold-blooded animals such as frogs, toads, newts, lizards and snakes also hibernate during winter. They hide away under logs, stones and compost heaps with amphibians also burying themselves in silt or in the muddy banks of ponds. To lend a helping hand we recently installed a hibernaculum in Richmond Park to provide a refuge for snakes and lizards over winter, and across the Royal Parks we leave piles of logs and brash lying around for overwintering reptiles and amphibians.
Many adult insects die at the end of summer or autumn, leaving their eggs or pupae under plant litter, in soil, or in bark crevices during winter. The workers and males of social wasps and bumblebees will die in autumn with only the new, mated queens remaining to hibernate and emerge in spring to start a new nest.
Some butterflies, such as the small tortoiseshell and peacock, survive winter by seeking out a cool sheltered space such as an unheated room or garden shed, where they enter a state of dormancy. Other butterflies such as the painted lady or the silver Y moth prefer to avoid British winters by migrating to warmer climes.