December 2016 - Hibernation
It is the time of year when wildlife has to survive through the cold of winter, when food is scarce or of little energy value. Some animals, such as squirrels and wood mice, lay down stores of food during the summer so that they can feed during the winter months. On warmer days during winter you often see squirrels digging up nuts buried in the summer. These animals do not truly hibernate.
Cold blooded animals, e.g. newts, frogs, toads and snakes will go into extended periods of deep sleep or torpor during winter, slowing their metabolic rates to conserve energy. Some amphibians may hibernate in the mud at the bottom of ponds whilst others together with reptiles, such as grass snakes, may hibernate in wood piles or compost heaps. They should only waken during the prolonged warmer days of spring. Prolonged warm spells in winter may have disastrous effects on their survival as they waken from hibernation too soon and are unequipped to deal with the inevitable returning cold.
Warm blooded animals such as hedgehogs lower their body temperatures as well as metabolic rates, thus conserving the fat reserves which they build up during the warmer months. Bats hibernate in areas that remain at constant temperature through the winter such as caves, hollow trees and lofts and they may congregate in significant numbers.
Adult Insects may hibernate in out-buildings, wood stores, and deep vegetation. Any which come into our homes may not be well off in the cosier environment and, unable to hibernate properly and with no food sources, are most likely to die. Some occupants of properties in the village have reported butterflies, such as Small Tortoiseshells, coming in to hibernate in their homes, hiding in nooks and crannies and behind furniture. It is best to remove them to unheated outside sheds where they will have a greater likelihood of survival. Brimstone butterflies choose dense vegetation, such as ivy, in which to over-winter. Many species of both moths and butterfly survive the winter as chrysalises, the stage between the caterpillar and the adult.
Robin - Photo with thanks to Dominic Gwilliam-Bell
Many migrating birds fly into Norfolk in the spring, e.g. swallows and house martins and since they feed on insects they leave in autumn when food supplies start to decrease. Birds which do not migrate e.g. blackbirds, robins, tits and finches to name but a few, may have to adapt their food sources, and many rely on the food which is put out by garden owners. Some birds migrate to Britain for the winter, i.e. fieldfares. These are often seen eating leftover fruit in our gardens. They will leave again in spring.
All wild creatures have different stories of survival during winter.
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