Hedgehogs in Winter
by Hazel Roden
Hibernation is a way hedgehogs use to survive cold, dark winters without having to forage for food; they turn down their metabolisms to save energy and use their fat stores to survive. This is why a hedgehog needs to be 800g to survive hibernation and lighter weight hogs tend not to hibernate. In hibernation their heart beat falls dramatically from 190 to 20 beats per minute, body temperature drops from 35C to 10C and their respiration is reduced to one breath every few minutes. Mammals feed heavily in summer and autumn, storing fat to see them through the winter.
Not all hedgehogs hibernate – it depends on a critical temperature to trigger (usually 3c and under) and a shortage of food.
Some hedgehogs will enter torpor – where the hog conserves energy in the short term, often helping survival after a brief bout of poor conditions, such as cold nights. It usually lasts a day when an animal’s breathing, heartbeat, body temperature and metabolism are reduced.
It is worthwhile remembering the hedgehog is not asleep but in the state of hibernation and this can vary from long, deep unconsciousness to light spells of inactivity. They can wake up and move around then go back to their nest to hibernate again. It is thought they will move nests at least once during the winter.
Ways you can help hedgehogs during the winter
Provide a hibernation site that is safer from predators – a hedgehog house or a pile of logs in which they can make a nest.
Pick up discarded rubbish - hedgehogs can be injured by litter and can starve to death by getting trapped in discarded debris as they find it difficult to reverse due to their prickles.
Bonfires offer a cosy home for a hedgehog. Check, just before a fire is to be lit, by lifting the base up with broom handles (not a fork!) and shine a torch in to look (and listen) for any wildlife before lighting. After checking, light from one side only to allow an escape route for anything you may have missed.
Hedgehogs can swim but can become trapped in ponds with sheer sides. Keep water levels topped up, provide a gently sloping edge if possible or place half submerged
rocks in the water as an escape for them.
Ensure there is a bowl of water replaced daily and a bowl of dry food available at all times. Stop giving wet food.
images from The British Hedgehog Preservation Society and Igel-Cartoons V
TRUE – the British hedgehog population is in rapid decline and it is thought 50% of rural hedgehogs have disappeared since the millennium.
FALSE – hedgehogs go to sleep in winter and wake up in spring.
TRUE – there are things we can easily do now to help hedgehogs through autumn and winter.
You may have heard of The Hedgehog Highway. This is a system where sections of land, often gardens, are linked by having their boundaries made accessible to hedgehogs using ground level holes. This enables the hedgehogs to move freely through different habitats to find food, nests and a mate. It is quite common for hogs to roam 2-3km a night. Enclosed gardens reduce the diversity of food, nesting material and the opportunity to reproduce. A gap only needs to be 13cm X13cm to allow a hog through but too small for most pets. The gap could be made by cutting a small hole in the bottom of a fence, removing a brick from the base of a wall or digging a channel underneath a fence or gate. Signs can be placed near the hole to mark the purpose of the gap.
During the cold months when food is scarce, hedgehogs can drop their body temperature and go into a deep sleep or hibernation. They can reduce their heart and breathing rate so that it does not use much energy. It is a myth that hedgehogs sleep for the whole of the winter; it is likely they move nest at least one during this time. Hedgehogs will still forage for food in December and January so keep feeding them until there are no signs of them, mainly uneaten food and lack of droppings.
If there is a warmer spell of weather maybe put out some dry food such as cat or dog biscuits or muesli. Wet food will freeze. Remember to put a dish of water out daily and do not give them milk as they are lactose intolerant.
You may want to provide a hedgehog house; there are instructions to build your own on the websites given opposite. Alternatively, several places sell them online. A log pile is as good and will attract insects, beetles, snails and slugs, all super popular snacks of hedgehogs. Finally, check drains are covered as hedgehogs are not good climbers and will get distressed and stuck there. Although they do swim, they are not natural swimmers so it would be helpful to have some stones for easy access. Please check compost heaps before turning as there may just be a sleepy hog in there.