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Hedgehogs

The hedgehog native to Britain is the European hedgehog (Erinaceus europaeus) which is usually found in hedgerows, farmland, woodland, and urban environments. They are usually around 200-300 mm long with a fairly long snout covered in whisker-like hairs, small black/brown eyes that protrude slightly and small ears. The four feet each have five toes, each with a sharp claw & several toughened pads of skin.

As they have loose skin they can squeeze through small gaps in fences, under sheds etc. The skin is covered with around 3500 spines by the time they are weaned, and an adult hedgehog can have as many as 7000 spines. A single spine can support the whole weight of a hedgehog and they also act as shock absorbers. If the hedgehog feels threatened the spines become erect and if danger remains the hedgehog will roll up into a ball.

During the year they are active for approximately eight months between April and November and hibernate during the colder winter months, but with global warming, this pattern of hibernation is changing. Normal hibernation is affected by various environmental and hormonal cues, with cold and lack of food shown to be important triggers. In nature hedgehogs in severe climates hibernate for long periods while those in mild climates (e.g., parts of New Zealand) may not hibernate at all. By the time the hedgehog is ready to hibernate 30% of the body weight will be fat, both brown & white. The white fat, which can account for a third of body weight just before hibernation, provides the constant energy supply to fuel metabolism during hibernation while brown fat is most important for heat generation during arousals from hibernation. To survive through hibernation, it is essential that hedgehogs develop sufficient white fat reserves to fuel many weeks and sufficient brown fat reserves for several periods of arousal. Use of fat reserves during hibernation leads to a significant reduction in hedgehog body weight over winter; values from European studies reveal total weight loss in the order of 25-40%.

During the hibernation period there are times of activity, so it is a good idea to leave food and water for these occasions. If the temperature falls below 1°C hedgehogs can get frostbite or even freeze solid, and it is thought that these periods of arousal may help to prevent them from freezing to death. Arousal after hibernation is induced by increased daylight hours and increased ambient temperatures. Males tend to come out of hibernation before females possibly because they will feed & be ready to mate as soon as the females become active or there is less competition for food. Generally, early litters have a better chance of survival than late litters and this may be a trigger for the male hedgehogs to be ready to mate as soon as the females come out of hibernation.

hedgehog

The hedgehog will virtually eat anything in the wild and are therefore omnivores, but insects, particularly beetles and caterpillars make up most of their diet. The hedgehog is a nocturnal mammal and can consume up to 20% of their body weight in a single night covering a range of a couple of Kilometres, a lot for little legs!

The European hedgehog is now listed as vulnerable to extinction in the United Kingdom and an increase in the publicity of their plight has led to an increase in complementary feeding by the general public. However, this can lead to further problems for the animal if they are fed inappropriate foodstuffs. Metabolic Bone Disease (MBD), obesity with associated cardiovascular disorders, and fatty liver disease are nutritional disorders that have been reported in hedgehogs fed improper diets.

hedgehog
Hedgehog

MBD is a broad term used to describe disorders of the bone including osteoporosis, osteomalacia (softening & weakening of the bone that become easily fractured), and rickets (deformed bones). All are very painful, and, although there are implications such as genetics and disease pathologies, in many instances it is caused by an improper diet. The disease has been seen in amphibians, reptiles, birds and mammals, and the common factor is an alteration in blood calcium levels often brought about by foods containing high levels of phosphorous, also called phosphate. Calcium levels in the body are strictly controlled by homeostatic mechanisms that involve calcium, phosphorus, parathyroid hormone, Vitamin D and calcitonin levels in the body. A proper diet is essential to maintain these feedback control mechanisms to maintain a proper calcium level in the blood. 99% of calcium in the body is stored in bone to keep the bones strong and healthy, the remaining 1% is found within intracellular fluid (fluid within cells) and extracellular fluids (blood, lymph, interstitial).

An important part of maintaining a stable calcium level in the blood is to maintain correct phosphorus levels as calcium and phosphorus have an inverse relationship i.e., an increase in phosphorus decreases calcium levels and vice a versa. Homeostatic control can usually deal with any fluctuations in the calcium to phosphorus ratio in the blood, but if there are persistent and chronically high levels of phosphorus then this control is ineffectual and as a result calcium is drawn out of the bones to compensate and leads to MBD. The ideal ratio of calcium to phosphorus in the European hedgehog is 2:1 with a minimum ratio of 1:1, and the diet should be modified to minimise or exclude foods that contain high levels of phosphorus that may lead to an alteration of blood calcium levels. All of brambles hedgehog foods are within the safe range of calcium to phosphorous ratios.

It is therefore important not to feed them with high phosphorous foods such as mealworms, sunflower hearts, and peanuts. Website searches of commercially available mealworms showed suppliers selling mealworms with calcium to phosphorous ratios of between 1:7 and 1:25! Foods such as peanuts and sunflower hearts have 1:6 and 1:7 calcium to phosphorus ratios respectively. Unfortunately, if these foodstuffs are included freely in a mix, or blend, of foods hedgehogs tend to pick out the mealworms, peanuts and sunflower hearts and then not eat the other components in the food. It can then be very difficult to wean them off these bad dietary habits when healthy nutritional food is offered but they will eat the good food if you persevere! In addition, peanuts can become stuck in the jaws of a hedgehog which can then prevent them from feeding and ultimately, they will then starve to death.

Calciworms, also called Black Soldier Fly, have more recently been added to some hedgehog foods presumably to counteract the effect of mealworms. As their name suggests calciworms have high amounts of calcium in and if these are eaten to excess can cause even more problems than mealworms! The very high levels of calcium in these can cause elevated blood calcium levels (hypercalcaemia) and this can affect many different tissues, but the effects are often most pronounced on the heart, kidneys, GI tract, skeletal muscle, and nervous tissue.  The severity of the clinical signs not only depends on the severity of the hypercalcemia, but also on the speed of development often with fatal results.

Hedgehog
hedgehog

Other problem ingredients for hedgehogs are sugar and high fat foods. The hedgehog has a high metabolic rate that is geared to the digestion of high protein invertebrates and as a result fatty foods can result in obesity and fatty liver disease that can quickly become life threatening. A food with a fat content of below 15% is usually considered to be suitable for the European hedgehog. Sugar is not part of the natural diet of any wild animal and, as in humans, can cause dental issues, obesity, and cardiovascular issues. Milk that has traditionally been given to hedgehogs in years gone by is also unsuitable as the animal lacks the enzyme lactase and therefore cannot digest the milk and can result in gastro-intestinal problems and diarrhoea. In addition, as a rule hedgehogs should not be given peanuts or grains freely within a food as these may become lodged in the gums or oral cavity causing dental problems and/or choking that may prevent the hedgehog from being able to feed properly. Bread offers little nutritional benefit for hedgehogs and should also be avoided.

It has also been suggested that fish should not be given to hedgehogs as some wildlife rescues report gastro-intestinal issues when food containing fish is given. However, there are also many rescues that say fish in a food is okay. Feeding them a reputable commercial hedgehog, such as Brambles Crunchy, Semi-moist and Meaty Hedgehog Food is recommended as the main ingredient is poultry and this is a very good source of low-fat protein, is well tolerated by the digestive system, and has many nutritional benefits to the animals.

hedgehog
Hedgehog

As the plight of the hedgehog is in very serious trouble in the UK it is encouraging that the public has stepped in to complement the diet of the hedgehog. However, there are many hedgehogs’ foods available in the market that do contain harmful ingredients such as mealworms (and other insects), peanuts, sunflower hearts, and sugar. It is important that food being fed to hedgehogs is nutritionally balanced and provides vitamins and minerals that are beneficial to the animal, even for a complementary food. For example, Vitamin D3 is an important additive as it increases calcium absorption in the gastro-intestinal tract. We do need to encourage the public to carry on feeding hedgehogs, but it is extremely important that they are also made aware of harmful ingredients that should not be fed to hedgehogs. It is important for people to check ingredients as some brands do contain ingredients that are best avoided.

Brambles hedgehog foods are all 100% safe for hedgehogs to eat and contain the correct ratios of calcium to phosphorous as well as offering great nutritional benefits to the animal.

To help hedgehogs in the garden, encourage a safe passage to and from your garden and your neighbours by creating a small hole of around 13cm at the base of fences and borders. This will help the hedgehogs to avoid roads and hence cars that are a major cause of mortality.
Leaving a quiet area of your garden uncultivated, or having a pile of logs, can give hedgehogs a safe haven, and avoiding the use of chemicals such as slug pellets and pesticides. If hedgehogs eat insects that have been in contact with chemicals such as these it can be fatal.

Specific hedgehog houses can be purchased, if you have one place it in a quiet and shady area of your garden.
Always check the borders of your garden before using a strimmer, lawn mower or gardening tools, to ensure no hedgehogs are resting there. A hedgehog nest can be very hard to notice as can be seen in the photo from Happy Hogs Hedgehog Rescue

Hedgehog hiding

If you have a pond in your garden, make sure there is a way out for any hedgehogs that inadvertently fall in. Although hedgehogs are good swimmers if they can’t get out of the pond they will eventually tire and drown so a few partially submerged rocks around the edges of the pond or a ramp will help them to climb out.

To a hedgehog a bonfire looks like a lovely place to sleep. If you make a bonfire, try to relocate it on the day you are setting fire to it, or make it on the same day. If these are not possible, please do check very carefully for hedgehogs and other wildlife before setting fire to the bonfire.

Hedgehogs hibernate during very cold spells, generally between November and mid-March although milder weather over recent years means they are often still quite active, and it is good to leave food and water out during the winter months. Brambles Crunchy Hedgehog Food is perfect for this time of year, along with fresh water.

Found a sick, injured, or orphaned hedgehog?

Visit https://directory.helpwildlife.co.uk/ to find your local Rescue whom you can ask advice from.