It’s often said that wild hedgehogs in the UK live for 2 – 3 years on average. This is true as far as it goes. But it’s really just a headline statistic, and as with so many things, the devil’s in the detail. When we look at the detail of how long hedgehogs live we\ll see a much more complex picture. And we’ll start to understand why our support for hedgehogs, particularly autumn juveniles, is so essential for the future of hedgehogs in the UK.
Note: This article deals with wild hedgehogs in Great Britain, not African Pygmy hedgehogs kept as pets.
How Long Do Hedgehogs Live?
It’s complicated. Although the average life expectancy of a wild hedgehog in the UK is 2-3 years, hedgehogs certainly aren’t old at 3 years.
But hang on, how do you even tell how old a hedgehog is? They don’t come with birth certificates, after all.
How Do You Tell How Old a Hedgehog is?
Figuring out how old hedgehogs are is the first step in calculating how long they are living for.
There are several methods, For long term studies of hedgehog populations, it’s possible to mark the hogs so that you can see how many of last years hogs are turning up the following year, and so on.
This is a bit of an imperfect method. You can’t assume that hedgehogs who don’t appear this next year have died, you could just have failed to spot them.
There are changes to membranes in the eyes as hedgehogs age, changes to cartilage in the legs and many older hogs take on a gingery tinge. But none of these is really an accurate method.
The most accurate method we have is described by Pat Morris. It involves looking at sections of the jawbones of dead hedgehogs. The bone grows each year during the spring and summer, but then growth slows and stops during hibernation. This creates a pattern of growth rings in the bone, just like those in a tree. With each ring representing a year of life. The method still isn’t perfect. Pregnancy can disrupt the growth rings, so can failure to hibernate. But this method allows us to make some reasonably accurate estimates about how long hedgehogs are living.
What is Old for a Hedgehog?
When we think about how long humans live, lots of us will think of the “Three score years and ten” or 70, quoted in the bible. So for many centuries, 70 was considered to be about how long people lived. This was the case even back in the days when the vast majority of people didn’t make it past 50. But still, 70 was seen as a good age, 70 was OLD.
So let’s start by looking at what’s old for a hedgehog.
Though the average lifespan for a hedgehog is 2-3 years, hedgehogs certainly aren’t old at 2 or 3. Pat Morris tells us that hedgehogs only start to be old at 5 years.
Hedgehogs in the UK live for an average of 2 to 3 years. Hedgehogs can live for up to 10 years, and the oldest recorded wild hedgehog was 16. One in 5 hedgehogs never make it out of the nest and as few as 30% survive their first winter. Natural causes kill many young wild animals, but hedgehogs suffer significantly from human activity too. For example, 335,000 hedgehogs die on UK roads each year.
In the UK 4 hedgehogs in 1000 make it past the age of seven, and maybe one in 10,000 makes it to 10 years old.
Morris explains that by ten years hedgehogs really are suffering the effects of old age. For example, one reason they are unlikely to survive to this age is that they will be unable to eat, with teeth worn down from years of chewing gritty food.
A study by Sophie Lund Rasmussen for the University of Southern Denmark autopsied 700 wild hedgehogs. One was found to be 16 years old, another 13 and several were aged between 9 and 11 at the time of death. And yet the average age of the 700 was only 2 years.
Wildlife online cites another study where a female European Hedgehog kept in captivity lived to be 15 years old.
So we can see that in a perfect world, our hedgehogs have the potential to live to a ripe old age. So why are we seeing such a low average life expectancy?
When Do Hedgehogs Die?
Pat Morris’ 1976 study is still the benchmark for when hedgehogs die. He found that although stillbirths in hedgehogs are relatively low at around 3%, one in five hoglets don’t make it out of the nest. He found a higher death rate amongst hoglets who were part of larger litters.
This is perhaps not surprising given the extra demands a larger litter puts on the mother.
On leaving the nest, a further 30% – 50% of hoglets will not make it to their second year.
These statistics sound shocking, but they are really not unusual for wildlife. Infancy and youth are the most dangerous and challenging times in any creature’s life. Compare the hedgehogs to, say sea turtles, where only 1 in 1,000 makes it to adulthood.
Still, when you think that hedgehogs don’t reach sexual maturity and can’t breed until their second year, its easy to see why helping more hoglets make it through their first winter could help the species.
Once they are past their first winter, things improve dramatically with the death rate declining by about 30% for each additional year of life.
But the challenges faced by hedgehogs – mostly man-made one way or another, continue to stop hedgehogs reaching old age and threaten the future of the species.
Why Do Hedgehogs Die?
The majority of wild animals don’t live into old age. The natural world presents too many dangers and challenges for that.
But along with the challenges presented by nature, hedgehogs (and every other creature on the planet) now face a whole range of life threats created by man.
Here are some of the main reasons our hedgehogs die before reaching old age.
Although hibernation is an essential strategy for hedgehog survival in colder climates, it’s also the time when most hedgehogs die.
In Sweden, Hans Kristiansson found that on average 33% of hedgehogs die during hibernation every year. The figure varies a lot depending on the climate, the weather in the preceding summer and the severity of the winter. But any way you look at it, its an alarmingly high number.
And several studies have shown that hedgehogs in New Zealand who don’t hibernate live roughly twice as long as the same species of hog in the UK and Europe who do.
So why do so many hogs die in hibernation?
This is probably the primary cause of hedgehog deaths during hibernation.
Hedgehogs lose 40 – 50% of their body weight during hibernation. Juveniles, especially those from late litters may simply fail to put on enough weight to survive the winter. Mothers too, especially those who have had a late litter, can struggle to get back up to a good weight after weaning hoglets.
But in a long cold winter, even the fittest and fattest hogs can face challenges if the hibernation period becomes extended.
A dry summer can result in a scarcity of food that may not threaten hogs whilst they are active but could cause problems come hibernation time.
Providing additional food and water for hedgehogs in our gardens can help them to survive hibernation.
Hedgehogs in hibernation are vulnerable to extreme weather events. And obviously, with climate change, these are becoming more and more frequent.
Whilst hedgehogs are good swimmers and pretty speedy runners a hibernating hedgehog stands no chance in flood.
Hedgehogs are especially vulnerable to predators during hibernation. Badgers are hedgehogs main predator in the UK. Still, there is speculation that foxes may also take hedgehogs during hibernation, though it’s unclear whether the hedgehogs they are taking are hibernating or already dead.
There’s also evidence of a phenomenon called “nibbling” which hedgehogs are found with wounds in their skin and patches of short of missing spines. This is thought to be caused when hibernating hedgehogs are pecked at by magpies or nibbled by rats or mice. Though nibbling is unlikely to cause death in itself, it can lead to a potentially fatal infection.
Hedgehog houses offer protection from larger mammals and birds but probably wouldn’t stop nibbling by rats or mice.
Hedgehogs learn how to build good, solid, well-insulated hibernacula. The attempts of juveniles hibernating for the first time can often be easily spotted.
These nests are often flimsily constructed and poorly sited affairs which are unlikely to protect the hedgehog through the winter.
We know that most hedgehog houses are occupied by young hogs during hibernation, and there can be little doubt that these will help with survival.
Natural Injuries, Illnesses and Diseases
Like any other animal, hedgehogs are subject to a range of natural illnesses, injuries and diseases, some of which can prove fatal.
Hedgehogs can pick up a range of injuries in the course of their natural lives. Legs taken off by foxes or other predators and wounds incurred during courtship and mating are some of the most common.
It has been noted that hedgehogs have a truly remarkable ability to heal. It’s not unusual to see a three-legged hedgehog wandering around, surviving perfectly well after such a severe injury.
However, when injuries become infected, this is where the trouble starts. And an untreated infection can quickly lead to serious illness and death.
Like all wild animals, hedgehogs are subject to a range of internal and external parasites.
Whilst many of these are not fatal when present at a low level, if the parasite load on an animal becomes high, it’s always a cause for concern.
For example, lungworm can quickly lead to fatality in hedgehogs if not treated.
Many ticks are often found on very sick hedgehogs, and it was thought that the ticks were causing the sickness. Some researchers are now speculating that sick hedgehogs might actually be more attractive to ticks.
Illness and Diseases.
Like humans, hedgehogs get illnesses caused by bacterial, viral and fungal infections. And like humans, these illnesses can be mild or may become more severe or even fatal.
There are other diseases which are very much hedgehog specific.
Balloon Syndrome is caused when an injury goes untreated. Gas develops and gathers under the skin, so that the hedgehog blows up, like a balloon and sometimes to the size of a football. The legs are forced out to the sides, the hedgehog can’t walk and will eventually suffocate if not treated. Luckily that treatment is reasonably simple involving removing the built-up gas with a syringe.
Pop Off is a prolapse of the orbicularis muscle which stops the hedgehog from curling up and can therefore be very dangerous. It causes the spines to ride up on the back, exposing the tail and legs. Pop off is often caused by trauma, like a hedgehog trying to tree itself when trapped. In young hogs, the muscles will usually heal themselves, but older hogs typically need medical attention.
Human Related Damage
Hedgehog rescuers report that 80% or more of hogs brought to them are injured or dying through “human-related” conditions.
It’s a horrific statistic, but thankfully something we can all help to reduce.
Let’s take a quick tour through some of the human-related issues that shorten hedgehogs lives.
A 2020 survey from Nottingham Trent University estimates that 335,000 hedgehogs may die on UK roads each year.
With the national hedgehog population standing at just 1 million this is a truly shocking figure.
Hedgehogs die on our roads because they must cross them, in the dark.
Hedgehogs need to roam between 1 and 2 miles each night to collect the food they need. Road bisect their ranges, so must be crossed.
With an ever-expanding road network, the problem is getting even worse.
But we can help with this in lots of ways. Political pressure for the inclusion of wildlife bridges and tunnels in new road schemes is one way. Support for driver education schemes is another. But perhaps the most significant way we can help is by making and encouraging hedgehog highways.
As gardens become more and more critical as hedgehog habitat, developing an extensive network of highways linking our gardens, parks and public spaces might offer the best chance of getting hedgehogs off our roads.
Though our gardens are an essential habitat for hedgehogs, they can also be hazardous, and many hedgehogs die each year through garden-related incidents. These include:
Falling into ponds. Hedgehogs can swim, and they can climb, but they can’t climb out of smooth-sided, artificial ponds, be sure to offer an escape route.
Strimmer injuries. Hedgehogs love to snuggle down in long grass and undergrowth. Be sure to check before you strim.
Bonfires. Bonfire night happens right around hedgehog hibernation time. Try to only build your bonfire on the day you are going to light it, and even then, check it over for hogs before you light the match.
Netting and litter. Hedgehogs are good at getting stuck in things. Garden netting, string and wire and stuff like tin cans or old yoghurt pots are prime suspects.
Poisoning. Hedgehogs will eat almost anything, so poisoning isn’t unusual. But hedgehogs are being poisoned by toxins getting into their systems through the invertebrates they eat too. These include pesticides, rat poison and slug pellets. Avoid all these in a wildlife-friendly garden.
Killing with Kindness. Feeding hedgehogs can make a huge contribution to their chances of survival. But the wrong food can cause illness or even death.
Foods high in phosphates interfere with the hedgehogs’ ability to process calcium and can lead to bone disease. Culprits include mealworms and peanuts.
High-fat foods like some cat food can lead to obesity and heart problems for hedgehogs who are designed for a low fat, high protein diet.
And milk can cause severe digestive issues for lactose-intolerant hedgehogs.
We have a guide to what hedgehogs eat and what you can safely feed them here.
There are of course a whole host of other problems which we humans cause for hedgehogs, for the full run down take a look at this article.
Hedgehogs – Not Living As Long As They Should
In this article, we’ve seen that although hedgehogs can live to over 10 years old, the average lifespan of UK hedgehogs is just 2 to 3 years.
Few wild animals live to old age because of the inherent dangers of the natural world. But added to those dangers, hundreds of thousands of UK hedgehogs are dying early each year from “man made” causes.
Every additional year a hedgehog lives gives it another chance to breed and strengthen the species’ survival chances.
Thankfully we can make a real difference. Each hog counts. From supporting hibernation by providing food and housing, connecting gardens with highways and avoiding poisons and toxins in the garden. There are so many things we can do. The one thing we can’t do is do nothing.
We hope you’ve found this article interesting and informative. Do you have questions or suggestions? We would love to hear them: leave us a comment below.