In the UK, hedgehogs typically come out of hibernation between March and May. There is a lot of variation between years, between different areas of the country and between different individuals. Emerging from hibernation is a dangerous moment in the hedgehog year. In this article, we will look at the process in more detail and understand how we can help.
When do Hedgehogs Come Out of Hibernation?
We know from observation that hedgehogs usually come out of hibernation between March and May in the UK. But why do they appear when they do? What is it that gets them out of bed in the spring?
Why do Hedgehogs Come Out of Hibernation?
There has been quite a bit of research done into why hedgehogs come out of hibernation, and as a result, we have some interesting clues and theories.
The most interesting thing is that just as males and females start to hibernate at different times, they come out at different times, and seemingly for different reasons too.
Male hogs are usually the first to emerge in March, with females rousing 2 weeks to a month later. But why is this?
Well, it’s long been thought that males come out early to prepare for the mating season. They need time to build up their weight for mating, as during the rut, they have very little time to forage for food and will lose considerable amounts of weight again.
When the males emerge in March, it can often still be bitterly cold with little food around. We believe that it’s a combination of food scarcity, temperature and decreasing daylight hours which triggers hogs going into hibernation. But what can be making these male hedgehogs emerge into what are often very inhospitable conditions?
Researchers now believe that the critical factor for the males is changing daylight patterns and testosterone. Melatonin, popularly known as the sleep hormone, is produced in increasing quantities as daylight decreases. Melatonin seems to reduce testosterone levels. So testosterone levels in male hedgehogs going into hibernation have been seen to decrease, whilst levels in those emerging increase with the increased daylight hours.
How the hogs know how much daylight there is when they are deep in hibernation in a dark and sturdy nest is a bit of a mystery. But there is speculation that part of the reason they wake from time to time during hibernation is to “sample” their daylight hours.
On the other hand, females emerging seem to be much more linked to the weather and the likely availability of food.
Although male and female hogs emerge at different times, hibernation is about the same length for both sexes. Females typically go into hibernation later, needing time to get up to a good weight after breeding and raising young.
Do Hedgehogs Emerge at Different times in Different Locations?
Yes, they do. Whether it’s temperature, daylight hours, or food availability that triggers activity, hedgehogs emerge later the further North they go.
There are marked variations even within the UK, with hogs in the south of England often emerging several weeks earlier than those in the North of Scotland. In Scandinavia, hogs can hibernate for up to six months and may not appear until June.
How Do Hedgehogs Come Out Of Hibernation?
Whatever the trigger for emerging from hibernation, the actual process is a slow and stressful one.
Hedgehogs don’t just leap out of bed ready to do the minute the alarm goes off.
Some remarkable physiological changes take place when a hedgehog hibernates. For example:
The heart rate slows to less than 10 beats per minute.
- Body temperature drops from 35 degrees centigrade to less than 10.
- Breathing slows to the point that a hibernating hedgehog may only take a few breaths once an hour.
- Brain activity pretty much shuts down, apart from one small area of the hypothalamus, which stays alert to monitor vital signs and potential threats.
When a hedgehog comes out of hibernation, all of these changes must be reversed, which is a slow and energy-intensive process.
Hedgehogs must build up two types of fat reserves to survive hibernation. Whatever fat to sustain them through the winter, and brown fat to bring them out of hibernation in the spring.
The brown fat is unusual. As it is being metabolised, it produces a tremendous amount of heat, warming the hedgehog’s body between 6 and 21 degrees in an hour, depending on the air temperature.
As the body warms, other systems start to switch on, the hedgehogs’ metabolism gradually raises to normal levels, and the hog becomes active once more.
The process of becoming active can take up to 12 hours, and a newly emerged hedgehog can seem pretty dozy for a couple of days.
Is Coming Out of Hibernation Dangerous?
It certainly is. And this is why the spring is a hectic time for hedgehog rescuers.
During hibernation, UK hedgehogs will typically have lost around 25% of their body weight. So when they emerge, they urgently need to drink and eat.
If they have emerged early, in March say, or the weather takes a turn for the worst, this may not be easy.
Their general air of being wobbly and disoriented on emerging makes them vulnerable to predators. It also means that they are even more likely than usual to stumble into trouble: falling into ponds or getting themselves tangled up in things.
And finally, in the spring, we humans tend to be very active in the garden and can easily disturb a still-hibernating hog or injure a newly active one.
How Can We Help Hedgehogs Coming Out Of Hibernation?
Spring, when hedgehogs energy from hibernation, is a critical time of year when they really need our help and support.
It’s estimated that around a third of all hedgehogs die in hibernation each year. So those emerging in the spring have survived a significant challenge. The next challenge is getting back up to a good weight for the breeding season.
So how can we help them?
Food and Water
Well, the other way around, actually. When hedgehogs come out of hibernation, the first thing they look for is water.
It’s a good idea to have a dish of water out at all times, but especially important in the spring as the hedgehogs emerge from hibernation. Make sure the water is always fresh by changing it daily and scrubbing the dish out regularly. If nights are still freezing, add a little hot water from the kettle in the evenings to keep the water liquid.
Next is food. Again we would advise that you leave out a little dry hedgehog food throughout the winter for any hogs who have temporarily roused from hibernation. Once this starts to be taken regularly, add wet hedgehog food as well.
Offering food will help hedgehogs at any time, and it is particularly important for those that emerge early or during a spring cold snap.
If you don’t have a feeding station, now is a good time to buy or build one. Feeding stations give the hogs some shelter as they eat and keep other animals off the food.
Keep an eye on the hogs in your garden. Most of them will be a bit wobbly and dopey for a day or two after emerging. But if these symptoms continue, they may be unwell and need help.
Keep an eye out for hedgehogs out in the daytime, hedgehogs “asleep” on your lawn, or hedgehogs wandering around looking drunk. Any of these can be a sign of trouble, and you should take the hog in and call your local hedgehog rescue straight away.
Keep Your Garden Hedgehog Safe
Spring sees an influx of dopey, just out of hibernation hedgehogs in our gardens at precisely the time that gardeners are most busy. Thousands of hogs are injured or killed each year in garden accidents. Take some time to ensure your garden is hedgehog safe and that you are gardening in a hedgehog friendly fashion.
Check that your pond has an escape route in place for any hogs or other wildlife that might fall in.
- Check that your hedgehog highway is clear and allows hogs freedom to roam.
- Clear up any garden netting, old pots, or anything else lying around that hogs might get tangled up in.
- Be very careful before you turn your compost over. Check it with gloved hands before you drive a fork or shovel into it. Hedgehogs love to nest in compost heaps.
- Check before your strim or cut back. Long grass and undergrowth are also favourite nesting sites. Check them over with your hands or boots before you start using power tools to clear the area.
- Do not disturb nesting hedgehogs. In the spring, if you find a hedgehog nesting in the daytime, it might be asleep, or it might still be hibernating. It’s best not to disturb them. Leave that area of the garden until the hog has moved on.
Help Hedgehogs Conquer the Hibernation Challenge
With around a third of hedgehogs dying during hibernation each year, we really need to cherish those that do emerge in the spring.
Expect to see hedgehogs appearing any time from early March to early May. If we keep a look out for this year’s prickly visitors, we can give them the help they need to survive and thrive through another year.
We hope you’ve found this article interesting and useful. Do you have a question or suggestion? We’d love to hear from you. Leave us a comment below.