March and early April in Ireland is when hedgehogs stir from hibernation. A growing fear among conservationists here is that fewer are coming out each passing year.
Numbers are hazy. “They’re probably in decline here, because they’ve declined everywhere else,” says Elaine O’Riordan, whose PhD research at University of Galway investigates Irish hedgehogs. “We’re facing the same environmental problems as Britain, France and Scandinavia.”
European hedgehogs shuffled into trouble, barely noticed, with a 30 per cent decline in 10 years. In 2024, the once abundant mammal moved from “least concern” to “near threatened” in conservation rankings.
The UK has documented a very severe decline in hedgehogs, with an estimated loss of three out of four from rural areas since the turn of the century. The same may be true in Ireland, but we don’t have numbers now or historic numbers for comparison. O’Riordan is trying to fill in some gaps.
RM Block
Habitat loss is a big problem. “The clue is in the name. They like hedges,” says O’Riordan. “When shrubby, scrubby areas and hedges are taken away, their habitat is gone.”
Hedgehogs have adapted to suburbia, especially locations with plentiful green gardens, parks and green areas. As nocturnal animals, hedgehogs can live close to people without notice. People can be surprised to find hedgehogs living in the middle of Galway city.
Sophie Rasmussen, a leading expert on hedgehogs at the University of Copenhagen, recently gave a talk in Trinity College Dublin when she visited for an Irish hedgehog crisis meeting.
In Denmark she has ginned up interest through a national hedgehog campaign, visiting schools and clubs interested in helping local hedgehogs.
“The battle to save hedgehogs is going to take place in our own backyards, in gardens, because that is where they live nowadays,” she says.
During her visit, Rasmussen met Amy Haigh of University College Cork, O’Riordan and others to set up Hedgehog Conservation Ireland and plan the battle ahead for hedgehogs.
“We’ve made life really hard for them with the loss of hedgerows and intensification of agriculture,” says Rasmussen.
In Denmark, hedgehogs living in residential areas routinely visit 10 to 14 gardens, often following a similar route each night.
They construct nests from leaves, using brambles, brushwood and other structures for support, but will nest under sheds or man-made hedgehog houses. Irish hogs are similar.
The only significant Irish research on this mammal, however, was a PhD project completed by Haigh in 2011. She followed a population of hedgehogs in a farming area outside Bandon in Co Cork for three years, catching and tagging 23 animals.
During the summer breeding season, her hogs roamed pastures and mature gardens. She saw them using small parcels of arable land too, which was a surprise as arable can be something of a wildlife desert. But the hedgerows were not intensively chopped back.
“It was allowed to flower and fruit and it had a bramble understorey, which was really important for them to build their nests,” says Haigh.
Typically hedgehogs switch between a handful of nests during the summer. The females outside Bandon ranged around 16 hectares in total, with males stepping out for females ranging 32 hectares. This increased the risk that they would meet their nemesis – the car.
Kildare Wildlife Rescue took in about 500 injured hedgehogs last year. “We are seeing less of them every year. A couple of years ago we might have seen 700,” says Dan Donoher at the rescue centre.
One problem is the use of pesticides in field crops. In a study of more than 100 hedgehogs in Denmark, Rasmussen found that nine out of 10 had pesticides in their body. About 83 per cent of them had rat poison in their liver.
“Sometimes the poison smells like honey and they will eat it,” she explains. “If they come across a dead mouse or rat that was poisoned, they may eat that.” The pesticides reduce their insect food and probably take a toll on their own health too.
Still, hedgehogs have a superpower, beyond their prickles. “They’re such loved animals,” says Haigh. “People feel an affinity to them because they are an animal you can get quite close to.”
Hedgehogs tend to stay local and are repeat visitors to gardens or green areas. “Everybody loves hedgehogs,” says Rasmussen, who earned the nickname Dr Hedgehog (Dr Pindsvin in Danish) in her home country.
There is plenty people can do to help them. Having native plants will attract hedgehog prey.
“In Denmark, we have this concept called wild on purpose. We are not messy or lazy. We’re letting the garden go a little wild,” says Rasmussen.
[ Why are hedgehogs on the move at all times of day and night?Opens in new window ]
People might let a small corner of their garden go wild but it is also crucial to allow them entry. “We recommend people put in a hedgehog highway,” says Donoher.
This means putting a gap or hole in a fence or wall of just 13 by 13cm – the width of a CD – to allow them to roam around at night. When she rented in Oxford, Rasmussen unscrewed a board in the fence so there was a gap (and put it back when leaving).
“If a hedgehog’s territory gets larger, they have a better chance of survival,” says Donoher. Another way to help them is to provide hedgehog houses.
In winter, hedgehogs can be vulnerable to hungry foxes digging them out. When active, they are occasionally hunted by badgers. But dogs off leash probably take a greater toll.
“Just one small puncture wound can get infected and can kill a hedgehog,” Rasmussen says. The oldest Danish animal that she examined was 16 years old before it died from an infected dog bite.
Some dogs tolerate them and hedgehogs can live in gardens with dogs. Kildare Wildlife Rescue mostly gets juveniles injured by dogs since their spines are not as protective as in adults.
However, most injuries seen by the rescue centre are caused by gardening accidents, especially someone using a strimmer to cut long grass or tidy under a hedge without checking what’s there. It doesn’t help that a hedgehog’s natural instinct is to curl up and stay still.
“They get some horrific injuries from strimming. Members of the public are often quite upset when that’s happened,” says Donoher. “We’ll do everything we can to save them and put them back into the wild.”
Robotic lawnmowers can also wound them. Rasmussen has worked with mower manufacturers so that they can detect and avoid them – she brings along a 3D printed hedgehog crash test dummy. Increased road traffic hasn’t helped. Cars kill one out of three hedgehogs a year
Hedgehogs are omnivores, and will eat carrion or small animals if they can catch them. They regularly snack on beetles, caterpillars, millipedes, worms and small slugs, making them popular with gardeners. They will chomp on dog or cat food if they come across it and some might be cheeky enough to enter houses through cat flaps.
Hedgehog behaviour can surprise people. They are constantly on the lookout for food and will eat birds’ eggs, mice, frogs or anything else they can grab.
“They look so cute, but they are also ferocious predators,” says Rasmussen. “I’ve seen them attack birds, including adult pigeons, and winning.”
Those who want to be a Hedgehog Hero can sign up to the mailing list at hedgehogsireland.com. Information material and various initiatives are being prepared by the group. Hedgehog sightings can be reported to Biodiversity Ireland at https://biodiversityireland.ie/surveys/irish-hedgehog-survey/.
