There is some mention of dominance hierarchies among captive hedgehogs in early literature, but the changeability of any ‘pecking order’ suggests it is probably more individual levels of aggression between animals than each knowing its place. Indeed, temperaments vary significantly between individuals. Where fights occur, they often involve each individual lowering its head, raising its spines and butting each other’s sides, while making aggressive snorting, grunting or clucking noises. Hedgehogs are commonly found with minor wounds to their flanks and face, which are probably largely attributable to fights with conspecifics.
In an article to The London Naturalist in 1958, Miss D.A. Rook described an aggressive encounter between hedgehogs that she witnessed in her garden in the outer London suburbs on the evening of 27th July 1957. Rook described watching two hedgehogs circling each other near her garden path in what appeared to be courtship behaviour. Rook, referring to these as hedgehogs “No.1” and “No. 2”, wrote:
“While I watched, another hedgehog emerged from the north-eastern hedge, rushed at No. 1, struck it in the side and bowled it over. No. 1 instantly curled up and remained still, while No. 3 took its place in the ritual, which proceeded as before. … While No. 1 slowly uncurled and trotted off towards the south-western hedge, No. 4 came out of the north-eastern hedge and attacked No. 3. This animal, however, held its ground. … The attacker pushed its snout under the flank of its victim and heaved, evidently the intention being to roll it over. … In this instance the opportunity did not arise and No. 5 appeared from the same direction and attacked and bowled over No. 4, after which it proceeded to overturn No. 3.”
In this case, Rook may have born witness to four males fighting each other for the attention of a female.
More recently, trailcams (remote cameras that fire when a sensor is tripped and are capable of filming and photographing during the night using infrared light) have allowed many wildlife enthusiasts to find out what’s happening in their gardens while they’re tucked up in bed. Many gardeners have created a feeding station, where food is left out for visiting wildlife, and hedgehogs are a popular subject. In recent years, some videos showing very aggressive encounters have surfaced. There are a limited number of conclusions that can be drawn from these observations because it is difficult to know whether they have arisen in an artificial situation, but they do indicate that certain individuals may be very aggressive towards others.
The Metro recently posted a composite of trailcam footage on their Facebook newsfeed showing aggressive encounters between hedgehogs feeding in gardens, including one pushing another into a garden pond, and deer biologist Arnold Cooke sent me one (above) showing a hedgehog entering the frame at speed and barrelling into another, pushing it down a sloping path in his Cambridgeshire garden. Also, in 2013, Flickr user Milgy posted a video of two hedgehogs aggressively barging/pushing each other in her garden, while Tero Laakso observed two hedgehogs fighting akin to rutting deer in his garden in Finland during June 2017. Other examples include two hedgehogs fighting ferociously in Robin Cannell's garden, two hedgehog shoving one another over catfood in Alex Little's garden, one hedgehog defending a food pile from at least two others and a very aggressive fight between two hogs over a feeding station captured on Roeleke's trailcam. The common denominator in all cases appears to have been the presence of a rich food source that's apparently worth defending.
The most prolonged aggressive encounter I have come across was an attack filmed by Sudi Chiang at the feeding station in her garden in St. Peter on Jersey during April 2016. The video (above) and shows two evenly matched individuals pushing and biting each other, with one seizing the neck of the other and shaking it like a dog with a blanket. The video is edited ‘highlights’ and whole interaction lasted for about 15 minutes with repeated bouts of aggression. Sudi has recorded this behaviour several times, although it is not possible to say from the videos whether the same individuals are involved on each occasion. Similar shaking behaviour can be seen in several of the videos above.
We don't know how common these aggressive encounters are as there are very few records outside of gardens. It may be that high concentrations of food, typically one or two large bowls filled with mealworms or peanuts, bring hedgehogs into closer contact than they might normally come; the result being more aggressive encounters. Certainly, my experience suggests that simultaneous sharing of food bowls is more likely among females than either males or between males and females. I've seen several photos of multiple hedgehogs sharing a bowl—Odian Samson on Jersey photographed five individuals sharing a bowl of biscuits, for example—but I suspect these to be a mother and well-grown hoglets. Whether siblings tolerate sharing food in adulthood remains, to the best of my knowledge, unknown. Regardless, if concentrated food resources precipitate aggression, scattering the food on the lawn or spacing a greater number of smaller bowls out around the garden may help reduce fighting. Sudi's video does, nonetheless, parallel descriptions by some early naturalists in related hedgehog species, particularly during spring. Sergej Ognev, in his 1962 Mammals of Eastern Europe and Northern Asia, recounts the observations of fellow Russian naturalist Konstantin Satunin who, in March 1895, witnessed a fight between two captive E. roumanicus:
“The animal which succeeded in so grasping its opponent held it for a long time, furiously dragging it about from place to place.”
It is not just other hedgehogs to whom aggression may be directed. Farplace Wildlife Rescue owner Jan Edwards told me about a hoglet they admitted that bit the care team several times in the three days it was at the centre. Jan recalled:
“We had a very tiny baby hedgehog who would run at us and bite, drawing blood, whilst growling…. it must have been max 10 weeks old.”
Similarly, in his 1969 book The Hedgehog, Maurice Burton described an encounter between his boxer-cross and a hedgehog in a larch plantation:
“Meanwhile, the hedgehog, far from rolling up or even freezing, continued to advance, although slowly, making a cry like a ‘churr’ of a squirrel, but louder and harsher. The sounds were unnerving to the human ear and apparently the dog found them so, as well. An in the end the hedgehog merely walked away, the dog making no attempt to follow. In this instance there could be no doubt that the tones were defiant and aggressive.”
Female hedgehogs typically ignore other sows, although they will snort at one another and I've observed the occasional accompanying “side barge”, particularly when one is significantly larger than the other. Indeed, we have observed a large sow push and shove a small hog (~2 months old) on several occasions in late August/early September, which we suspect may be associated with the larger hog being pregnant. In common with many mammals, however, sows do not appear to exhibit anywhere near the level of aggression seen in males. Similarly, I have never observed, nor come across reports of, males acting aggressively towards females.
Finally, on rare occasions hedgehogs may be aggressive towards other species, in both a predatory and non-predatory sense. In our garden, we have seen hedgehogs displace the local cats from feeding plates, and Jeannie Cooper recently sent me some videos of the foxes and hedgehogs interacting in her garden on the east coast of Scotland. Among the videos was one of a hedgehog biting the tip of a juvenile fox's tail while it was feeding. A second video showed a hedgehog standing its ground against a curious cub. The videos are spliced together below. This is the first time I've come across reports of unprovoked hedgehog aggression directed towards anything other than another hedgehog, outside of a predation context, and would be very interested to hear from other readers who have observed it.