By Annie Hill
The original article in Russell Lights | Ngā Mārama o Kororāreka

Those of us brought up in Great Britain learned to love hedgehogs when we were children because they often appeared in our books anthropomorphised into attractive personalities. Most people have a soft spot for these endearing little animals snuffling around in gardens, looking for a hearty meal of insects and arthropods, birds’ eggs, baby birds on the ground, lizards…

Hedgehogs are serious carnivores and while they will drink the bowl of milk so many people fondly put out for them, they would much prefer a plate of cat food.

One of our never-to-be-sufficiently-cursed Acclimatisation Societies—in Canterbury—was responsible for the first introduction of hedgehogs to Aotearoa New Zealand back in 1870; the population was added to on at least another four occasions.

The idea was they would control garden pests such as slugs, snails and grass grubs, and they flourished in their new home—so much so that in the 1920s, hedgehogs were blamed for reducing the tally of small game birds and a bounty was put on their noses.

Their introduction was yet another great idea that proved less so in practice.

Although their numbers have fallen, possibly due to insecticides which destroy so many of our invertebrates, hedgehogs are still more numerous here than in Britain where their population decline is a cause of great concern.

They can be found pretty well everywhere here, apart from inhospitable environments such as above the permanent snow line and in the wettest parts of Fiordland.

Our hedgehogs are generally not as large as those in Britain, probably because they have adapted to the warmer climate by not having to hibernate for six months. Even where they do, in central and southern New Zealand, they only hibernate about three months of the year.

They are generally solitary animals and the female takes a lot of courting, with only one in ten attempts ending in mating. They mate multiple times and the successful male ‛plugs’ the female’s vagina with his sperm, safeguarding his progeny. (Moles and kangaroos do the same thing.)

The hedgehog is another animal that can delay her pregnancy if conditions are unsuitable for having babies. She can give birth to up to ten hoglets, but usually has four or five. Occasionally they will have two litters. In Northland, they probably get enough food to fatten up before food supplies are reduced in winter; further south, the hoglets would need an unusually mild autumn to survive.

Hedgehogs have a voracious appetite for creepy crawlies and can consume an astonishing volume in one night.

They also eat—critically in New Zealand—birds’ eggs and chicks, reptiles, and amphibians. They are accelerating the decline of our native wading birds, have probably already contributed to the decline and extinction of up to fifteen bird species, and are a threat to those that remain.

Even at relatively low densities of six individuals per sq km, on river braids they can cause significant losses to ground-nesting bird colonies. One hedgehog led to an entire colony of endangered, black-fronted terns abandoning their nests.

Information from their gut contents, along with camera footage, shows them hoovering up countless endemic birds’, feasting on the offspring of banded dotterels, black-fronted terns and pied oyster catchers. Our critically endangered kakī / black stilt struggles to survive in the wild, partly due to hedgehogs overrunning their habitat.

Hedgehogs have been recorded happily foraging at 2,000 metres above sea level, and are able swimmers, recorded as having covered 800m in a night, happily shoving off across a lake or river if they can smell food on the other side.

They are also surprisingly good at climbing fences and scrambling over rocks. Hedgehogs have large ranges of up to 20 hectares, but are not territorial. They travel one-two km per night, and have a voracious appetite for invertebrates, eating about 160g a day.

They take many local endemic species, such as the rare giant native centipede, wētā, native grasshoppers and other rare insects, and native snails, including the giant Powelliphanta. One hedgehog was found with 283 wētā legs in its stomach, approximately 47 wētā.

They also pose a threat to endangered native skinks, especially in cooler weather when the reptiles are less active, and are known to take frogs.

Indeed, they pose one of the greatest threats to our unique and threatened ecosystems, not in the least because few animals will take them on—even a feral dog or cat would think twice about tackling a hedgehog.

You can see why some conservationists call them hedge-devils!

Alas, benign snuffly little Mrs Tiggy-Winkle turns out to be an insatiable predator, with a taste for too many of our unique animals.