Hedgehog » Pest Detective

About this pest

Hedgehog looking for food on the forest floor.
Hedgehog head and snout.
Hedgehog tail.
Hedgehog rolled up protectively.

KEY CLUES

Distinctive features: Nocturnal animal with a round back covered in brown and white spines. Short legs and tail, pointed snout with black nose. Often heard rustling or snuffling, before being seen.

Size: Male and females are the same size, with a body length of 150-270 mm, and an average weight of 650-700g when not hibernating.

Droppings: Droppings are black, or dark greenish, 30-50 mm long and about as thick as a pencil. Droppings are dryish and contain many insect parts.

Footprints: Central pad and five toe-pads may be obvious. Forefeet prints are wider and rounder, hindfeet prints longer and narrower. Claws may show on soft surfaces.

Kill signs: Holes in snail shells and eggs; eats invertebrates, lizards and frogs whole. Bits of birds may be left.

Vegetation damage: Eats some vegetation, but signs are not obvious.

Eye shine: Bright red and close to the ground.

Distribution: All three main islands and some offshore islands. Most common in lowland and coastal areas; prefers dry areas.

WHY ARE HEDGEHOGS PESTS?

Ecological impacts

Hedgehogs have a negative impact on New Zealand’s ecology as they eat the eggs and chicks of our native ground-dwelling birds and consume large numbers of native invertebrates.

They are proven predators of the eggs of riverbed breeding birds such as banded dotterel and black-fronted tern, and have been known to kill and eat chicks of a variety of species, up to the size of two week old chickens. Small ground-nesting species such as pipit may be particularly vulnerable. Hedgehogs have been shown to be serious predators of colonial nesting sea birds in Britain. Hedgehogs are a major predator of northern populations of New Zealand dotterel.

Hedgehogs may also have significant impacts on native slug, snail, and terrestrial insect populations. They have a voracious appetite for invertebrates on Quail Island and take many local endemic species. They are known to eat the rare giant native centipede, and rare insects in the MacKenzie Basin. They have been known to eat the native snail Wainui aurnula. Lowland populations of Powelliphanta snails may also be severely affected, particularly the Patarau and Otaki sub-species. Only smaller (juvenile) snails are eaten but this severely affects recruitment and population recovery.
Hedgehogs are likely to prey on lizards, particularly in cooler periods when lizard activity slows. Hedgehogs may also be predators of native frog species, as they are known to take introduced frogs and their range overlaps with some endemic frog species.

Other impacts

Hedgehogs are a spill-over host for Bovine Tuberculosis (Tb) but are not thought to transmit the disease i.e. TB is more likely to be found in hedgehogs inhabiting areas where the possums have TB and are at high densities. Hedgehogs often have lots of fleas, although the specific hedgehog flea didn’t make it to New Zealand. They can carry hedgehog ringworm, but rarely transmit it to humans. Hedgehogs suffer from hedgehog mange mite, which buries its eggs in the skin, creating scaly skin and scabs all over the body. The parasite blinds the hedgehog (so you often see these ones during the day) and kills large numbers of hedgehogs.

Droppings

Hedgehog droppings.
Hedgehog dropping.
Close-up detail of dried-up hedgehog dropping showing insect remains.
Hedgehog dropping in grass, with scale ruler.

Separate

Droppings are usually deposited singly, are glossy black (with a dark greenish colour for fresh droppings), 20-50 mm long and 7-10 mm wide (about the thickness of a pencil). Latrines of more than 50 droppings have been found in New Zealand. Droppings are usually are quite dry, and mostly contain tightly packed recognisable fragments of invertebrate exoskeletons such as beetle carapaces, head or body segments. However the content will depend on what they have been eating and can also include eggshell fragments, feathers and bits of lizard.

Can be confused with:
The dryness and particulate texture of hedgehog droppings, from excreting insect parts, is quite different when compared to mustelid (stoat, weasel and ferret) or cat droppings. Mustelid and cat droppings are very pointed at either end, while hedgehog droppings are relatively blunt in comparison. Mustelid droppings are usually also twisted; hedgehog dropping may be curved, but are generally not twisted. Cat droppings have segments; hedgehog droppings do not.

Southern bell frog droppings can resemble small hedgehog droppings in size (about 20mm), shape and texture, though are more brown than black in colour. See more: 'Rat or frog dropping?'

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Footprints and Tracks

Hedgehog forefoot (top) and hindfoot print.
Hedgehog footprints.
Hedgehog prints in a tracking tunnel.
Hedgehog prints in a tracking tunnel.
Partial hedgehog paw print.
Hedgehog hindfoot pads.
Hedgehog hindfeet and forefeet.
Hedgehog nest.

Paws and feet

Prints are five-toed, resembling a ferret or large rat print. Forefeet are broader and shorter in length than the hindfeet, meaning there are two distinctly different prints left by the one animal. Hindfeet prints 40-45mm long and 30mm wide, but hedgehogs often walk only on the toes of the hindfoot. The forefeet are wider rather than long; 30mm long and 35mm wide. The toes are slightly turned out from the mid-line. The toe pads are large relative to the footpad and closer to the central pad compared to rat or ferret prints. The claws are long and sharp and can show in prints. Sometimes the footprints will overlap.

When running the gait (distance between feet) is about 100mm and the body is held off the ground. When feeding or exploring the body is held lower and some of the spines may drag on the ground. Hedgehogs are also excellent swimmers and climbers.

Can be confused with:
Large rat and ferret prints. A hedgehog will have two different types of prints; hindfeet and forefeet. Rat prints have rather similar hind and forefeet but only four toes. Ferrets also only have four toes and fur can show in the prints, whereas hedgehogs have ‘bare’ feet. Hedgehog toe pads are proportionally larger and closer to the central cushion pad compared to rat or ferret prints. Hedgehog forefeet prints are rounder looking than rat or ferret prints.

Dens and nests

Hedgehogs’ dens are used for three purposes; as daytime retreats during the active season; breeding nests for females and young; and for hibernating during winter. They build nests on dry well drained sites where they can build an oval chamber in loose soils or leaf-matter. Nests are often found against a supporting structure such as fallen logs, against buildings or beneath a large shrub. Hedgehogs will usually have several day-time nests, and these are sometimes utilised by other hedgehogs when not occupied.

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Vegetation Damage

Hedgehog understorey damage.
Hedgehog leaf damage.
Hedgehog damage to fruit and flowers.

Understorey (less than 3m)

Analysis of hedgehog stomach contents in New Zealand often found some vegetation, especially mosses, grass and clover leaves, dead podocarp leaves, occasional seeds (mainly grass seed), and berry seeds.

Plant leaves

Fruits and Flowers

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Kill Sign

Hedgehog eating a frog.
Hedgehog kill - examples needed of other vertebrates preyed on.
Hedgehog invertebrate kill sign.
Hedgehog egg predation.

Fur, feathers or scales (vertebrate)

Birds

Hedgehogs are known to eat chicks of ground nesting birds, and are known to be significant predators of the eggs and nests of ground nesting birds inhabiting braided rivers in the South Island. They will also attack birds brooding on nest on the ground. Feathers have been found in hedgehog stomachs and dropping .

Mammals

Hedgehogs are known to eat mice. Mouse fur has been found in hedgehog stomachs and droppings . They can also scavenge carcasses such as rabbit and sheep.

Lizards and frogs

Lizard and frog parts have been found in hedgehog droppings and intestines. One study found that more than 20% of hedgehogs had skink remains in their stomach, and this included at least 43 individual skinks . While native lizards appear to be of lesser importance as food than invertebrates, small, localised populations of lizards may still be threatened by hedgehog predation, and large numbers of hedgehogs can have a high impact on native reptile populations .

Can be confused with:
Other predators such as stoats, weasels, cats and rats. Remember, too, that animal remains might have been scavenged.

Insects or snails (invertebrate)

Hedgehogs eat a wide variety of seasonally available invertebrates, especially larger species such as field crickets, weta, moth larvae, black beetles, green chafer beetle, earthworks, slugs and snails. It is estimated that hedgehogs may eat 40% of grass grubs during the flight season. Earthworms are commonly eaten in pasture areas.

Eggs

Eggshell fragments have been found in hedgehog droppings and video footage has shown them taking eggs from ground nesting birds in the MacKenzie Basin. This footage also showed that hedgehogs may have a greater impact on eggs than previously thought, because they often break the egg and carefully lick up all the contents without ingesting eggshell fragments .

Can be confused with:
Other predators such as stoats, ferrets, weasels, possums, cats and rats. Remember, too, that egg remains might have been scavenged.

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Other Clues

Hedgehog bite marks on each side of a chewcard.
Hedgehog bite marks on a chewcard.
Hedgehog remains, showing some of the sharp pointy teeth.
Hedgehog distribution in New Zealand.

Bite marks

Hedgehogs are carnivores and insectivores, with a long snout and numerous (36) small teeth: twenty on the upper jaw and 16 on the lower jaw. They have 10 incisors, 4 canines, 10 premolars and 12 molars.

On the upper jaw, two of canines are prominent and on the lower jaw two blunt incisors are prominent. Consequently, bite marks on each side of a chewcard will differ, with crush marks from the blunt incisors on one side and small marks from the sharp canine teeth on the other.

For further guidance, including illustrated examples, see the Manaaki Whenua – Landcare Research chewcard interpretation guide and other more technical identification guides.

Distribution

Hedgehogs occur on the three main islands (North Island, South Island and Stewart Island) and some offshore islands. They are abundant through the lowland and coastal districts, less numerous in hills, and scare in mountainous areas, although their presence in these areas may be increasing. They tend to be scarce or absent from areas that receive more than 250 frosty days per year and areas that receive more than 2500 mm of rain per year.

Smell

Hedgehogs do not have scent glands like ferrets, and generally produce very little odour, but they do have a characteristic smell. Younger hedgehogs and pregnant/nursing females also tend to have much stronger scented urine and droppings.

Sound

A very noisy animal and movement through leaf litter and snuffling can often be heard before the animal is sighted.

Can be confused with:
Kiwi can be similarly noisy in understorey, including snuffling noises at times.

Body covering

Each spine is a single modified hair about 20-25 mm long. The spines are creamy white, darkening to grey-brown at the base, with a broad dark bank just below the sharp point. The belly fur is coarse grey to pale brown hair with various patterns and mottles.

Can be confused with:
Nothing else like it in New Zealand.

Eye shine

Red eyes low to the ground

Can be confused with:
Possum on the ground

Other

Hedgehogs are the most commonly found road-kill species in New Zealand. Corpses on the road in your area indicate, of course, that there are hedgehogs present.

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MORE ABOUT HEDGEHOGS

Origin

Hedgehogs were introduced to New Zealand from Britain to remind the settles of their homeland and to help control garden slugs, snails and insects. The first pair landed in Canterbury in 1870. Before the impacts of hedgehogs on our native species were widely known, it was common to feed milk or cat food to hedgehogs in urban gardens.

Description

An unmistakable small mammal, grey-brown in colour with its back and sides entirely covered with spines.

Size and weight

They are 150-270mm in overall body length and reach a maximum of around 700 g in New Zealand (they can be heavier in colder countries in Europe). Their weight can drop dramatically during winter hibernation. There is no obvious difference in size or weight between sexes, although males tend to be slightly larger than females

Behaviour

Normally solitary, though mothers may be seen with well developed young. They are nocturnal, with most activity occurring in two distinct periods; in the two to three hours after sunset; and again between 8 and 9 hours after sunset. They can sometimes be seen at dawn and dusk. If seen out during the day then they are either looking for water during periods of drought, blinded by a parasite, or too sick or undernourished to hibernate. They roll in to a tight ball when threatened and this causes the spines (really modified hairs) to stand up.

A hedgehog hibernates in winter, when mean soil temperatures fall to10-11°Celsius. Length of hibernation varies widely according to climate – in a few coastal and northern areas very few hedgehogs hibernate, while in colder regions nearly all do so for prolonged periods. Males usually emerge from hibernation about a month before the females do. Winter dens tend to be under tree roots or deep dry litter, in rabbit burrows or other dry refuges.

The breeding season is prolonged, and seemingly more so in northern areas of New Zealand; beginning as early as September and young may be born as late as May. In the United Kingdom two litters can be produced per year of 4-7 young. In New Zealand, juvenile mortality is high and nests found average only 2.7 young. Young are independent after about seven weeks. Studies in New Zealand estimate that the average lifespan ranges from 1.97 to 2.67 years, but some hedgehogs can live up to four years in the wild.

Older animals can be determined by pale noses, spines and footpads – on young animals these are usually much darker. Teeth-wear also gives an impression of age, though both the above can be inaccurate. Accurate ageing can only be determined by examining a cross section of the lower jaw bone under a microscope – annual ‘growth-rings’ are often detectable.

Diet

Mainly insectivorous, with key prey items being larger insects such as beetles and weta and slugs, snails a, but they will eat almost any animal substance and some plant material. They are known to eat mice, lizards, frogs, and eggs and chicks of ground nesting birds. They find much of their prey by smell. It is estimated that hedgehogs can eat 160g of invertebrates per day.

Habitat

Preferred habitat is coastal and lowland pastoral areas, and they become rarer with increasing altitude. Although previously thought not to occur in any abundance within extensive native forest, recent studies show they are regularly trapped within large forest tracts such as Trounson and Rotoiti, and are found above the bush line in extensive forest areas such as the Kawekas. The density of hedgehogs is variable depending on terrain, habitat, and food availability; estimates range from 0.88 hedgehogs per hectare (mixed pasture and native forest) to 5.5 per hectare in native forest at Boundary Stream.

Home ranges vary considerably, both seasonally and between sexes. On farmland in the Manawatu home ranges averaged 2.5ha for males and 3.6ha for females. In the MacKenzie Basin home ranges had core areas of 8 ha but some animals wandered over areas of 100ha. A Lower Hutt study showed 95% of all animals stayed within an 800m radius (200ha area) of the initial capture site. Home ranges are not defended and can overlap with many other hedgehogs.

Hedgehogs will usually have several day-time nests, and these are sometimes used by other hedgehogs when not occupied. Population densities in known studies are from 1.1–2.5/ha. Hedgehogs can travel up to 3 km in one night. Hedgehogs are also excellent swimmers and climbers.

Distribution

See distribution clue.

How to get rid of hedgehogs

Contact the local DOC or Regional Council office for advice (see Next Steps). Hedgehogs are usually trapped. They have a very high tolerance for brodifacoum poison, and many other naturally occurring poisons.

FIND MORE INFORMATION IN:

Dowding, J.E. (1997). Protecting New Zealand dotterels from predators. In Sim, J.; Saunders, A. (Eds), National Predator Management Workshop. Wellington, New Zealand: Department of Conservation.

Hendra, R. (1999). Seasonal abundance patterns and dietary preferences of hedgehogs at Trounson Kauri Park. Conservation Advisory Science Notes No. 267. Wellington, New Zealand: Department of Conservation.

Jones, C., & Sanders, M.D. (2005). European hedgehog. InKing, C.M., (Ed.), The handbook of New Zealand mammals (pp. 81-94). Auckland, New Zealand: Oxford University Press.

Moss, K.A. (1999). Diet, nesting behaviour and home range size of the European hedgehog (Erinaceus europaeus) in the braided rivers of the Mackenzie Basin, New Zealand. MSc Thesis, University of Canterbury, Christchurch, New Zealand.

Reardon, J.T., Whitmore, N., Holmes, K.M., Judd, L.M., Hutcheon, A.D., Norbury, G., & Mackenzie, D.I. (2012). Predator control allows critically endangered lizards to recover on mainland New Zealand. New Zealand Journal of Ecology 36(2).