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Facts about hedgehogs

Hedgehog. Photo: Don Merton.
Hedgehog

Hedgehogs were first brought to New Zealand by acclimatisation societies to remind settlers of their homeland, but were later introduced in greater numbers to control garden pests such as slugs, snails and grass grubs.

Today, hedgehogs are abundant throughout New Zealand, and pose a significant threat to many of our native species.

In many areas of New Zealand, there are now estimated to be between two and four hedgehogs per hectare (and in some areas as many as eight!)

Description

The hedgehog is an unmistakable small nocturnal mammal, grey-brown in colour with its back and sides entirely covered with spines. They are 150-250mm in overall body length and reach a maximum of around 1kg, but their weight can drop dramatically during winter hibernation.

Though males tend to be slightly larger than females the difference in size and weight is not obvious.

Behaviour and life-cycle

Hedgehogs rely on their spines for protection and roll into a tight ball when threatened.

In winter, hedgehogs hibernate.  Winter dens are under tree roots or deep dry litter, in rabbit burrows or other dry refuges. Male hedgehogs begin hibernation much earlier than females.

Then in spring, as early as September, the long breeding season starts, yet young may be born as late as May. Two litters can be produced per year, each of 4-7 young; however juvenile mortality is high.  The young are independent after about seven weeks.

Hedgehogs’ preferred habitat is lowland pastoral areas, and they become less common with increasing altitude. Although previously thought to be mostly absent from extensive forest, recent studies show they are regularly trapped within large forest tracts (for example in Trounson and Rotoiti), and are found above the bush line in extensive forest areas such as the Kawekas.  Home ranges are not defended and can overlap with many others. Hedgehogs will usually have several daytime nests, which are sometimes used by other hedgehogs when not occupied.

Hedgehogs are mainly insectivorous, with key prey items being slugs, snails and larger insects, but will eat almost any animal substance and some plant material. They find much of their prey by smell.