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  Hedgehog  (Erinaceus europaeus)    
  Description | Behaviour and Life-cycle | Ecological Impacts| Field Sign    
       
 
Description


An unmistakable small 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.



   
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Behaviour and Life-cycle


Strongly nocturnal, with most activity occuring in two distinct periods, in the two to three hours after sunset, and again between 8 and 9 hours after sunset.

Rolls into a tight ball when threatened.

Hibernates in winter, when mean soil temperatures fall to 10-11o 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. Winter dens are 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, beginning as early as September and young may be born as late as May. Two litters can be produced per year, of 4-7 young. Juvenile mortality is high and nests found average only 2.7 young. Young are independent after about seven weeks.

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 jawbone under a microscope – annual ‘growth rings’ are often detectable.

Average lifespan appears to be in the vicinity of 2-3 years and the oldest may live to 7-10 years.

Preferred habitat is lowland pastoral areas, and they become rarer with 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 eg Trounson, Rotoiti, and are found above the bushline in extensive forest areas such as the Kawekas.

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 8ha but some animals wandered over areas of 100ha. A Lower Hutt study showed 95% of all animals stayed within an 800m radius (256ha area) of their initial capture site.

Home ranges are not defended and can overlap with many others.

Hedgehogs will usually have several daytime nests, and these are sometimes utilised by other hedgehogs when not occupied.

Population densites are from 1.1 – 2.5 hedgehogs per ha.

Hedgehogs can travel up to 3 km in one night.

Normally solitary, though mothers may be seen with well developed young.

Mainly insectivorous, with key prey items being slugs, snails and larger insects, but they will eat almost any animal substance and some plant material. Finds much prey by smell.


   
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Ecological Impacts


The main negative ecological impact of hedgehogs in New Zealand is probably predation on the eggs and chicks of ground dwelling birds. They are proven predators on 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, to the size of young turkey poults. Small ground nesting species such as pipit would be particularly vulnerable. Hedgehogs have been shown to be serious predators of colonial nesting seabirds in Britain.

Hedgehogs are a major predator of northern populations of New Zealand dotterel.

May have significant impact on native slug and snail and terrestrail insect populations. They have a voracious appetite for invertebrates and take many local endemic species.
They are known to eat the rare giant native centipedes, and rare insects in the MacKenzie Basin.

They have been known to eat the native snail Wainuia urnula. 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 populaton recovery.

Likely to prey upon 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.


   
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Field Sign


Prints are five-toed, resembling a large rat print. Forefeet are much broader and shorter in length than the hind feet, meaning there are two distinctly different prints left by the one animal.

Droppings are black (with a dark greenish colour to fresh droppings), 20-50mm long and 7-10mm wide. They are usually dryish, and usually contain tightly packed recognisable fragments of invertebrate exoskeletons eg. beetle carapaces, head or body segments.

Movement and snuffling can often be heard before the animal is sighted.

 

 

   
       
  Description | Behaviour and Life-cycle | Ecological Impacts| Field Sign    
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