From the beginning in New Zealand there were no small ground mammals – islands were separated from the common body of southern supercontinent Gondwana too early. Therefore in absence of competition one local New Zealand bat, Mystacina tuberculata, which had adapted to partly terrestrial habit of life, replaced them. Introducing of mammals by people had radically changed the situation and had changed the direction of evolution of local species of animals. Among the introduced species of mammals there were hoofed mammals, predators and marsupials. From the group of insectivorous mammals the European hedgehog had got to islands. It had easily accustomed in new place of inhabiting, and its descendants had equally easily outlived humans. The Neocenic descendant of hedgehog, tiny shrew-like hedgehog has occupied the ecological niche of small insectivorous animals, finally having superseded bats from it. This creature is the tiny mammal similar to shrew in size and habits. At it needles characteristic for hedgehogs are reduced and have remained only on head, and grow as the longitudinal strip on back. It is connected to change of way of life: the former sluggish creature has turned in fast small mammal scurrying among bushes and grasses; speed has replaced to it passive protection with the help of needles. But in behaviour of shrew-like hedgehog nevertheless there are the features inherited from an ancestor and connected with ability to be self-protected by means of needles. Tiny shrew-like hedgehog is rather aggressive, despite of small size. At the attack of predator even if it is much larger than this mammal, shrew-like hedgehog is protected actively. It bites the enemy by peaked needle-like teeth, runs into it and tries to strike bristling needles growing on head. Shrew-like hedgehog is colored very contrastly. Its needles are colored white, and wool on body is black – it is warning colouring which is perceived even by animals lack of color sight. Being protected from the enemy, the animal utters shrill peep (almost ultrasound) which is not loved by many animals with keen hearing. Therefore birds and mammals usually avoid to attack tiny shrew-like hedgehog, and kill it casually in small amount. One of main enemies of this animal is large New Zealand mouse-eating gekko, the large lizard living in wood litter and hunting from ambush. Tiny shrew-like hedgehog is solitary territorial species. The individual site is carefully marked by musk substance which is secreting from glands located near the anal aperture. This animal is active in twilight and at night though separate animals hunt in the afternoon, especially in shady cool woods. Males and not sexual matured females do not arrange constant shelters and spend day in temporary refuges. Only the pregnant female arranges a constant nest in bush: she digs out a hole up to half meter deep, or occupies another's one. The entrance in hole is disguised and protected by branches. Occasionally shrew-like hedgehogs get in holes of – herbivorous animals, settling in big colonies. In holes these small mammals eat various insects, and sometimes attack newborn rabbit cubs. But such cases are casual, and take place only in weak colonies, where there are few adult animals. This animal is carnivorous, and also eats only insects and other small invertebrates. Shrew-like hedgehog has inherited from ancestor exclusive resistance to poisons; therefore it frequently attacks even on poisonous centipeds and eats them without harm for itself. It bites such dangerous animals in head to kill on the spot. Frequently shrew-like hedgehog attacks lizards twice heavier, rather than itself. In this case it carries off catch in bushes (despite of small size, it is very strong) and stays near the catch, yet will to have eaten it completely. Rate of metabolism at tiny warm-blooded animal is very high; therefore shrew-like hedgehog is compelled to eat almost constantly, with small breaks on. For day it eats the amount of food one and half times more, than it weighs. This animal lives a little and very quickly. The female matures at the age of about two months. After pregnancy, which lasts about 12 days, she gives rise to 5 – 8 tiny, blind, helpless cubs. They completely develop at fortnight age, and three-week old mammals already lead independent life. Bringing up posterity, the female is strongly exhausted. In one month after the posterity has abandoned the female, she restores the physical condition and is ready to pairing again. The close species, mountain shrew-like hedgehog (Microerinaceus montanophilus), lives in mountains of New Zealand. It is larger (rat-sized) and more aggressive species of mammals. Needles on its head are reduced, but on back there is a crest of firm cross-striped needles. At danger it rears needles and stirs them up, turning to the opponent sideways. This species also leads solitary way of life and is a predator. It frequently attacks lizards and small mammals.