Excluding bacteria and viruses but including marine organisms, the total number of animal and plant species in Norway is estimated at 60,000. This includes 16,000 species of insects (probably 4,000 more species yet to be described), 450 species of birds (250 species nesting in Norway), 90 species of mammals, 45 fresh-water species of fish, 150 marine species of fish, 1,000 species of fresh-water invertebrates, and 3,500 species of marine invertebrates.
Terrestrial mammals on mainland Norway include the European hedgehog, six species of shrews and ten of bats. The European rabbit, the European hare and the mountain hare all live here as do the Eurasian beaver, the red squirrel and the brown rat as well as about fifteen species of smaller rodent. Of the ungulates, the wild boar, the muskox, the fallow deer, the red deer, the elk (N. American usage: ‘moose’), the roe deer and the reindeer are found in the country.
Terrestrial carnivores include the brown bear, the Eurasian wolf, the red fox and the Arctic fox, as well as the Eurasian lynx, the European badger, the Eurasian otter, the stoat, the least weasel, the European polecat, the European pine marten and the wolverine. The coast is visited by the walrus and six species of seal, and around thirty species of whale, dolphin and porpoise are found in Norwegian waters.
Norway has a great variety of bird species utilising its many habitats, cliffs, wetlands, forests and tundra. In the summer, insects and other food sources are plentiful and the days are long, giving plenty of time for birds to forage and feed their young. This is not the case in winter when the ground is covered in snow, the wetlands in ice and the days are short, so many of the birds are migratory, usually breeding in Norway and overwintering in southern Europe or Africa.