Cute images Øivind.
They are known as stoats in New Zealand, where they were introduced to help control the plaques of rabbits resulting from the introduction of that species.
Stoats have caused untold havoc in respect of the native bird populations (along with the weasels, ferrets, hedgehogs etc etc). Fortunately the British stopped short of introducing foxes like they did in Australia. Then there is the havoc caused by the plant species that were introduced such as broom, gorse, lupins, nightshade, hemlock etc etc ....