Willow ptarmigan a range of lower plant species. It is also believed that the greening of parts of the Arctic is affecting Willow Ptarmigan populations by altering the shape and size of the shrubs they are able to feed on. Male willow ptarmigans are territorial birds. Males arrive in the breeding areas and set up territories in April and May, aggressively defending them against male interlopers. When the females arrive a few weeks later, the male performs courtship displays such as aerial manoeuvres, strutting and tail-fanning. When she has chosen a mate and a nesting site, the female lays a clutch of
Arctic fox regulation. Also, the Arctic fox has a beneficial mechanism in their nose for evaporative cooling like dogs, which keeps the brain cool during the summer and exercise. The thermal conductivity of Arctic fox fur in the summer and winter is the same; however, the thermal conductance of the Arctic fox in the winter is lower than the summer since fur thickness increases by 140%. In the summer, the thermal conductance of the Arctic foxes body is 114% higher than the winter, but their body core temperature is constant year-round. One way that Arctic foxes regulate their body temperature is by