Willow ptarmigans (Lagopus lagopus) in the Arctic change colour throughout the year, from completely brown in mid-summer to completely white in mid-winter. The transition (which starts from the head and moves down) is triggered by changing day length, not by temperature.
With a warming Arctic, we are now seeing snow-white birds in a snow-less landscape. Where once they were perfectly camouflaged as the seasons changed, now they are sitting ‘ducks’ for predators. The climate change is happening too quickly for them to evolve to meet the new conditions.
The willow ptarmigan’s scientific name, Lagopus lagopus is derived from Ancient Greek lagos (λαγως) ‘hare’ + pous (πους) ‘foot’, in reference to the bird’s feathered feet which allow it to negotiate frozen ground.
Thanks, Max Romey, for introducing me to this bird and its story.