Willow Ptarmigans molt their mottled brown summer plumage for snow-white feathers that provide camouflage when winter snows arrive.
(Willow Ptarmigans; molt; their mottled brown summer plumage for snow-white feathers) (snow-white feathers; provide; camouflage; T:when winter snows arrive) (winter snows; arrive; )
Willow Ptarmigans snow-white feathers winter snows
molt provide arrive
their mottled brown summer plumage for snow-white feathers
camouflage T:when winter snows arrive