ult s ▁have ▁white ▁under parts , ▁though ▁the ▁rest ▁of ▁the ▁pl um age ▁goes ▁through ▁a ▁complex ▁m oul ting ▁process . ▁The ▁male ▁has ▁a ▁long ▁pointed ▁tail ▁( ▁long ) ▁and ▁a ▁dark ▁grey ▁bill ▁crossed ▁by ▁a ▁p ink ▁band . ▁In ▁winter , ▁the ▁male ▁has ▁a ▁dark ▁che ek ▁patch ▁on ▁a ▁mainly ▁white ▁head ▁and ▁neck , ▁a ▁dark ▁breast ▁and ▁mostly ▁white ▁body . ▁In ▁summer , ▁the ▁male ▁is ▁dark ▁on ▁the ▁head , ▁neck ▁and ▁back ▁with ▁a ▁white ▁che ek ▁patch . ▁The ▁female ▁has ▁a ▁brown ▁back ▁and ▁a ▁relatively ▁short ▁pointed ▁tail . ▁In ▁winter , ▁the ▁female ' s ▁head ▁and ▁neck ▁are ▁white ▁with ▁a ▁dark ▁crown . ▁In ▁summer , ▁the ▁head ▁is ▁dark . ▁Ju ven iles ▁res emble ▁adult ▁females ▁in ▁aut umn ▁pl um age , ▁though ▁with ▁a ▁l ighter , ▁less ▁distinct ▁che ek ▁patch . ▁ ▁The ▁males ▁are ▁vocal ▁and ▁have ▁a ▁musical ▁y od elling ▁call ▁ow , ▁ow , ▁ow al - ow . ▁ ▁E col ogy ▁Their ▁bre eding ▁habitat ▁is ▁in ▁t und ra ▁po ols ▁and ▁mar sh es , ▁but ▁also ▁along ▁sea ▁coast s ▁and ▁in ▁large ▁mountain ▁la kes ▁in ▁the ▁North ▁Atlantic ▁region , ▁Al aska , ▁northern ▁Canada , ▁northern ▁Europe , ▁and ▁Russia . ▁The ▁nest ▁is ▁located ▁on ▁the ▁ground ▁near ▁water ; ▁it ▁is ▁built ▁using ▁veget ation ▁and ▁l ined ▁with ▁down . ▁They