White wagtail
Motacilla alba 
Identification Tips:
-  Slender bill
-  Black cap, nape, throat and upper breast
-  White forehead and side of face
-  Black eyeline
-  Gray back
-  White patch in wing
-  White underparts
-  Black tail with white outer tail feathers
-  Dark legs
-  Female has pale throat
-  Juveniles have duller, browner plumage
-  Breeds in Alaska
Similar species:                        
Black-backed Wagtail is similar to White Wagtail.  Male has black, not
gray, back and more white in wings.  Females and juveniles very similar.