Remarkably hardy n. bird. Occurs to s. less than very similar CORE (1:80 in USA). Almost always found in CORE flocks. Id with care! Usually picked out by paler gray upperparts. Look for fewer, better defined streaks on underparts, less contrasting and paler face, few or no streaks on undertail coverts, and all- or mostly white rump. Sometimes has shorter ‘nipped in’ bill, more feathering around leg. Age and sexing as CORE. ♂: only lightly pink-breasted and more lightly streaked. exilipes widespread. Scarcer hornemanni, from Baffin Is and Greenland, is noticeably larger and bigger-headed, also averages paler.