This common species is found at all seasons on the Pribilofs, though large seasonal changes do occur. The nesting habitat for this species in the Pribilofs is mostly located in the lava fields and rocky interior of the islands, away from the road systems on St. Paul and St. George Islands, with locally nesting individuals moving to these nesting grounds by late April and early May. As such, this species is present in the islands in large numbers but typically only seen in small numbers from May-July unless specific efforts are made to visit those areas. The first post-breeding gatherings are often noted during August or early September, with numbers of local and migrant individuals building through September and into October. Late fall movements are not well known though the majority leave the islands by mid-winter (December and January) with some (up to low hundreds) present through the winter. The first migrants likely begin to augment the wintering population in March or April.
