The most common breeding passerine in the Pribilofs, this species is abundant during much of the spring, summer, and fall, though it is absent during the winter. The males arrive first in the spring, typically during the last few days of April or first week of May, with the females often a week or so behind. This species is common by mid-May and in full nesting numbers by the end of the month. The breeding season spans June and much of July, with fledglings typically seen first during the final 10 days of July and rapidly increasing numbers (both non-breeding adults and young birds) noted by the beginning of August. Peak congregations of this species are typically noted from mid-August to mid-September, when large numbers gather prior to their fall migration from the islands. Numbers continuously decline through the end of September and first part of October with only small numbers remaining by mid-month. Those individuals typically leave soon after and there are no known November records.
