The most common swallow species to occur in the Pribilofs, this species is regularly found in the spring from the final days of May through June 20th, with very few occurrences prior to May 28th and a peak of occurrence from June 5th-15th. Sightings decline after June 20th during the summer though it can still be found on occasion through early July, with only a few scattered records from the second half of July and the beginning of August. This species is not as common in fall as it is in spring with the first fall migrants appearing in the first days of August and a peak of occurrence from August 10th-20th; however, there are regular sightings through the end of the month. This species rarely occurs in September though it has been seen through the end of the month and into early October.
