Barn Swallows are annual in summer and early fall on the Pribilof Islands. Two or three subspecies of Barn Swallow are possible on Saint Paul. Two of these, Hirundo rustica rustica and H. rustica gutturalisare old-world in distribution and are white bellied. Separating these two forms is difficult and centers mainly upon whether the blue breast collar is complete (rustica) or incomplete (gutturalis). The third subspecies is the North American form, H. rustica erythrogaster, which generally shows rusty underparts. On a typical year, one to four Barn Swallows will be detected between early June and early August. Roughly half of the sightings are of old-world birds. Barn Swallows can be found around any of the island’s marshy areas and also (for some unknown reason) around the airport buildings.