OUTSTANDING MIGRATION AND NESTING RECORDS OF SWAINSON’S HAWKS IN SOUTHERN SONORA, MEXICO

Abstract

We report multiple sightings of Swainson’s Hawks (Buteo swainsoni) migrating through the Yaqui Valley of Sonora, Mexico, in fall from 2021 to 2023. The hawks occurred in flocks of up to 800, associating with Turkey Vultures (Cathartes aura), Crested Caracaras (Caracara cheriway), and other birds foraging in farmland being plowed and tilled before the sowing of wheat for the fall–winter cropping season. On the basis of seven nests from 2023 to 2025, we also report the first evidence of Swainson’s Hawk nesting in the region, representing a southward expansion of the known breeding range by >250 km into the coastal plain of northwestern Mexico.