Migration Info This unassuming flycatcher slips into the United States in late spring and passes back into Mexico well before winter, after a short (70- to 90-day) breeding season. The bulk of the western population moves north along the Pacific coast of Mexico, then fans out across the western United States. Eastern populations move north and east after crossing western Texas. Although this bird spends most of its life in migration or on its wintering grounds in South America, the major threat to this species is loss of breeding habitat in the United States. The Southwestern subspecies (now on the U.S. Endangered Species List) is threatened by loss of habitat due to water diversion practices, livestock overgrazing, and non-native plants that degrade critical breeding habitat.