Many small passerines (perching birds) that breed in North America migrate to the Neotropics for the winter. While most eastern breeders molt (replace their worn feathers with new ones) before heading south, many western birds do not. Presumably because western habitats tend to become so hot, dry, and inhospitable during the late summer, these birds head to areas where food is more abundant before growing their metabolically expensive new feathers. Burke researchers have found that Arizona, New Mexico, and northern Mexico—areas inundated by the Mexican Monsoon in late summer—provide an important place for certain bird species to stop and molt before proceeding to their wintering areas further south. Burke Ornithology staff and students are conducting a series of late-summer expeditions to assess which bird species are taking advantage of these wetter, food-rich areas, and whether any of the habitats they use while molting are sufficiently degraded by recent human activity to raise conservation concerns.
Read more about 'Molt and the Mexican Monsoon'.