Rufous hummingbirds (Selasphorus rufus) have been called the most important hummingbird pollinator in western North America. This is because rufous hummingbirds migrate from Alaska to Mexico, pollinating plants the entire journey. As the birds stop along nectar corridors to eat they inadvertently collect pollen and transfer it to another plant, often times moving genetic material great distances. In the 1960s these birds were seen pollinating the giant trumpets (Macromeria viridiflora) plant in Arizona, the first documented case of a hummingbird pollinating a member of the Boraginaceae family in western North America. M. viridiflora is a tall perennial herb with yellow tubular flowers. The hummingbird probes the floral tubes by fitting its bill into the upper part of the floral tube and extending its tongue to reach the nectar in the narrow, lower part of the tube. Pollen then becomes dusted on the hummingbird's bill and is inadvertently transferred when the bird moves from plant to plant eating nectar. The hummingbird's role as a pollinator during migration is believed to have influenced the speciation of California flowers. This species of hummingbird is declining throughout its range, and the loss of nectar corridors across its migration route may continue to threaten this bird.