Baby Hummingbirds In The Nest

Most hummingbirds of the U.S. and Canada migrate south in fall to spend winter in Mexico or Central America. A few southern South American species also move north to the tropics during the southern winter. A few species are year-round residents in the warmer coastal and southern desert regions of the USA. Among these are Anna's Hummingbird, a common resident from California inland to Arizona and north to the southwestern coastal and south-central interior of British Columbia, and Buff-bellied Hummingbird, an uncommon resident in subtropical woodlands of southern Texas.
Ruby-throated hummingbirds migrate from as far north as all regions of Ontario south to Central America and Mexico via direct crossings of the Gulf of Mexico or coastal Texas.
The Rufous hummingbird is one of several species that breed in temperate western North America and winter in increasing numbers in the warm subtropical southeastern United States, rather than in tropical Mexico. By migrating in Spring as far north as the Yukon or southern Alaska, the Rufous hummingbird nests farther north than any other hummingbird species and must tolerate occasional temperatures below freezing in its breeding territory. This cold hardiness enables it to survive temperatures below freezing, provided that adequate shelter and food are available.
The northward migration of Rufous hummingbirds occurs along the Pacific flyway and may be time-coordinated with flower and tree leaf emergence in Spring in early March, and also with availability of insects as food. Arrival at breeding grounds before nectar availability from mature flowers may jeopardize breeding opportunities, a factor of phenology possibly determining future migratory patterns linked to climate change.