Birds of prey migration begins in the northern hemisphere when days grow short and the weather grows colder. Food becomes less abundant. They usual food sources migrate (songbirds) , burrow underground or hibernate (small rodents). Raptors leaves for places where small birds, reptiles and small mammals are active and easily found.
Raptors will migrate a few hundred miles or several thousand each way to better food sources. Some raptors travel to different parts of North America and others to Central and South America.
They travel along using the same flyways and navigation methods as other birds. Hawk migration routes often follow isthmuses, peninsulas and mountain ridges.
Raptors are birds that soar. That is one of the most noticeable things about them. It is that effortless soaring that mesmerize us as we gaze at them in the sky. Raptors soar by “catching thermals”, like surfers catch a wave. Thermals are columns of warm air that rise over sun-heated surfaces such as parking lots, agricultural fields, and rocky areas that reflect heat. The birds float on the rising columns of heat. When one thermal dissipates, the bird glides to another and continue on over long distances.
Raptors are unable to fly over water for long-distances. Because water doesn’t conduct heat into thermals like land forms do.
By soaring and gliding, raptors expend little energy.
There are many places in North America to see hawk migration. The Hawk Watch Site Selection for North America has a click a map to find a spot. They return north in the spring. When northern food sources are awake and running or flying around. then there is more food to feed hungry nestlings.
Places to watch raptor migration in the Philadelphia area