- Migrants return to their breeding grounds when weather and food permit, usually January–March.
- During spring, adult eagles move north rather rapidly, despite not-yet-ready conditions at their breeding grounds because their internal biological clocks are telling them breeding time is near. The hormonal drive to initiate nest building and courtship overwhelm the difficulties in finding food during this period.
- Some bald eagles that reside in the southern United States migrate slightly north during hot summer months.
- Some biologists describe bald eagle migration as seasonal movements, rather than a true migration. This is because almost all bald eagles only move away from their nesting areas as far as they need to in order to find the food they need to survive.
- An eagle can circle in a strong thermal to a high altitude, then glide long distances in the direction of its migration until it finds the next column of rising air.
- Migrating birds get directional information from landscape features and wind direction which can be influenced by major land forms, scents, the stars and sun, as well as Earth's magnetic field (increasing evidence indicates that birds collect magnetic field information through specialized eye receptors).
- Migrating eagles fly during the day at speeds averaging 30 miles per hour. To help them soar, eagles use thermals, which are rising currents of warm air and up-drafts generated by terrain, such as valley edges or mountain slopes. Soaring is accomplished with very little wing-flapping, enabling them to conserve energy.
- Long-distance migration flights are accomplished by climbing high in a thermal, then gliding downward to catch the next thermal, where the process is repeated.
- Bald eagles tend to migrate in groups. A stream of migrating bald eagles can be twenty to thirty miles long, with birds spread out about a half mile apart.
- A majority of bald eagles nest in Alaska and remote areas of Canada. A small number nest in the United States in areas where isolation can still be maintained. Major nesting areas are concentrated in: the Far West, (Alaska, the San Juan Islands off the coast of Washington, as well as Washington, Oregon, and northern California); the Upper Midwest (central and northern Minnesota, northern Wisconsin and upper Michigan); and the East Coast (Maine, the Chesapeake Bay area, and Florida).
- Northern birds return to breeding grounds as soon as weather and food availability permit, generally January to March.
- Bald eagles’ breeding range spans the continent from Alaska to Newfoundland, and south to Baja California and Florida. In spring, eagles migrate in two stages: adults first, then immatures. They fly during daylight and often over ranges of hills and other areas of high relief where thermal updrafts facilitate their flight.
- Eagles in spring won't move much on overcast days. Rain or snow or low clouds can cause eagles to stop moving until conditions clear.
- According to telemetry studies, migrating eagles can fly as many as 225 miles in a day. The average distance per day of one of our eagles was 98 miles.
- Eagles are thought to migrate during the day, primarily between 8 am and 6 pm, with most not starting until mid-morning or later, perhaps giving the sun a chance to create more suitable thermals.
- Generally, eagles are nowhere near as weather dependent for movement as songbirds are. Songbirds (and most other birds) migrate differently than eagles and other raptors. Raptors migrate by soaring-gliding flight rather than by flapping-flying flight as in other birds. This obviously conserves tremendous amounts of energy, but also indicates that ideal weather conditions for migrating are different for the two groups. Many other species of birds also migrate at night, while bald eagles move strictly during the daylight hours.
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