Bird migration 101
Each spring and fall, many North American birds move between breeding and nonbreeding ranges. Much songbird migration happens at night, while other groups move by day.
Scope: North American bird migration; BirdCast county estimates cover the contiguous United States · Last updated
The four flyways
Atlantic, Mississippi, Central, and Pacific flyways are broad North American management units, especially useful for waterfowl and shorebirds. They are regional shorthand, not fixed aerial highways. Many songbirds migrate on broad fronts and are not confined to one flyway, so use species-specific range and timing data alongside the map. [1][4]
When it happens
BirdCast's live dashboard runs March 1–June 15 and August 1–November 15. Those dates describe the dashboard data feed, not biological start and end dates; migration timing varies by species, latitude, and year. [3]
- Spring: roughly March 1 – June 15
- Fall: roughly August 1 – November 15
- Peaks within those windows vary by latitude and species
Most of it is at night
Many songbirds migrate after dark; raptors, swallows, and some waterfowl also migrate by day. BirdCast estimates nocturnal movement from weather radar for the contiguous United States, so its county totals do not describe every migrant or all of North America. [2][3]
What it asks of you
Artificial light can attract and disorient nocturnal migrants, and glass collisions are a major hazard. On migration nights, switch off nonessential outdoor and upper-story lights, close blinds, and use bird-safe treatments that make glass visible. [5][6]
Identify it and save the field note.
Where this guide comes from
Source-checked editorial guide. Last updated . This guide teaches identification and field skills; it is not a substitute for expert verification when it matters.
- U.S. Fish & Wildlife Service — Migratory Bird Program Administrative Flyways ↗
- Cornell Lab of Ornithology (All About Birds) — The Basics of Bird Migration ↗
- BirdCast — Local Migration Dashboard ↗
- Cornell Lab of Ornithology — The flyways birds use ↗
- BirdCast — Lights Out ↗
- U.S. Fish & Wildlife Service — Bird collisions with building glass ↗
