Migratory Bird Activity

AIM ¶ 7-5-1 — Migratory Bird Activity

AIM 7-5-1 explains migratory bird strike risks, peak seasons, altitudes, hazardous species, and the four major U.S. flyways pilots should know.

In Plain English

Bird strikes are a real hazard, and the risk spikes during migration season — March–April and August–November. While over 90% of reported strikes happen at or below 3,000 feet AGL, strikes higher up are common during migration, and ducks and geese have been observed up to 7,000 feet AGL. Pilots are cautioned to minimize en route flying at lower altitudes during these months.

The species considered most hazardous — due to size, abundance, or flocking behavior — include:

Gulls
Waterfowl (ducks, geese)
Vultures
Hawks
Owls
Egrets
Blackbirds and starlings

The U.S. has four major migratory flyways:

Atlantic Flyway — parallels the Atlantic Coast
Mississippi Flyway — Canada through the Great Lakes, following the Mississippi River
Central Flyway — a broad band east of the Rockies, from Canada to Central America
Pacific Flyway — west coast, covering Washington, Oregon, and California

Numerous smaller flyways also cross these major routes. Knowing when and where birds migrate helps you plan safer altitudes and routes — this is recommended guidance, not a regulation.

AIM Source Text

FAA AIM ¶ 7-5-1

7-5-1. 7-5-1. Migratory Bird Activity Bird strike risk increases because of bird migration during the months of March through April, and August through November. The altitudes of migrating birds vary with winds aloft, weather fronts, terrain elevations, cloud conditions, and other environmental variables. While over 90 percent of the reported bird strikes occur at or below 3,000 feet AGL, strikes at higher altitudes are common during migration. Ducks and geese are frequently observed up to 7,000 feet AGL and pilots are cautioned to minimize en route flying at lower altitudes during migration. Considered the greatest potential hazard to aircraft because of their size, abundance, or habit of flying in dense flocks are gulls, waterfowl, vultures, hawks, owls, egrets, blackbirds, and starlings. Four major migratory flyways exist in the U.S. The Atlantic flyway parallels the Atlantic Coast. The Mississippi Flyway stretches from Canada through the Great Lakes and follows the Mississippi River. The Central Flyway represents a broad area east of the Rockies, stretching from Canada through Central America. The Pacific Flyway follows the west coast and overflies major parts of Washington, Oregon, and California. There are also numerous smaller flyways which cross these major north‐south migratory routes.

Oral Exam Questions a DPE Might Ask

Q1During what months is bird strike risk highest, and why?

Per AIM 7-5-1, bird strike risk increases during migration in **March through April** and **August through November**, when large numbers of migratory birds are in transit along major flyways.

Q2At what altitudes do most bird strikes occur, and how high have migrating birds been observed?

Per AIM 7-5-1, over **90% of reported bird strikes occur at or below 3,000 feet AGL**, but during migration strikes at higher altitudes are common — **ducks and geese are frequently observed up to 7,000 feet AGL**.

Q3Name the four major migratory flyways in the United States.

Per AIM 7-5-1, the four major flyways are the **Atlantic Flyway** (along the Atlantic Coast), the **Mississippi Flyway** (Canada through the Great Lakes following the Mississippi River), the **Central Flyway** (east of the Rockies from Canada to Central America), and the **Pacific Flyway** (west coast over Washington, Oregon, and California).

Related Paragraphs in AIM Chapter 7

¶ 7-5-2

Bird Strike Risk Reduction

¶ 7-5-3

Reporting Bird Strikes

¶ 7-5-4

Bird Strike Reporting

¶ 7-5-5

Wildlife Hazard Advisories

¶ 7-5-6

Flights Over National Parks

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