Birds Ascending the Heights

Because of reports of planes colliding with birds at very high altitudes and the stories about the Bar-headed Geese that migrate over the Himalayas, cresting above Mount Everest, one could get the impression that bird migration normally occurs at immense heights. With the help of radar, however, we know which altitudes are common and which are unusual.

Birds behave somewhat differently from one species to the next, but songbirds fly at altitudes of less than 5,000 feet, and the majority travel no higher than 2,500 feet. Waterfowl and shore birds tend to fly higher; it is not unusual to detect them above 10,000 feet or even as high as 20,000 feet, especially when they are making long, over-water flights.

Moody spring and fall skies often mean low cloud ceilings that force migrating birds to fly lower than usual. High-flying birds, such as Geese, sometimes ascend through the cloud cover to migrate in the clear skies above.