On a day-to-day basis, most birds usually fly below 500 feet. Have you ever been in a tall skyscraper? Five hundred feet is about the height of the average 50-story building.
During migration, however, many birds choose to fly much higher than on a normal day, at anywhere between 5,000 and 30,000 feet. Most passenger airplanes fly at about 30,000 feet, so a migrating bird could be all the way as high up as that!
If you were a bird, what do you think would be some advantages of flying up higher versus flying down lower? Do you think it would be helpful to be higher up from trees and buildings? Or would it be better to avoid going really high up unless you needed to, in order to help save your energy??
Sources & links
“How high can a (commercial or military) jet aircraft go?” Ask Experts. PhysLink.com. 24 Jul. 2011 “How Fast and High Do Birds Fly?” Stanford Birds. Stanford University. 24 Jul. 2011 “Fact Sheet: Neotropical Migratory Bird Basics.” Migratory Bird Center. Smithsonian National Zoological Park. 24 Jul. 2011 Unit Converter: Concert Foot to Story. ConvertUnits.com. 24 Jul. 2011