Even with the compensation of larger wings per unit body mass, larger birds also have a slower wing beat frequency, which allows larger birds to fly at higher altitudes, longer distances, and faster absolute speeds than smaller birds.
Larger birds also have a slower wing beat frequency. This is even with the compensation of larger wings per unit body mass. Frequency allows larger birds to fly at higher altitudes than smaller birds. Frequency allows larger birds to fly at longer distances than smaller birds. Frequency allows larger birds to fly at faster absolute speeds than smaller birds.