Eli5 : why are bigger birds generally faster than smaller birds?

Question

The way I think about it, smaller birds have less weight and less wind resistance. Shouldn’t that mean they would be faster?

In: 7

Answer 1

In straight line flight, smaller birds tend to win the race(a peregrine falcon will lose a race with a common pigeon in straight line flight). Larger birds, specifically raptors, tend to use gravity to gain momentum and can thusly outpace smaller birds.