It is easy to assess the speed of horses and people in races because there is a start and a finish line, but it is much harder to measure the speed of a bird in flight.

Many figures have been published about the speed in flight of various birds but most authorities doubt these statistics.

In general, the heavier the bird is, the faster it needs to fly in order to stay in the air. One expert believes that the fastest recorded flight for a bird was that of a homing pigeon going at 94.2 miles per hour.

Here are the estimated speeds that some birds fly at:

The peregrine falcon can fly at about 65 to 75 miles per hour, the next fastest are ducks and geese who can go at about 65 to 70 miles per hour.

The European swift, golden plover and dove can reach 60 to 65 miles per hour, while hummingbirds reach speeds of 55 to 60 miles an hour. Starlings fly at about 45 to 50 miles and swallows usually at about 25 miles per hour.