I heard it has a mean streak a mile wide!Actually I found a photo to the test mule.
http://mentalfloss.cachefly.net/wp-content/uploads/2007/11/00monty_python_rabbit.jpg
Which states "Although a definitive answer would of course require further measurements, published species-wide averages of wing length and body mass, initial Strouhal estimates based on those averages and cross-species comparisons, the Lund wind tunnel study of birds flying at a range of speeds, and revised Strouhal numbers based on that study all lead to the estimate that the average cruising airspeed velocity of an unladen European Swallow is roughly 11 meters per second, or 24 miles an hour."An African swallow or a European swallow?
style.org > Estimating the Airspeed Velocity of an Unladen Swallow