What is the reasoning behind having the roadrunner say "beep beep" constantly? Do real roadrunner birds make a similar sound?
Chuck Jones, the creator of the Road Runner, has stated that this sound, the only way the Road Runner can harm the Coyote, was inspired by hearing a Doppler-like effect as background artist Paul Julian imitated a car horn when he could not see where he was going.
The source for this claim is a DVD commentary, in which Michael Barrier says:
Actually the title is somewhat of a misnomer; the actual 'beep beep' sound you just heard the Road Runner make was made by a background painter named Paul Julian, who used to make it in the hallways at Warner Brothers when he was carrying a large painting along, so people would get out of his way. Chuck Jones heard him make that - or Treg Brown I guess, actually, the sound effects wizard at Warner Brothers - heard him make that noise and suggested that they record that for the Road Runner, and it's been the standard Road Runner noise ever since.
Note that the sound is also spelled "meep, meep", "hmeep hmeep" or "mweep, mweep".
Real roadrunners do not go 'beep beep', or anything much like it.
Male Greater Roadrunners make a distinct co-coo-coo-coo-coooooo in a series of 3–8 downward slurring notes.
Both male and female also make a short, sharp barking call that sounds like a yipping coyote.
Both chicks and adults snap the mandibles together to make a sound like castanets. A sharp whine accompanies the clacking, with the female making a higher-pitched, more rapid sound.