Cyrus the magpie is Thelma Thumb's sidekick and friend in the recurring Sesame Street animated inserts. His function, according to story notes when planning the series, was to either create the segment's problem or to report it to the audience.
Cyrus debuted in the pilot short "Magpie," with a slightly different design. Thelma rescues a yellow bird (not yet named) from a petshop cage and the attacks of a cat. The bird recalls how he was attacked by a monster, actually a street-painting truck which turned him yellow and left a black bird outline on the street. The magpie received his permanent color and name in the second segment, "Binoculars." In a later segment, "Picnic," Cyrus unintentionally threatens a diminutive Thelma Thumb by eating the potato chips used by the ant community as amusement park rides.