USA TODAY: FIVE FEATHER-SHAKING BIG BIRD FACTS / by chad walker

For 45 years, Caroll Spinney has performed in the looming shadow of one of Sesame Street's most famous residents, the 8-foot-3 Big Bird.

Spinney, who also brings Oscar the Grouch to life on the iconic children's program, steps out of the yellow avian suit for the documentary I Am Big Bird(opening Tuesday via video on demand, Wednesday in New York and May 15 in select cities). In telling his story, Spinney, 81, reveals some amazing facts about the flightless bird named a living legend by the Library of Congress in 2000.

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He gets a hand in the height department: Much of Big Bird's immense height comes because the costume head is held in place by Spinney's lifted right hand, which also controls the eye and eyebrow expressions. Keeping the four-and-a-half-pound head upright is tiring.

"It doesn't sound like a lot until you try to hold it up over your head and perform with it for 10 minutes or more," says Spinney.

Spinney's own head is in the bird's neck, seeing the outside world on an internal monitor. He reads scripted lines with a small light, because natural light cannot make it through the costume of 6,000 yellow feathers.

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Big Bird started off goofy: When stepped into the new character's suit in 1969, the bird was a "goofy" simpleton, Spinney says. Over episodes, the bird transformed into an innocent child personality, a change he believes was crucial in the character's longevity.

"If he was still goofy, I don't think he'd be on the show. I don't see that he'd have any purpose to be there," says Spinney. "When he became a child, he was a kid who was embodying the stories and feelings of Sesame Street."

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Big Bird was supposed to be aboard the doomed Challenger: NASA officials envisioned bringing Big Bird onboard the Space Shuttle Challenger to drum up youth interest in the mission. But the concept was scrapped because the costume was too big to fit into the spacecraft.

Spinney watched the 1986 liftoff from the Sesame Street set. An explosion seconds into flight killed all seven crew members.

"When I saw that happen, I thought, 'I was supposed to be on that ship,' " says Spinney. "And the horror of knowing that these people died. It was terrible." 

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Mitt Romney gave Big Bird's popularity a huge boost: The Republican presidential candidate invoked Big Bird's name when decrying PBS funding during a 2012 debate with Barack Obama. The move backfired on Romney as support galvanized around PBS and the bird. It even led to a first-time appearance on Saturday Night Live.

"It was pretty nice," says Spinney. "I have to thank Mr. Romney."

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There's no Elmo competition: A new generation of Sesame Street fans have gravitated toward falsetto-voiced Elmo. But there's no Muppet jealousy on the set.

"I am happy to share," says Spinney, who has no plans for retiring, especially with his beloved character getting more screen time. "Big Bird is even having something of a resurgence on the show."