Caroll Spinney, left, gets assistance with his Big Bird costume from “Sesame Street” puppeteer Kermit Love. (Debra Spinney/Tribeca Film)

The documentary “I Am Big Bird: The Caroll Spinney Story” is as bright and fluffy as the canary-yellow feathers that bedeck the titular “Sesame Street” character. Unsurprisingly, there isn’t much of an edge to this sunny and affectionate portrait, save for a brief mention of the cobra- and mongoose-like rivalry that has developed in recent years between this 8-foot-tall avian Pollyanna and Elmo, his Muppet rival, for the affections of America’s 3-year-olds.

Like the 2011 documentary “Being Elmo: A Puppeteer’s Journey,” which profiled Kevin Clash, the “Sesame Street” veteran who plays Elmo, “Big Bird” deals with the man behind — or, in this case, inside — the puppet. The 81-year-old Spinney, who has been playing Big Bird since Jim Henson discovered him at a Salt Lake City puppet festival in 1969, comes across as preternaturally cheerful, even considering what he describes as a brief flirtation with suicide, around the time of his painful 1971 divorce from his first wife, Janice. Since 1979, Spinney has been married to his second wife, Debbie, and the two still seem almost cloyingly in love, as one relative observes.

Aside from the contemplation of suicide, there’s little sour to temper the sweetness of this portrait. The discussion of Spinney’s sometimes fractious relationship with the late “Sesame Street” director Jon Stone (1931-1997) feels forced, as though directors Dave LaMattina and Chad N. Walker were fishing for something to give the film a little texture or grit.

But does anyone really want to see that?

The film is most interesting when it looks at the technology behind the artistry. When we see how Spinney works — with his left hand operating Big Bird’s mouth, his pinky flicking the eyelids up and down, and his right hand flapping the right wing, all inside a suit that’s as hot as a down jacket — it’s no wonder that, at Spinney’s age, Big Bird seems to be walking with a bit of a stoop in his neck these days.

No matter, the film reassures us. Big Bird will go on. Spinney’s apprentice, Matt Vogel, (whose last name means “bird” in German) has been waiting in the wings — pun intended — for more than 15 years to take over the famous role, whenever his mentor retires.

Unrated. At the AFI Silver Theatre. Contains brief crude language.
90 minutes.