“Is it too real for ya?” blares in the background of Andrea Arnold’s latest film, “Bird,” a 12-year-old Bailey (Nykiya Adams) rides with her shirtless, tattoo-covered dad, Bug (Barry Keoghan), on his electric scooter past scenes of poverty in working-class Kent.

The song’s question — courtesy of the Irish post-punk band Fontains D.C. — is an acute one for “Bird.” Arnold’s films ( “American Honey,” “Fish Tank”) are rigorous in their gritty naturalism. Her fiction films — this is her first in eight years — tend toward bleak, hand-held verité in rough-and-tumble real-world locations. Her last film, “Cow,” documented a mother cow separated from her calf on a dairy farm.

Arnold specializes in capturing souls, human and otherwise, in soulless environments. A dream of something more is tantalizing just out of reach. In “American Honey,” peace comes to Star (Sasha Lane) only when she submerges underwater.

In “Bird,” though, this sense of otherworldly possibility is made flesh, or at least feathery. After a confusing night, Bailey awakens in a field where she encounters a strange figure in a skirt ( Franz Rogowski ) who arrives, like Mary Poppins, with a gust a wind. His name, he says, is Bird. He has a soft sweetness that doesn’t otherwise exist in Bailey’s hardscrabble and chaotic life.

She’s skeptical of him at first, but he keeps lurking about, hovering gull-like on rooftops. He cranes his neck now and again like he’s watching out for Bailey. And he does watch out for her, helping Bailey through a hard coming of age: the abusive boyfriend (James Nelson-Joyce) of her mother (Jasmine Jobson); her half brother (Jason Buda) slipping into vigilante violence; her father marrying a new girlfriend.

The introduction of surrealism has the ironic effect of breaking the spell that has marked Arnold’s best films. “Bird,” which opens in theaters Friday, is, like the writer-director’s vivid previous work, a movie only she could make. Arnold has described it as the hardest thing she’s ever created, and it’s easy to applaud her for grasping at something in “Bird” that ultimately is just out of reach. A resolutely realistic filmmaker turning to magical realism has the uncomfortable effect of making the whole movie, not just the Rogowski bits, feel inauthentic. Instead of being “too real for ya,” “Bird,” with its in-your-face poverty and narrative extremes, never feels particularly real at all.

The most incongruous parts of “Bird,” though, might not be the mysterious avian friend. (Rogowski, a compelling performer, only ever feels half in the movie, as if “Bird” can’t quite commit to him being there, either.) Keoghan is a reliably arresting actor who here feels out of place.

He doesn’t seem even vaguely fatherly, and while that might be part of the point, too many other things about Bug feel more performative than genuine.

There’s his scheme to use hallucinogenic slime from a toad to pay for his wedding, for starters. Add in some karaoke scenes and the sensation creeps in that “Bird” is being less compelled by its own story than it is by a pursuit of Arnold’s previous style.

“Bird” may go down as a rare miss for Arnold but you can still see the keenness of her eye and the nimbleness of her camera, with her regular cinematographer Robbie Ryan. And that’s true never so much as when the camera is on Adams, a talent, whose melancholy eyes say more than all the theatrics around her.