WELLESLEY - What does it mean to be a true friend?

“Birdy,” presented by Commonwealth Shakespeare Company and on stage at the Carling-Sorenson Center at Babson College, plants this question in our heads with an intimate, visceral portrait exploring the covenant of friendship.

Adapted from William Wharton’s debut 1978 novel, the drama by playwright Naomi Wallace is deftly directed by Steven Maler, artist director of Commonwealth Shakespeare Company and produced by Spring Sirkin. It was also made into a 1984 film, directed by Alan Parker, and set in the Vietnam era, that starred Matthew Modine and Nicholas Cage. The play moves back and forth in time throughout, and four actors play the two characters, Birdy and his friend Al.

Excitable and young Birdy (Spencer Hamp) loves to collect and feed the pigeons and canaries on the rooftop of his home. For Birdy, shy and socially awkward, his feathered friends aren’t just a hobby, they are all-consuming. Young Al (Maxim Chumov) knows his friend’s obsession is a little weird but gladly supports Birdy’s experiments to imitate bird flight by helping him test a contraption that uses old aluminum blinds for wings and a bicycle to obtain the required speed to achieve liftoff.

The set - three soaring stages of metal scaffolding covered with old rusty bed frames, piano innards, an industrial fan, a bird coop, venetian blinds and other detritus - gives the feeling of an alley in the boys’ neighborhood on the outskirts of Philadelphia. The actors climb up the scaffolding to visit the birds on the rooftop and use it for their launchpad.

The two grow older and in high school Al tries to get Birdy to go to the prom with a girl, and while he reluctantly agrees, it is clear Birdy has no interest in girls. Al crudely explains sexual attraction to Birdy but the whole thing is lost on Birdy, who relates the whole thing weirdly to his avian friends.

Birdy learns to warble and whistle and tells us he wishes he were a bird. He goes so far as to feed his favorite, Perda, by putting seeds in his mouth and feeding it to her like a mother bird. When he’s alone he reveals to us his unnatural obsession has taken him over the edge, foreshadowing things to come.

Al, though he is more socially adept, also has a secret. His father has been beating him at home, which Birdy discovers when he sees the bruises on Al’s back. Birdy wants to call the police but Al makes him promise to do nothing, intensifying their bond by keeping it under wraps.

The audience is seated close around the edges of the stage, making it impossible for us not to see and feel the characters’ visceral emotions during the boys’ various adventures, some that take them near death. This seating arrangement must limit attendance but having the chance to be so close to the actors is a treat.

After high school, the adult Al (played by Keith White) and adult Birdy (Will Taylor) go off to fight in World War II but in different units, with disastrous results. Al gets court marshaled after hitting an officer and nearly gets kicked out of the Army. Birdy, however, bears the brunt of their separation when he’s sent overseas and his platoon is annihilated. His mind broken, he has been shipped back home to a psychiatric hospital in Kentucky where we find Dr. White (Steven Barkhimer) is charged with bringing him back to health but is cruel in his frustration.

Al, who’s been brought in to try to help Birdy as a last resort by Dr. White, finds his friend has completely retreated and is no longer the boy he knew but has turned into a mute, a bird-like creature who crouches on his toes and wraps his arms around himself as if he were hiding under wings.

Renaldi (Damon Singletary), a conscientious objector who’s working as a nurse in the hospital, is a bridge between Birdy and Al and is certainly kinder to Birdy than the doctor but there’s no change in Birdy’s condition and no one can even get him to eat. The tension in Taylor’s bird-like movements as he bends and balances on the tips of his toes is like watching a man on the high-wire. His bird-like stare, unseeing of the humans around him, show us Birdy has retreated to his own world.

Keith White as the adult Al has most of the dialogue and takes us deep into the emotional story. Barkhimer’s White seems to be representative of the nation’s attitude toward psychiatry at the time and we thank God things have changed since the 1940s.

Al is at a loss as to how to help his friend and seems to finally accept that Birdy is a lost cause when he suddenly drops all pretenses, takes some porridge into his own mouth and feeds it to his friend like a mother would a baby bird. He does what needs to be done for Birdy, like a mother would for a child.

So what does it mean to be a great friend? A recent Facebook post I saw read: “A true friend is somebody who knows how crazy you are and is still willing to be seen with you in public.” “Birdy” takes us beyond that idea and shows us a portrait of one who’s willing to go above and beyond, giving all of himself.

Nancy Olesin is a Daily News Staff writer. Follow her on Twitter @WickedLocalArts.