From the moment Andrew Bird and Madison Cunningham started to sing and play at the Troubadour one night at the end of September, the audience listened raptly.

The occasion? One of the first full performances of the singer-songwriters’ new collaboration, the album “Cunningham Bird,” a track-by-track reimagining of “Buckingham Nicks,” the 1973 debut of Stevie Nicks and Lindsey Buckingham.

At the time, it earned the on-and-off lovers an invitation to join Fleetwood Mac, with whom Buckingham and Nicks found massive fame almost overnight in the mid-’70s. But today, the album is long out of print, almost impossible to find outside of unofficial videos on YouTube.

The original record delivered a dozen diverse songs, most of which stand the test of time. In the hands of Cunningham and Bird, it’s even more beautiful as new arrangements, harmonies and instrumentation deliver gorgeous takes on forgotten would-be classics.

Bird and Cunningham traded verses and harmonies while playing acoustic guitars — and Bird also at times whistled and played violin. They were backed by drummer Griffin Goldsmith from Dawes and keyboardist Mike Viola, who also produced the album.

The audience inside the sold-out Troubadour hardly moved as the album flowed from song to song. When Cunningham and the others paused for a few seconds of silence near the end of “Crystal,” a fan broke the silence, shouting, ‘Oh my God!,’ at the beauty of the music.

Cunningham smiled slightly before she started to sing again, playing uncommon patterns on her guitar, and with Bird whistling melody lines, they finished the song to cheers and applause.

A few days after that show, Bird talked about how he and Cunningham arrived at this unusual album, how they went about making these songs their own, and what kind of reaction they’ve received from Buckingham and Nicks for the project.

“I was just looking simply for a reason to do more live shows with Madison,” Bird says. “I just wanted to do a little tour where we play each other’s songs. And then it was suggested by a friend — they pointed out this ‘Buckingham Nicks’ album, and said, ‘You know, someone should really cover this album.’

“He explained why, you know, that it’s out of print,” Bird says. “It’s difficult to hear it and it’s a great album. And it all lined up.

“It just filtered into place,” he says. “We needed something to hang it on, to filter it through our own sensibilities. And it really surprised us how much we found in there, as far as like it’s just a fascinating sort of lost relic.”

‘We’re not a cover band’

Bird says he wasn’t particularly familiar with the record, and that Cunningham didn’t know it at all.

“It’s really a character study of two people that many people are very familiar with for everything that happened after this album,” Bird says. “And you hear in this album, if you do a deep dive, what’s to come, the good and the bad. You hear both of their distinct personalities and the worldviews often clashing at that young age.

“So we just had a lot of fun making it,” he says.

Onstage at the Troubadour, Bird had acknowledged the changes he and Cunningham had made in the original songs.

“I was looking out there thinking, I bet there are some outposts there going, hmm, I’m not so sure about these arrangements,” he told the audience. “We’re doing this with total respect for the music. We’re just not a cover band. We’ve got to do it our way.”

The original album arrived in 1973, Bird notes, “at that inflection point of the end of the hippie era, beginning of this sort of prog rock god. It very much is in that realm, but there’s a little bit of, like, Cat Stevens feel to it as well.

“It’s very dense, and I identify with that from my own early albums,” he says. “When you’re in your 20s, you just don’t know what you’re not supposed to do. You try to throw everything you’re inspired by into one album.

“The overall production style, there’s kind of an early ’70s haze, like drug den vibe to it,” Bird says. “Fleetwood Mac cleaned it up a lot. But we also ripped up the shag rug carpeting on this one and revealed the hardwood floors underneath, I guess.”

Having not grown up with “Buckingham Nicks,” Bird and Cunningham respected it without the reverence that might have made it difficult to reconstruct.

“We cleaned it up a bit in some ways rhythmically but also added our own harmonic ideas, and messed with some of the perspective on who’s singing what and to whom, genderwise. Because we both believe, like, what’s the point of covering a whole album if you’re going to feel beholden to it?”

‘An interesting pair’

Bird, who has never met Buckingham or Nicks, came to admire them more from his deep dive into the album.

“They’re an interesting pair,” he says. “He’s obviously known as a great guitar player, like virtuosic, and you hear it on this. I identify with the kind of focus it takes to be able to play your instrument that well, but then also write a fairly simple song that connects with people.

“Usually one excludes the other to some degree,” Bird says. “Like the amount of focus it takes to be a master of your instrument, sometimes you can’t see the whole picture when you’re trying to write a song. It’s kind of rare that those two come together so well.

“It’s just an interesting story,” he says of the genesis of “Buckingham Nicks.” “She was, I think, cleaning houses to support him so he could stay home and practice. Then he gets offered the gig with Fleetwood Mac and he said, ‘We’re a package. You’ve got to take Stevie too.’ She goes on to become the most successful of them all. The most iconic.”

Why “Buckingham Nicks” went out of print decades ago and has never even been released on CD remains a mystery.

“It’s all there on this album,” Bird says of the talents of its creators. “I don’t know why it’s out of print. I think it didn’t do particularly well at the time. And maybe it’s how a lot of people feel about the first thing they do. But who knows? It’s a mystery.”

The “Cunningham Bird” album, however, is not a mystery to Buckingham and Nicks, Bird says.

“They are aware of it, and no cease and desist yet,” he says, laughing. “But yeah, they’ve been cool. Lindsey’s camp has been very receptive and encouraging. And Stevie’s has been … encouraging enough.”

‘Not the last of it’

The Troubadour show Sept. 30 came a few weeks before the Oct. 18 release of “Cunningham Bird.” The group had premiered the album live at the Newport Folk Festival in July and played only a handful of other shows with it.

Bird says initial nerves about how it would be received, especially given no one had heard the whole album before the shows, eased as soon as he and Cunningham saw the audience response.

“The reception has been really good,” he says. “When you hear of someone not doing their original songs and covering something else, there’s a slight stigma against it. It would have been normal before the late ’60s and ’70s of the singer-songwriter era, where it’s like you want your singer-songwriters to have lived what they’re singing.

“I don’t know,” Bird continues. “It’s just sometimes that leads to a kind of stagnancy, of ‘This is classic and should not be touched.’ Whereas folk tradition, jazz tradition, there’s jazz standards, there’s old ballads that get done and redone hundreds and hundreds of times. Like, why shouldn’t this stuff be allowed to live in a living tradition?”

As a performer, Bird says he grows stronger through covering other artists’ songs.

“Usually what excites me about covering a song is the thought that I could turn people on to something that they haven’t heard,” he says. “Or maybe — it’s not the case with this (album) — the original version doesn’t quite capture the potential of how great the song is.

“A lot of people cover very well-known songs and they do a note for note, and I just don’t get that,” Bird says. “To me, it’s a chance to turn my own audience on to something I think is cool.

“And what I get out of it is I learn, without the pressure of it coming from your own head, you learn about how you sing,” he says. “It just brings out different things in your voice.”

A live video stream of the full Troubadour show arrives on Nugs.net at 5 p.m. Nov. 27. The HD video stream costs $9.99 and will be available to play or replay on demand through Dec. 1.

Other than that, Bird says, there aren’t many future shows planned, though he hopes he and Cunningham continue to have scattered opportunities to play the album.

“Depending on how the album’s received, it could be kind of a perennial thing,” he says. “You know, ‘Cunningham Bird’ do ‘Buckingham Nicks’ at such and such festival.

“But Madison’s off recording her new album now and I’m writing now, and we’ll see what comes up. It’s not the last of it. It’ll definitely be more.”