Left to right: Cellist Alexis Hawks, vocalist Terry McCants, and guitarist-vocalist David Stockhausen of Spurs play with Marty O’Reilly at the Tannery on New Year’s Eve.

David Stockhausen didn’t know something had been missing from his folk-rock band Spurs until it was already there. When Alexis Hawks, a cello player, joined the band, he instantly understood what she brought to the group’s Western-tinged ballads.

“When I first heard it, I was like, ‘Whoa, that’s the emotional depth I’m looking for,” says the acoustic guitarist and singer Stockhausen. “The cello is a perfect marriage with the songs I’ve written. I didn’t realize it ’til I heard it.”

Higher in pitch and more melodic than a bass, the cello lies low when Stockhausen’s steady rock rhythms and singing take center stage, and then shines— sometimes even soloing—in between verses and when Stockhausen picks his guitar more gently. Hawks’ cello moans in a mournful drone against the harder faster notes of the band’s other instruments.

“The music has a drive and a rhythm, and David and I are often with each other,” says Terry McCants, the other vocalist in what used to be a duo. “[The cello] expands the music sonically and provides another melody.”

I’m sitting on a twin bed and eating ginger snaps freshly baked by Stockhausen’s wife Jade Giotta in their Felton home, where I’ve invited myself to watch a Spurs practice session. McCants is sitting to the left of Stockhausen and Hawks to his right. Also here are upright bassist Jeff Kissell—on loan from Marty O’Reilly and the Old Soul Orchestra—and Mike Owens, the Spurs’ new drummer. On some tunes, Stockhausen has Owens playing just behind the beat, tying the songs loosely and lazily together to give them a relaxed feel.

The band is rehearsing for their New Years Eve show at the Tannery Arts Center, where they’ll take the stage before O’Reilly. The Spurs are using the show as a release party for their new CD. Ironically, the seven-track album has cello on only one song, a romantic make-up ballad called “Wounds,” because Stockhausen started recording last spring—Hawks joined more recently.

Stockhausen and McCants have been friends since 2002, when they lived together in Vermont. At the time, Stockhausen was drumming in a few bands, including one called the Middle Eight, which was trying to get famous as a pop group. (Stockhausen accidentally broke up the band when he decided he “hated the music” and didn’t want to move to Chicago with them.) It wasn’t until Stockhausen moved to Santa Cruz in 2011 for a job as a farm supervisor at the Homeless Garden Project that he reunited with McCants, who had been living here since 2005.

By the time they hung out again, Stockhausen, also a personal chef, had switched to playing acoustic guitar, and McCants—a native of Texas—impressed him with her ability to sing natural harmonies on old country songs. They started playing together as the Silver Spurs, a honkytonk country band, in 2012, but the cover songs they were singing started feeling stale. McCants suggested they instead try Stockhausen’s originals, many of which are slow and have a lot of natural imagery. “I’ve always loved the wilderness,” Stockhausen says, “so that’s where I often find a metaphor that makes sense to me.”

Then earlier this year, McCants was sitting at Caffe Pergolesi when a friend sat down next her. It was Hawks. “I’ve got a lot to do today, man” McCants told her. They started talking, and McCants let Hawks have a listen to some of the Spurs’ songs. Hawks offered to bring her cello and sit in with Stockhausen and McCants on a few tunes. “But we were like, ‘no,’” McCants recalls. “‘Basically, ‘join the band.’”

Hawks and Stockhausen suggest cellos might be uncommon in folk and rock songs because where a violin has a high tenor sound to contrast with vocals, a cello’s tambour and range are similar to those of a human voice.

“It’s such a cool instrument, though,” Stockhausen says. “Sometimes I wonder if it’s the actual songs that are drawing people to be interested in us or if it’s the novelty of what Alexis brings. People did come to see us before she was in the band, so I’ve got to think some of it is song-related, and the fact that we sing harmony. Now that I’ve heard Alexis with us, and I’ve grown accustomed to the cello, I would feel super naked without her.”

The Spurs play Tue Dec. 31 at 8pm at the Tannery Arts Center; $20 adv/$25.