Winter isolation is nothing new for the members of Trampled By Turtles, but recording sessions for the innovative string band’s new album, Wild Animals, were beset with an additional challenges beyond the hard work of crafting new songs. While holed up last January in their home state of Minnesota at Pachyderm Studio—the place where Nirvana made In Utero—members of the quintet started passing around the flu.

Despite fighting contagious illness, the group managed to craft the most sonically stimulating album in its decade-long run.

“I think the fever brought something out in the playing,” says banjo player Dave Caroll, who was one of the flu-stricken. “Sometimes when you’re sick, you’re in a different state of mind, and good things can come out of that.”

Trampled By Turtles formed in the small North Country city of Duluth back in 2003 and, like most independent bands, earned its audience with relentless road slogging. While armed like a back-porch bluegrass outfit, the band’s sound is hardly traditional. The group is in fact best known for pouncing on its strings with reckless abandon, riling up crowds with a punk ethos on acoustic instruments. But juxtaposing the foot-stomping rowdiness are introspective quiet songs, delivered through rustic aching vocals by band frontman and main songwriter Dave Simonett.

On Wild Animals, the band leans on mellow material, crafting an effort that mixes experimental folk with primal pop instincts. Lead single “Are You Behind the Shining Star?” (performed by the band on the Late Show with David Letterman in July) shines with a sweet hook and vintage Wall of Sound glaze, but deep within Simonett’s lyrics is an emotional isolation in tune with the late Townes Van Zandt.

The theme runs through the group’s latest and seventh studio release, as Simonett, who relocated from Duluth to Minneapolis, grapples with missing the more remote setting of his former home. “Solitary time in a nearly untouched landscape is my version of church, so I think there is a bit of loss of religion in a lot of my work these days,” Simonett said in a release about the new album. “I’ve always been a little obsessed with our struggle to stay connected to our simple animal side, the part of our nature that lived off the earth, hunted live game, worshipped trees and mountains.”

The sentiment is felt right away in the opening title track, which flows with an ethereal, cinematic shiver. The mood can be attributed to producer Alan Sparhawk. Best known as a member of longstanding indie rock outfit Low, Sparhawk helped push the Trampled members beyond the conventions of their strings.

Fresh off a sellout of Colorado’s venerable Red Rocks Amphitheatre, the group is heading to the South this month with stops at the Bijou Theatre in Knoxville, Tenn., on September 7 and the Jefferson Theater in Charlottesville, Va., on September 9.

In planning set lists, Caroll says the band is careful to mix in the new material with more aggressive old favorites.

“The slow songs can allow us to explore our instruments a little bit more,” he says. “There’s not as much going on, so subtle elements can go a long way. But we’ve learned how to gauge a crowd and know when they’re looking to get rowdy.”