Anti-hunters in Glastonbury, England, have launched a petition drive to keep a popular hard rock band out of its yearly music festival because its lead singer is an outspoken big game hunter and pro-gun advocate.

Activists have initiated an online petition and Facebook page seeking to ban Metallica from headlining the Glastonbury music festival because of front man James Hetfield’s outdoor pursuits. Hetfield was recently tabbed to narrate a new eight-part series on the History Channel chronicling brown bear hunting on Kodiak Island, Alaska.

So far the “Remove Metallica from Glastonbury Lineup” petition has more than 20,000 signatures, but the controversy reportedly started when festival organizers signed Metallica to showcase the concert. Many of the festivalgoers thought Metallica’s heavy metal vibe wasn’t appropriate for the more techno lineup of Arcade Fire and Kasabian — among other bands — The Telegraph reports.

But when activists got wind of Hetfield’s predilection for bear hunting and the National Rifle Association, the move to ban the band gained more steam.

Organizers “should know better than to have this barbaric idiot gracing the stage amongst a peace-loving community,” one petition-signer wrote. “I for one have already got rid of my ticket.”

The vitriol against Hetfield is the latest in a series of social media campaigns against high-profile hunters. Last year female hunter and T.V. personality Melissa Bachman faced withering fire when she posted a trophy of her lion hunt on Twitter and Facebook, and late last year, international hunting guide Corey Knowlton was hit in social media after he won a black rhino hunt in a Safari Club International raffle.

So far Metallica hasn’t officially commented on the Glastonbury backlash and it is unclear if anti-hunters will derail the band’s late June appearance.

Photo from Metallica Facebook page.