The funnyman plays a bird-watcher in the new comedy alongside Owen Wilson and Jack Black, and was forced to go back to nature on location in some of America's isolated national parks.
And to ensure the cast and crew's safety while filming, the movie's director David Frankel asked rangers to keep dangerous creatures at bay with the help of guns.
Frankel says, "Steve had trepidations (sic) about all the travel and exploring we had to do in the movie. He was like, 'Do we have to be in the rain and the snow?'
"We wound up shooting 2,000 miles from civilisation, and had to be protected by park rangers with rifles to ward off grizzly bears."