Since direct observation of a fossil animal's behavior isn't possible, paleontologists use comparison and contrast with living animals for guidance. Tracks can sometimes reveal further clues.
Like all bears today, presumed solitary except for females with cubs
Not adapted for fast running locomotion as often asserted in literature. (Figueirido et al 2010)
Pleistocene tracks of Arctodusmay be preserved at a site in Lakeview, Oregon.
Rather than having a waddling, pigeon-toed walking gait seen in other bears, walked with feet pointing frontward, no waddling.
A sesamoid bone in the wrist suggests some capacity for tree-climbing (and plant grasping); pandas have this adaptation.
Studies of Pleistocene Arctodus fossils from Beringia (Siberia, Alaska and the Bering Straight) indicate that competition with brown bears may have been a factor in the extinction of Arctodus. (Barnes et al 2002)
Arctodus may have competed for carcasses of hoofed animals killed by saber-toothed cats, American lions, dire wolves (Figueirido et al 2009) and possibly humans.
Barnes et al (2002)
Figueirido et al (2009)
Figueirido et al (2010)
Richards et al (2008)