What is the most reliable field characteristic to differentiate a Grizzly Bear from an American Black Bear?
Answer
The presence of a prominent shoulder hump
The presence or absence of a distinctive hump over the shoulders is the most reliable way to distinguish grizzlies (which have one) from black bears (which lack one).

Related Questions
What term describes the flat-footed walking posture characteristic of bears, placing their entire sole on the ground?What is the most reliable field characteristic to differentiate a Grizzly Bear from an American Black Bear?Compared to grizzlies, what specialized function are the black bear's relatively shorter, more curved claws adapted for?Despite their white appearance, what color is the skin of a Polar Bear?What specific physical modification allows the Giant Panda to effectively grip bamboo stalks?How is the facial profile of a Grizzly Bear typically described in contrast to a Black Bear?For what primary activity are the long, curved claws common to many bears chiefly optimized?What is the grizzly bear's prominent shoulder hump actually composed of?What maximum speed can bears reach in short bursts of running?What feature of the Polar Bear's massive paws assists in their powerful swimming ability?