At the falls, the bears take up fishing positions based on their place in the ursine pecking order. Prime spots are along the northern bank, opposite the viewing pads set aside for people. Dominance is usually determined by size, but there are exceptions. But the females know that other bears sometimes kill cubs, and fueled by maternal instincts, mothers with cubs are aggressive and will sometimes fight to the death to protect their offspring. There's often considerable tension between the bears, especially when few salmon are available.
Stress is signaled by drooling, laid-back ears, body posture and deliberate movements.
Rarely, however, does the tension lead to physical contact. For visitors watching from the viewing pad, the threat displays are ample reminder that the bears are wild carnivores equipped to kill other large mammals. Still, Aumiller believes the chances of humans being harmed, or even charged, by McNeil's bears are exceedingly small. That notion of neutrality is key to the McNeil system, which depends on what Aumiller calls benign interactions. One of the most important principles is never letting the bears associate humans with food.