Even when feeding independently, yearling bears need protection from older males, which are known to kill and eat them. This maternal instinct, when met with increased human intrusions into wilderness areas, can lead to human maulings, retaliation, and an eventual decline in bear numbers. Another cause of conflict is that competition for natural foods leads bears to discover and exploit new food sources grown by humans. In agricultural areas, stored grain, livestock, beehives, and other crops are raided. Bears in public parks develop new feeding patterns as begging or scavenging through human trash replaces their native hunting skills.
Some bears learn how to release cable-suspended food, break tree limbs, and open locked cars.
When humans are perceived as the source of food, bears may attack if they are denied the food they have come to rely upon. Learning plays a large role in a cub's ability to obtain food. Its relatively slow development and prolonged tie with its mother allow it to observe the mother's skills and to remember sites and experiences. Even the mostly herbivorous spectacled bear must learn when and where to find the most nutritious parts of plants in each season. Feeding generalists such as the omnivorous black and brown bears survive by remembering from year to year where and when to return to salmon runs, rich patches of ripe berries, and other concentrated foods important for energy reserves for hibernation.