Severe summer drought in the Rockies severely restricts natural mast crops (berries, pine nuts, riparian roots). Observe how bears are driven down elevation corridors toward suburban boundaries in real-time.
In late summer and early autumn, American black bears (Ursus americanus) enter hyperphagia—a biological state demanding up to 20,000 calories a day to store fat before winter denning. As documented by recent reports across the Rockies, hot and parched summer conditions dry up chokecherries, buffaloberries, serviceberries, and whitebark pine seed crops. When natural mountain food disappears, calories in human developments (bird feeders, pet food, dumpsters, backyard apple trees) create irresistible olfactory lures.
When high-elevation mast production drops below ~40%, bears expand their home ranges by 200–350%, traversing steep drainages straight into foothill towns.
A single unlatched residential trash container provides an effortless 5,000 to 10,000 calories, conditioning bears to return repeatedly unless hazing or containment is active.
Certified bear-resistant trash carts and coordinated community fruit harvesting cut urban bear visits by over 60%, even during peak drought episodes.