All bears continue to gain weight. Berries and hazelnuts become scarce. Where acorns are abundant, bears feed and fatten on them. Other bears begin losing weight. Cubs stop nursing.
Most bears enter their dens and begin a light hibernation.
Cubs born last winter will share their mother s den. A hibernating bear s heart rate slows to as low as 8 beats per minute. Breathing becomes as slow as one breath every 45 seconds. Eggs fertilized in the late spring or early summer implant in the uterus and begin to develop.