The full moon in January is sometimes called the ‘bear moon’.  Black bear cubs are generally born in January.  The mother bear licks them clean, keeps them warm and moves into positions to make it easier for them to nurse.

All bears continue to hibernate.  Newborn cubs continue to grow as mother bears care for them.

Hibernation continues.  The testosterone (sex hormone) levels of adult male black bears begin to rise.

The snow melts and bears leave their dens.  Adult males leave their dens first while mothers with cubs are the last to leave their dens.  Food is very scarce.  Adult males begin to roam.  Most other bears remain lethargic (sluggish), eating mainly aspen catkins and willow catkins (pussy willows).  All bears lose weight at this time of year.

Green plants begin to grow and trees begin to sprout leaves.  The bears’ lethargy (sluggishness) ends.  They begin to eat sprouting grass, emerging herbs and young aspen leaves. Cubs taste what their mother eats, but swallow very little of it.  They still rely on their mother’s milk.  Mother bears that are nursing young cubs continue to lose weight.  Other bears slowly begin to gain weight.

Green plants mature and toughen, making most of them inedible for the bears. Ant pupae become abundant and bears add them to their diet.  Mating season begins and males roam widely to find females without cubs. Cubs begin eating solid food, especially ant pupae from logs their mother opens for them.  Mothers stop losing weight.  Others bears gain weight slowly.

Cherries, blueberries, serviceberries, wild sarsaparilla berries and raspberries ripen and become major foods. All bears gain weight rapidly if these berry crops are good.

Viburnum berries, dogwood berries, wild plums, hawthorn berries, mountain-ash berries, and  hazelnuts (their favorite) ripen. All bears continue to gain weight.

Acorns ripen. Berries and hazelnuts become scarce.  Where acorns are abundant, bears feed and fatten on them.  Other bears begin losing weight.  Cubs stop nursing.  Bears begin to become lethargic (sluggish) and some enter dens to begin hibernation.

Most bears enter their dens and begin a light hibernation.  Cubs born last winter will share their mother’s den.

Hibernation deepens.  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.

Hibernation continues. Cubs will sleep through their first birthday (in January) without celebrating.