Katmai’s Brown Bear Births And Spring Cubs
by Ranger Masaki Mizushima, Katmai National Park
If you happen to be a Park Ranger at Brooks Camp in Katmai National Park, an inescapable question asked by most visitors and pondered by all is, “Where are the mothers with cubs?” Immediately the five to ten bears playing, chasing each other, mating, or simply wandering around in view, vanish from one’s mind. The magnanimous muscle of hefty boars obsessively fishing, or fighting with gusto to defend their prized fishing holes at Brooks Falls in July, is quickly overlooked. What tends to grab our attentions the most are those adorable little balls of fluff that are cubs – the underdogs of the brown bear world – whose presence becomes the peak experience of most who have spent time at Brooks Camp.
Throughout the unyielding freeze and storms of Alaska’s winters, brown bears are snuggled tight in their snow-insulated dens. However, those who became pregnant before denning will be giving birth by late January and early February. As the chill of winter’s gales grate the exterior mountain slopes, within each dark, bear-sized den, new life begins. As a contrast to the pains a human mother undergoes during childbirth, brown bears are still in a hibernating state, allowing the birthing of their cubs to be less of an ordeal. Since the fertilized egg(s) does not implant against a female’s uterine wall until October (the process of delayed implantation) the cubs will be born in three to four months. They emerge from their mother cold, hungry, vulnerable. At first glance, a newborn cub may look somewhat like a bald weasel or squirrel – furless, blind, toothless, about nine inches in length, and weighing little more than one pound. Instinct and assistance from their mother protects each cub as they feel the warmth radiating from her body, struggling as they crawl towards her, and begin nursing from her teats. A pregnant mother’s fat reserves were obtained and accrued for this moment, to outlast the duration of winter. Averaging two to three cubs at birth, much of a mother’s fat is converted into a high-protein, creamy, white milk, containing a fat content of about 18 percent. Feasting on this life source, cubs greedily consume every drop their mother allows, causing a cacophony of loud bawling and guttural purring.
By the time Alaska’s winter reign is ended over the Katmai wilderness, the regime of spring approaches, signifying the upcoming emergence of brown bears from their lengthy slumber. Those helpless cubs born under spartan conditions are not as defenseless anymore. They will have grown a dense fur layer for warmth and protection from Alaska’s dynamic climes and copious, pesky bugs. Deadly teeth and claws sharp enough to shred a five pound salmon in mere seconds will have developed since their births. In three months’ time, a cub will increase its bulk and size, gaining an average of 20 to 25 pounds! Yet, as tiny, furry, brown bear heads poke out of dens, in tow behind the protection of their mother, the entire world is new, mysterious, and unknown. Everything, the call of a tundra swan overhead, the sound of pumice stones washing ashore along the beach, the site of brown bears larger than their mothers, will instill a mixture of caution and curiosity within each new spring cub or coy (cub of the year).
Although brown bear behavior is scarcely observed during Katmai’s lengthy, dark, and remote winters, the ongoing lives of these bears is evidenced as the seasons change and spring arrives. As the brown bears sluggishly descend the mountain sides of Katmai National Park, Park Rangers will be the first to arrive at Brooks Camp preparing its facilities for visitors in the upcoming season – all the while wondering and asking the questions, “Which sows will have given birth?”, “How many cubs will we see this summer?”, and the prevalent, “Where are the mothers with cubs?”
