October is animal fattening time (Wikewiku’s)
The days are becoming shorter, the leaves more colourful and many animals are getting fatter as summer fades and autumn tightens its’ hold on the Bras d’or Lake Biosphere. In the Mi’kmaw calendar October is Wikewiku’s, or animal fattening month. This is a ‘time of plenty’ in terms of food supplies for many animals but that situation will change dramatically as the ground freezes and is then covered with a white blanket of snow. The fat that is accumulated at this time of year will sustain the animals that hibernate all winter. Hibernation is a fascinating adaptation that is necessary for the survival of many species in this climate. Some of the Biosphere’s animals remain in ‘suspended animation’ all winter and some wake up and eat during the warmer periods of winter. The little brown bat (Mi’kmaq: na’jipugtaq’nej), once common in the Biosphere, is a true hibernator, slowing down its metabolism, heart rate, and breathing. It wakes periodically to drink or eliminate waste and it relies solely on its fat reserves to survive from September to April (females) or May (males). During hibernation, a brown bat's pulse decreases from 400-700 beats per minute to 7-10. A bat will put on weight (fat) before going into hibernation, doubling or even tripling its weight! Autumn is mating season for the little flying mammals and in the past, large groups would fly in from their summer locations and gather in caves and mines to eat and mate. Sounds like a party! The population is sparse now because of the devastating effects of the white nose syndrome. The clouds of flying bats that were evident in some areas of the Biosphere in October are now gone.
Did you ever wonder what strategy the Biosphere’s chipmunks (Mi’kmaq: apalqaqamej) employ to survive during the cold winter period? In October, they are busily gathering food and storing it. When the cold days of November and December set in, they disappear below ground to their burrows. They then go into a torpid state where body temperature, rate of breathing, and rate of heartbeat drop to very low levels. Unlike the little brown bat, they don’t fatten up in autumn but store their food for occasional snacking. Periods of torpor often last from one to eight days. Between these periods, chipmunks wake up and consume part of the food supply which they stored in their burrows in the autumn. In March, when the air is warming and the maple sap is flowing, the chipmunks begin to emerge, sometimes having to burrow upwards through deep snow.
One of the more charming Biosphere hibernators is the Black bear (Mi’kmaq: Muin). Autumn is a time for them to fatten up before the long winter’s sleep. The Black bears slumber in their dens for about five to seven months without eating, drinking, urinating, or defecating. Their bodies get a little cooler but the temperature drop is not nearly as significant as it is in other hibernating animals. Their heart rates drop from 55 to 9 beats a minute. Their eyes will be open when awake but they might be groggy. If this occurred in a human, they would faint. However, the bear’s physiology is adapted to this metabolic decrease. The bear’s body essentially becomes a self-contained unit during the winter slow-down. Urine is broken down inside their body and reused as protein to help maintain muscles and a plug of faeces and hair forms at the end of the digestive tract to keep everything in. The average bear loses about 3.6 kg per week during this period, relying on those fat reserves laid down during the ‘animal fattening time’ in autumn. While the digestive tract is essentially closed, the reproductive tract remains functional.
Female Black bears often give birth during hibernation. Mother and cubs emerge from the den in the spring, none the worse for wear. To someone who has delivered three sons, this sounds like an appealing birth plan.
So, as I struggle to fit into my jeans after Thanksgiving dinner I will remind myself that my body is just preparing for hibernation as many of the Biosphere inhabitants are.
Dr. Annamarie Hatcher is an adjunct professor at Unama’ki College, Cape Breton University, and a board member of the Bras d’or Lake Biosphere Reserve Association. For more information about the Bras d’or Lake Biosphere Reserve Association, please visit http://blbra.ca/.
The hibernation cycle of the Black bear is used to explain the seasonally-changing position of the constellation Ursa Major in the Mi’kmaw legend ‘Muin and the Seven Bird Hunters’.