What is Happening to our Hibernators?

2022-09-21

 |  Biodiversity/Conservation

The effects of climate change this summer have created scorching hot temperatures that have left us hiding in air-conditioned rooms and downing iced drinks. Climate change has shaped the variability and predictability of our weather that have in turn impacted the behaviours and habitats of our hibernating animals in Canada. West Coast provinces, such as British Columbia and Alberta, have been facing warmer and warmer winters each year. This has negative impacts on animal reproduction, survival, habitat, human conflict, and food, dramatically threatening our fragile ecological system and the resilience of our animal populations.

Hibernation and its Role in the Environment

Hibernation is when animals undergo a seasonal dormancy during the cold, winter months that is characterized by metabolic depression, a drop in body temperature and minimal activity. This allows them to conserve energy that enables them to survive the extreme weather and the lack of available food. Therefore, the months before the winter are crucial to hibernating animals, as they eat many times their body weight to accumulate enough fat to survive the winter. 

There are three types of hibernation; true hibernation, brumation and torpor. True hibernation, done by groundhogs, is where the animal does not wake up at all, even if there is a loud noise or if they are being moved or touched. Brumation is a hibernation state done by cold-blooded animals like Blanding’s turtles and Northern Leopard frogs, where they are able to wake up to drink water before going back to sleep. Torpor, done by grizzly bears or striped skunks, is a light hibernation that lasts a couple days as animals can wake up on warmer winter days. 

Weather on the West Coast 

The West Coast’s climate has been getting less harsh by having warmer temperatures that bring more rainfall and less snowfall. In fact, reports say that Canada is warming twice as fast as the rest of the world with warming happening even faster in the winter. 

Impact 1: Reproduction – Grizzly Bears (Torpor hibernation)

The warming fall and winter temperatures are speeding up the development and timing of seasonal fruit and vegetables in the extratropical regions of Earth. To prepare for hibernation, grizzly bears in the Alberta Rocky Mountains gorge on the Canada buffaloberry instead of the Salmon as they are landlocked, but warming temperatures have pushed the berries to ripen three weeks earlier than they used to. This alters plant-animal interactions and risks trophic asynchrony, harmful changes in the timing of ecological interactions, as these changes widen the gap between when bears have their berry feast and when they go into hibernation. This endangers them as it may force bears to go into new areas in search for food, provoking more ecological changes, and it may compromise their ability to reproduce as they would not have accumulated enough fat reserves in order to do so.

Impact 2: Survival, Predation and Habitat Changes – Ground Squirrels (Torpor hibernation)

Hibernation has shown to increase survival in hibernating animals as inactivity reduces predation. One study found that hibernators, like ground squirrels, have around a 15% higher chance of annual survival compared to similar non-hibernating animals: a small mammal was calculated to be five times more likely to die each month in the active season than during hibernation. Ground squirrels determine when to exit hibernation from the amount of snow cover around their burrow, so less snow from the warmer winters means they exit hibernation earlier. This reduces the amount of time ground squirrels spend in hibernation, therefore exposing them to more dangers and predation, reducing their lifespan and reproduction. Reduced snow cover from warmer winters can also threaten ground squirrel populations during hibernation as it removes a layer of protection against predators, like the badger that dig these squirrels up. 

Impact 3: Human Conflict – Black Bears (Torpor hibernation)

Warming temperatures were also found to shape black bear hibernation patterns and behaviour, as it reduces the length of the hibernation period, therefore raising the amount of black bears that are around during the year and increasing the chance that they run into a human. This is a crucial problem currently faced by many conservation and management organisations in National Parks across Canada and the United States. Conservation officers in British Columbia have to kill up to 1000 black bears every year due to serious incidents of human-bear conflict. Conflict increases from irresponsible waste management and improperly handled garbage, as their strong sense of smell makes the bears wander into human areas like campgrounds. A longer active season from climate change increases the chances of humans and bears meeting due to these conditions, and therefore increases the number of black bears that may be eliminated by BC conservation officers. 

Impact 4: Food Scarcity – Marmots (True hibernation)

Marmots are also emerging from hibernation earlier than they did a few decades ago, even if there is snow still outside. This snow, however, limits their food possibilities as there are no plants for the marmots to eat when they emerge. They must use their leftover food reserves whilst being euthermic, a state where animals produce warmth and body heat, but this can be stressful for the marmots if the interval between emergence and the start of the flora growing season is too long due to the costs of having a high body temperature and metabolism. This can put marmots at risk of starvation. 

Our environment is a vast, interdependent system and it’s important we protect it, not only for our own future but also for the future of our animals. These discoveries and studies about the impacts of warming winters on hibernation are recent, as there are still many unknowns on the repercussions these four impacts can have on other fauna, flora and humans. Whilst this message is mentioned often, it’s crucial we take steps to reduce our carbon footprint to decrease, and hopefully reverse, the warming of our winters and the planet as a whole.

References 

https://www.nationalgeographic.com/animals/article/hibernation-birds-mammal-fall-autumn

https://www.nature.com/articles/s41558-019-0454-4

https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2010.02165.x

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3177628/

https://onlinelibrary-wiley-com.proxy3.library.mcgill.ca/doi/full/10.1111/brv.12105?sid=worldcat.org

https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.13021

https://www.env.gov.bc.ca/wld/documents/blackbear.pdf

https://www.pnas.org/doi/10.1073/pnas.97.4.1630?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed

Photos

https://www.mentalfloss.com/article/531450/facts-about-grizzly-bears

https://www.rmotoday.com/banff/grounds-squirrels-relocated-from-banff-cemeteries-4869538