Canada experiences a wide range of seasonal temperatures throughout the regions, from -40°C in winter months to +40°C in summer. Animals have evolved various methods to cope with these extreme and varying weather conditions. Understanding these methods not only enhances our knowledge of wildlife behaviour but also underscores the importance of adapting conservation efforts to seasonal changes.
Some methods used by wildlife to deal with changing temperatures are:
-Migrating south in winter months
-Shedding in the summer and bulking up in the winter
-Hibernation
-Torpor
Figure 1. Marmot emerging from den
An alternative to hibernation in winter months is torpor, a state of reduced physiological activity. Torpor is characterized by a significant reduction in heart rate, metabolism, respiration, and body temperature (Lyman, 2013). Unlike hibernation, which lasts for extended periods, torpor can occur daily. Animals such as badgers, marmots, bats, squirrels, birds, and rodents practice torpor. During torpor, their metabolism slows down to conserve energy, reducing behavioural activity. This adaptation allows animals to survive short-term periods of cold weather or food scarcity by focusing their energy on maintaining body warmth.
Bats provide an interesting example of the use of torpor. While they do hibernate, they also enter torpor at different times of the year when temperatures drop. Bats seek out underground sites, caves, old mines, or buildings to enter this state. Torpor in bats typically occurs involuntarily during the daytime and lasts for a few hours, waking up at dusk (Lyman, 2013). This state enables them to conserve energy during periods when food is scarce or when environmental conditions are harsh. The ability to enter torpor helps bats to survive in a variety of habitats and climatic conditions.
Figure 2. A dormouse in the state of torpor (Page, 2013)
Squirrels and mice are another example of animals that use torpor. Unlike hibernation, torpor in squirrels is a lighter state of dormancy, and they can easily be awakened. This state is triggered by food shortages or lower temperature (Ruf & Geiser, 2015). Torpor allows squirrels and mice to conserve energy during periods of cold weather while still being able to forage for food when conditions are more favourable. This strategy is vital for their survival as it balances energy conservation with the need to remain active and alert.
Many species of animal are unable to migrate and for some animals, therefore torpor provides a solution for these animals to survive harsh winter conditions without leaving their ecosystems. Since torpor lasts only a few hours a day compared to the extended period of hibernation, animals can still hunt outside of their slumber. Despite their reduced behavioural activities, they manage to retain their hunting grounds, foraging areas, and shelters within familiar locations without having to migrate.
It is best to leave animals undisturbed during torpor, as interrupting this state can cause stress and disrupt their energy conservation strategies. Understanding and respecting these natural survival strategies is crucial for wildlife conservation and ensuring the well-being of various animal species throughout the changing seasons.
If you come across an injured animal, please contact the Calgary Wildlife Rehabilitation at (403) 214-1312.
References
Council, A. (n.d.). 10 facts about hummingbirds – and other interesting tidbits. Adirondack Council. https://www.adirondackcouncil.org/page/blog-139/news/10-facts-about-hummingbirds--and-other-interesting-tidbits-1101.html
Lyman, C. P. (2013). Hibernation and torpor in mammals and birds. Elsevier.
Page, M. L. (2023, ). Ultrasound can trigger a hibernation-like state in mice and rats. New Scientist. https://www.newscientist.com/article/2375650-ultrasound-can-trigger-a-hibernation-like-state-in-mice-and-rats/
Ruf, T., & Geiser, F. (2015). Daily torpor and hibernation in birds and mammals. Biological Reviews, 90(3), 891-926.
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