Black-capped chickadees, chestnut-backed chickadees and mountain chickadees spend the winter in the Kimberley Nature Park. Have you ever wondered how these little birds survive our harsh winter weather?
Chickadees eat insects, berries, and seeds for much of the year, and they have beaks that are well-adapted to cracking oil- and energy-rich conifer seeds, their main winter food. They have even been seen eating energy-rich fat from animal carcasses opened up by predators and scavengers. This diet allows chickadees to add body fat amounting to 10 percent of their weight each day, and to use it up each night to generate heat. On the human scale, imagine if you gained five to 10 kilograms during the day -- and then lost it all each night!
In times of plenty chickadees cache food, and for up to 28 days they are able to remember both the location of the food and its energy content. During cold winter months, when high-energy foods are needed, the birds return to the places where they cached the foods highest in energy.
During the breeding season chickadees live as breeding pairs, but in winter they are very social. This social behaviour extends to communal nesting in logs or nest boxes in winter, which allows them to save energy. In extremely cold conditions, chickadees can lower their metabolic rate at night, decreasing their body temperature by as much as 10 °C. They therefore lose less heat, and this also conserves energy.
Any outdoorsperson knows that to avoid hypothermia you need to stay dry. Chickadees, like all other birds, have a preen gland located near the base of their tail. They use their beaks to spread this oil over their feathers (the feet are used to reach the head), and this maintains water repellency. But how do they produce enough heat to stay warm in the winter?
Chickadees repeatedly flex their pectoral muscles (shiver) to generate heat, which is then trapped by up to 2.5 cm of fluffed up feathers which are excellent insulators and which hide the fact that they are shivering.
Chickadees survive our cold winters by adjusting their diet, behaviour, and metabolism. They are indeed amazing little birds.
For more information on the flora and fauna in the Kimberley Nature Park, check out the Nature Notes posters on our website at https://www.kimberleynaturepark.ca/posters
Photos by Lyle Grisedale