About us: We own the Wild Birds Unlimited nature shop in East Lansing, Michigan,
a store that provides a wide variety of supplies to help you enjoy the birdwatching hobby.

This blog was created to answer frequently asked questions & to share nature stories and photographs.
To contribute, email me at bloubird@gmail.com.

Wednesday, December 30, 2009

Thermogenosis and Torpor (Shivering and Deep sleep)

In the winter birds can grow twice as many feathers but they still have to shiver almost constantly to increase their body temperature in cold weather. This shivering process is called thermogenosis. The constant shivering produces heat five times that of their normal rate, helping them to maintain an amazingly high body temperature.

It also burns a lot of calories. Birds store the needed calories as fat, but they can only store enough for 16 to 24 hours. This is why you’ll see birds in a panic at your feeders right before it gets dark and at first light.

Scientists have found that some birds like chickadees go one step further to survive the cold winters. The birds go into a nocturnal torpor to conserve energy. Torpor is a kind of deep sleep accompanied by drastically lowered body temperature, heart rate, and breathing. The result is a controlled hypothermia that can save a bird up to 20% of its energy. (Hibernation is defined as a sustained state of torpor).

When it’s especially cold, birds flock to feeders to build up their energy reserves. A seed blend with black oil sunflower seeds and peanuts is great to offer in the winter. It has a high calorie/ounce ratio due to its high fat and protein content. At Wild Birds Unlimited that would be our most popular WBU No-Mess Blend or WBU Choice blend.

Suet or seed blocks are great foods to offer many of the birds that will visit backyards in the winter. Suet is a high energy, pure fat substance which is invaluable in winter when insects are harder to find and birds need many more calories to keep their bodies warm. I would recommend our peanut butter suet.

Typically, your feeders serve only as a supplemental source of food for birds in your yard. However, during cold, long, severe winter weather, your birds may switch to utilizing them as the critical source of food that enables them to survive from day to day.


Vetsy said...

Thank you so much for posting this article I found it very informative and it gave me a piece of mind.

I'm so proud of myself for braving temps in the low teens just a few days ago to get black oil seed and suet...The weather was really nasty!

I worry so much about my feathered friends when the weather is unforgiving and today i have learned just how important it is to assist my little friends with high energy foods in the winter.
Thank you again for posting this Article.

Wild Birds Unlimited Mid-Michigan said...

I know. I worry too even though I know birds don't use my feeders as their main food source.

I can't feed the world but I sure try to feed my little corner of it.

Anonymous said...

Thanks for posting this informative article. I have been feeding birds on a daily basis and when the weather has turned brutal, often I see them flock to the feeder in a panic. However, Ive also noticed that they sometimes do not come for close to an hour or so. I wondered where they go, and if they are OK. I know today the weather is especially cold and the winds are gusting at 50. It is bitter cold. I will feel much more relieved when I don't see them, I'll know they're doing what they need to do to survive, and haven't fallen victim to a hungry alley cat!

I had thought they perhaps huddled together to stay warm, sharing their body heat, but your article makes so much more sense. Thank you, thank you, THANK YOU for sharing!!