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.

Tuesday, November 7, 2017

Female goldfinch winter plumage

I had a particularly fluffy American Goldfinch at the window feeder and a customer thought my birds were getting too fat.

Don't worry, perching birds must maintain a healthy weight to fly away quickly. But it is chilly in Novembers so the big birds you see at the feeders might have "fluffed up" to trap air between their feathers and bodies to create a natural layer of insulation and act as a buffer from the winds and wet; think downy coat. They also can grow twice as many feathers but they still have to shiver almost constantly to increase their body temperature in cold weather.

Birds have high basal metabolic rates and therefore use energy at high rates. In cold weather, birds must operate at well above their basal metabolic rates in order to maintain their body temperatures. Small species, such as American Goldfinches that overwinter in Michigan must eat continuously during short daylight hours to stoke their metabolic fires. If they do not, they will not reserve enough energy to see them through the long night.

This is the time when a lot of high fat foods become more critical in a bird’s diet. Every night up to three-quarters of a bird’s fat reserves are used up; reserves that must be replenished the next day.

Keeping your feeders filled with high energy, high fat foods can provide your birds with the vital nutrition they need to survive. High on the list of best choices for finches are high fat seeds like sunflower seeds (429 fat calories per 100 grams) and nyjer seed (342 fat calories). Other bug eating birds birds like chickadees may prefer suet and certain seeds like peanuts, which provide 412 fat calories per 100 grams.

Related Articles:
What to feed birds in the winter http://bit.ly/tfT7Ca
Where Do Birds Go At Night? http://bit.ly/uoQOBw
How can birds survive this cold weather? http://bit.ly/uKZs6v
Food & water from bird feeders can impact birds’ survival http://bit.ly/tsnvpP

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