Birds, Migration and Berries

Cedar Waxwing eat berries with its feathers fluffed up, trying to stay warm.

Mention the word “migration” to almost anybody, and it will conjure up images of mass amounts of birds flying through the air to some far-off destination for several months. That much, assuredly, is true. Nearly 1,800 of the 10,000 species of birds around the globe are classified as long-distance migrants, embarking on a seasonal journey in search of better weather and more food. What may not cross many people’s mind, however, is exactly how birds prepare to attempt such a daunting undertaking. After all, if the birds are migrating in search of more food, then where do they get food during the migration itself?

As it turns out, birds long ago solved this problem by opting instead to absolutely gorge themselves before ever setting off on their voyage. It’s been discovered, birds can eat as much as three times their body weight in berries prior to their trip. Berries being the pre-migration food of choice for many birds, even those that prefer insects during the rest of the year. Why is this, however? What would cause a bird to completely, albeit temporarily, change its diet. And not only that, but to eat so much of its new preferred food?

As can be expected, migration is a highly stressful time for all birds involved. One of the best remedies for high levels of stress is antioxidants. Conveniently, berries are loaded with antioxidants. Which is primarily why birds make the seemingly clumsy switch from insects to fruit before migrating. Although the birds may add on extra fat as a byproduct of eating nearly three times their body weight in berries—this, contrary to conventional wisdomis not the primary motivating factor. The berries are eaten to help reduce stress. Add this to a concurrent increase in the consumption of lipidswhich contain over double the amount of calories per gram than either sugars or proteins. And birds are all set for their migration, having loaded up on stress-resistant and high-energy foods beforehand.

So now the next time you see a sparrow, thrush or other clearly insect-eating bird fumbling around with some kind of berry in the fall months, you’ll have a better idea of why this curious scene happens. Happy Birding!

Written by Guest Writer Sean Peick

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  • David Wrubel August 30, 2011 at 9:48 am

    Absolutely Beautiful!! I hope to see a Cedar Waxwing sometime in my lifetime!!!

  • Betsy September 12, 2011 at 2:12 pm

    I have question about blue birds. I live in southeastern Ohio, I’ve seen a blue bird this summer in the area. Do they migrate or will it stay in this
    area? I put out a feeder with freezed dried meal worms with my other
    feeders. Should I put it away from the regular feeders? thanks

  • M. Neubecker September 15, 2011 at 4:14 pm

    Excellent article. I have seen a lot of birds eating like it won’t be here tomorrow and figured they were getting ready to migrate from northern Illinois. I’ll watch for berry eating too. Mary

  • Marcia Pavich September 23, 2011 at 9:33 am

    I have never seen a Cedar Waxwing. I live in a suburb just south of Chicago, our property is NWF certified habitat with lots of berry bearing bushes and shrubs. Our neighbors have several cherry trees which produce tempting fruit each year,non of which is sprayed for pests. the conditions would seem ideal, but no waxwings! Are we out of range? Help!!