The Little Blue Heron’s Color Swap
When young, the birds are white, but by the time they reach adulthood, they become dark blue. Why?
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Transcript:
This is BirdNote.
Two herons鈥攐ne dark, the other white鈥攆eed at the edge of a wooded pond in the South. The dark bird has a blue-gray body and red-violet neck. The other is pure white. Yet both birds are Little Blue Herons. What鈥檚 going on here? Why the color change?
Well, the white bird is a juvenile. These young herons benefit from foraging with flocks of Snowy Egrets, which stir up prey. The white immatures mix readily with the white egrets and, by this mimicry, gain a better chance of getting a meal.
The dark birds are adult herons, toward which Snowy Egrets are aggressive. Dark herons, in general, tend to be solitary and quite aggressive even to each other. By arraying the immature Little Blue Heron in white, nature helps the young bird survive the vulnerable early years of its life.
You can find photographs of Little Blue Herons in both light and dark plumage on our website, birdnote.org. Get BirdNote whenever you want when you sign up for our podcast at BirdNote.org. I'm Michael Stein.
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Credits:
Written by Ellen Blackstone
Producer: John Kessler
Executive Producer: Chris Peterson
Narrator: Michael Stein
Sounds of birds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Calls of Little Blue Heron 134186 recorded by M.J. Fischer; feeding (water) sounds from track on Snowy Egrets 59443 recorded by W.W. H. Gunn; ambient from Snowy Egrets track.
漏 2014 Tune In to Nature.org March 2017/2019