Migration and Fat

BirdNote^®  

Migration and Fat

Written by Bob Sundstrom
 
This is BirdNote.
 [Bar-tailed Godwit call]
Long-distance migration requires metabolic feats that dazzle the mind -- and lots of fat. Tiny Blackpoll Warblers double their weight in the lead-up to migration. Wilson’s Phalaropes may put on so much fat that they actually have to lose weight to get their fat-loaded bodies into the air. Chubby Bar-tailed Godwits, normally very strong fliers, may need a long running start to take off.
[A breeze blowing]
To store fat, birds may eat three times as much and forage over many more hours than normal, as they prepare for long-distance travel. To process so much chow, a bird’s stomach and intestines must physically grow in size. A bird’s liver—the organ that turns nutrients into fats—might triple in size.
At the cellular level, equally impressive changes make it possible for a bird to draw energy from all that fat during long flights. These include changes in fatty acids, plus a big bump in the protein molecules that move fats through the bloodstream. And there’s a surge in enzymes that hand off the fat to the muscles, thus fueling the strenuous work of flight.
If long migratory flights are amazing, what goes on inside a bird’s body during those flights seems absolutely astonishing.
For BirdNote, I’m Michael Stein.
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Producer: John Kessler
Executive Producer: Sallie Bodie
Editor: Ashley Ahearn
Associate Producer: Ellen Blackstone
Producer: Mark Bramhill
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Bar-tailed Godwit (Siberian), ML132119, recorded by Gerrit Vyn. Nature SFX 02 Wind, Soft, Moderate
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2020 BirdNote   June 2020       Narrator: Michael Stein

ID#  migration-27-2020-06-30   migration-27

Primary source: Cornell Laboratory of Ornithology Handbook of Bird Biology, 3rd ed., 2016.