“… the metabolic equivalent would be to run 4-minute miles for 80 hours …”
This is from Ornithology, Third Edition by Frank B. Gill (2007):
… Every fall, vast numbers of migrants leave coastal New England and Canada, heading southeast over the Atlantic Ocean. The capacity for such flights by larger, faster shorebirds such as the American Golden Plover has been known for many years. Radar studies now reveal similar efforts by millions of small land birds.
[line break added] As many as 12 million birds pass over Cape Cod in one night, embarking on a nonstop journey of 80 to 90 hours. Wave after wave of the migrants, such as the Blackpoll Warbler, pass Bermuda. Farther on, they encounter strong trade winds from the northeast. The migrants then fly with the wind southwest toward the northern coast of South America.
Tim and Janet Williams put this feat in perspective: “The trip … requires a degree of exertion not matched by any other vertebrate. For a man, the metabolic equivalent would be to run 4-minute miles for 80 hours …. If a Blackpoll Warbler burned gasoline for fuel instead of its reserves of body fat, it could boast of getting 720,000 miles to the gallon!”
Evidence of the strenuous nature of the trip can be seen in the exhausted condition of birds that stop at Curaçao, short of their destination, when flight conditions have been poor. Little more than feathered skeletons, they have depleted their fat reserves, metabolized much of their protein, and drained the remnants of this precious body water.
My most recent previous post from Gill’s book is here.
-Julie
Coloring 