For the Birds Radio Program: Gluttony
This is the time of year when Laura thinks about gluttony, which naturally sets her to thinking about birds. (3:57)
Re-recorded in 1987
Gluttony in Birds
(Recording of a Turkey)
Studies show that Americans are as fat as we’ve ever been. But even the most gluttonous person can’t compare to a bird when it comes to how much food a body can pack away. Bird gluttony is not a pretty subject–if you’re in the middle of your breakfast, you may want to close your ears for the next few minutes. When you see a sweet little Black-and-White Warbler, do you really want to think about how it can eat 80% of its weight in grasshoppers every day? Or that woodcocks are fully capable of eating their total weight in earthworms every day?
Birds have much faster metabolic rates than mammals. The body temperature of sparrows is about 107 degrees, and some thrushes have a normal temperature of 113. Even an ostrich’s temperature is normally 104. It’s just like heating a house– the warmer you keep it, the more fuel you need, even with a high efficiency furnace. A growing bird’s digestive system extracts about 33% of its food intake as usable calories, compared to only about 10% in a growing mammal, yet, even with that high efficiency, birds need a heck of a lot of food compared to most mammals to keep going.
A pair of loons and their two chicks can consume well over a ton of fish during the fifteen weeks of the breeding season. An eight-pound brown pelican eats four pounds of fish every day. The black-footed albatross is nicknamed the “feathered pig” because it can swallow half-pound chunks of shark meat in one gulp. Turkeys eat as much as a pound of nuts or acorns in a single meal. Robins eat about 14 feet of earthworms every day. And an owl sometimes swallows so many mice or rats that its crop can’t hold them all–the tail of the last one may hang out of its beak until some of the first have been digested–not a pretty sight, even on the radio. Of course, for every night hunting is that good, there are dozens of nights when little or no food at all is taken–that’s why you never see a fat owl.
There are records of California Condors and Turkey Vultures eating so much that they couldn’t take flight. One cormorant in California died after a 10-inch fish got stuck in its throat. Right here in Duluth, observers have seen robins and Cedar Waxwings drop dead after pigging out on apple blossoms or mountain ash berries. Urban Ring-billed Gulls and pigeons often forget to look both ways before grabbing a french fry or piece of popcorn, and end up literally and permanently on the street.
Birds that hunt or fish for a living often take on prey that they would have been better off avoiding. More than one Osprey has drowned trying to pull a heavy fish out of the water. A Red-tailed Hawk in South Dakota carried off a weasel, but in mid-air the weasel got a death grip on the hawk’s throat. Six young Common Terns were found dead on Long Island in 1962 after swallowing blowfish. And at least a few Golden Eagles have died in hot pursuit of porcupine meat. One of these was preserved by a Superior man–it now rests, probably not in peace, in a display case outside UMD’s biology department, quills still in place.
All in all, birds can make the biggest Thanksgiving pig- out look like pretty mild stuff.
(Recording of a Turkey)
This is Laura Erickson, and this program has been “For the Birds.”