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Refuge Notebook • Vol. 17, No. 48 • November 27, 2015

In honor of turkeys by John Morton

Simplified of the structural components used in flight. If you prefer eating at , you’re eating the ’s pectoralis and supracoracoideus muscles (credit: Wikipedia).

Did you know that you were not alone yesterday By 1601, turkeys were so common in in eating turkey? According to the National Turkey that Shakespeare wrote “contemplation makes a rare Federation, 95 percent of Americans eat turkey on turkey-cock of him: how he jets under his advanced Thanksgiving, consuming 675 million pounds from 45 plumes” in describing someone in the comedy Twelfth million . It certainly goes a long way towards ex- Night. The now fully domesticated turkey circled back plaining that gastric discomfort we experienced last to the New World when English and Dutch colonists night. Here are some facts you might not know about brought them to Virginia in the early seventeenth cen- the biology and history of turkeys. tury. , despite being the father of the mod- Turkeys were originally domesticated for their ern taxonomic naming system, incorrectly named wild , not their meat. While Aztecs did use turkeys turkeys Meleagris gallopavo because he thought they for meat and , it was their that were were related to the African (Numida me- in demand for decoration. It wasn’t until the 1900s leagris). that turkeys were selectively bred for meat produc- Our domestic turkey did NOT originate from tion, specifically for big breasts and thighs. By thelate North American wild turkeys that the Pilgrims ate 1930s, mature males reached 40 pounds with females at their first Thanksgiving. The truly amazing story weighing half that. The breast muscles are so enlarged is that the Aztecs apparently domesticated the South in commercially-bred birds that tom turkeys are inca- Mexican turkey (now a critically endangered sub- pable of getting close enough to a hen to mate—they ) over 2,000 years ago. Spanish conquistadors have to be bred by artificial insemination! Charles took it back to southern Europe and the Middle East in Darwin would roll over in his grave if he knew about the mid sixteenth century, eventually to be introduced this. to the rest of Europe by traders from Turkey (one ver- Breast muscles actually include several muscles, sion of how it got named). but the two that get the most attention are the pec-

92 USFWS Kenai National Wildlife Refuge Refuge Notebook • Vol. 17, No. 48 • November 27, 2015 toralis major and supracoracoideus. The pectoralis is transports oxygen in the blood while the former trans- what is typically called the breast and the supraco- ports and stores oxygen in muscles—and the more racoideus is the equivalent of the “ tenders” myoglobin you have, the darker the meat. Well- in turkey. In most flight-capable birds, the pectorals oxygenated muscle is needed for endurance, and so make up 15 to 25 percent of total body weight, but migratory waterfowl have dark breast meat. In con- it’s commonly over 30 percent of commercially-bred trast, most birds including domesticated turkeys turkeys. and , which don’t typically fly far, have white These two muscles make flight possible. Thepec- breast meat but dark meat in their legs as they spend a toralis stretches between the wing’s humerus and keel, lot more time running around. In fact, commercially- and is responsible for the downstroke. The supracora- bred turkeys can’t fly. coideus lies under the perctoralis and, attaching to the Not only does white and dark meat taste differ- keel and upper side of the humerus, is responsible for ently, but they cook at different temperatures. White the upstroke through a “rope and pulley” arrangement meat is best at 155 degrees whereas dark meat is best (see figure). at 180 degrees. So consider covering the breast with As you might imagine, it’s much easier to pull a an ice pack while the rest of the bird comes to room wing up since a bird is essentially falling during flight, temperature before cooking. and so the supracoracoideus is much smaller than the Lastly, many people know that Benjamin Franklin pectoralis. In most songbirds, say orange-crowned thought the should be our national bird in- warblers or gray jays that are common here on the stead of the bald eagle. But you probably didn’t know Kenai Peninsula, the weight of the supracoradoideus that in a letter to his daughter, Sarah, he wrote “For is 20 percent of the pectoralis. I have to confess I’ve in Truth the Turkey is in Comparison a much more been waiting since I first studied in 1978 respectable Bird, and withal a true original Native of to use this factoid. America. He is besides, though a little vain & silly, In contrast, the supracoracoideus of humming- a Bird of Courage, and would not hesitate to attack a birds is 50 percent of their pectoralis. This beefed-up Grenadier of the British Guards who should presume supracoracoidus is essentially what allows humming- to invade his Farm Yard with a red Coat on.”Ben would birds to not only hover, but actually fly backwards! also roll over in his grave if he discovered that the The wishbone (or furcular) is simply the fused col- commercial version of this noble bird no longer flies lar bones of the turkey. It acts like a spring to maintain or even reproduces on its own. the symmetry of wing beats as it braces the shoulders. Dr. John Morton is the supervisory biologist at And why do turkeys have white and dark meat? Kenai National Wildlife Refuge. Find more informa- It has to do with myoglobin. Avian myoglobin is sim- tion at http://www.fws.gov/refuge/kenai/ or http://www. ilar to mammalian hemoglobin except that the latter facebook.com/kenainationalwildliferefuge.

USFWS Kenai National Wildlife Refuge 93