As Thanksgiving approaches, many of us look forward to the singular experience of carving a turkey. Knowing some basic bird biology will enrich your experience.
Some folks would rather not eat birds. Good for them. And good for the environment. The rest of this column, however, is designed for those who can relate to my former roommate in grad school. When he learned his new roommate studied the biology of birds, he licked his lips and replied, “I like birds, too — chicken, turkey, duck, pheasant, dove…”
So, if you plan to dissect a turkey this Thanksgiving, here is the biology that will help you understand your bird at a deeper level.
When you eat meat, you are eating the muscles of an animal. Dark and white meat represent two kinds of muscle. You will find dark meat muscle in turkey legs, where it gets used for sustained activity. White meat muscle is found in the turkey breast and wings, where it gets used for short bursts of activity.
To understand how this works at a deeper level, we need to know a little more about how cells convert food into energy. The first method, aerobic respiration, produces 18 times as much energy, but it requires oxygen and is comparatively slow. The second method, anaerobic respiration, produces much less energy, but it is lightning fast and requires no oxygen.
Let’s pretend you are a turkey. You and your baby poults spend all day on your feet, walking around. To support all this walking, your legs are loaded with dark meat muscle. The reddish color of your leg meat results from a red-colored protein called myoglobin. This protein accumulates oxygen delivered to the muscle by extra blood vessels. The ongoing supply of oxygen means your leg muscles will churn through aerobic respiration all day long. Energy galore.
But wait! A terrifying, bright orange hunter appears from nowhere. There is no time to store up oxygen in your wing muscles. You immediately flush, flapping your wings like crazy using the instant energy provided by anaerobic respiration. Then you crash back into a bush, exhausted.
Getting that fat turkey body of yours off the ground could not have happened without a few biological adaptations. The white meat muscle is just the beginning. You also needed some impressively large breast muscles to provide power.
Massive muscles need massive bones to serve as their anchors. If your turkey breastbone were flat like those funny human breastbones, then your large breast muscles would have only minimal space for anchoring. Thanksgiving chefs will notice after cutting through a lot of breast meat that turkey breastbones have a sail-like projection on top. This ‘keeled’ breastbone provides the extra bone space needed for anchoring the enormous breast muscle.
Having extra power helps but getting something as heavy as a turkey into the air requires additional adaptations. While eating your turkey this Thanksgiving, break open a bone or two. You will discover the bones are hollow, which reduces bird weight significantly. Birds drop even more weight by eliminating bones normally found in similar-sized animals, such as tail bones and most finger bones.
Then there is the beloved wishbone. Humans might think wishbones are magical devices that bring luck, but turkeys know better. As a bird flaps its wings down, the wishbone pinches together to store up energy, which gets released during the upstroke. By so doing, wishbones save energy and help to move air through a bird’s respiratory system.
Clearly animal physiology is much more interesting than whether you or your brother get the lucky end of the wishbone. Another fun fact is that wishbones are shared by the two-legged dinosaur relatives of birds, such as Tyrannosaurus rex.
We have only scratched the biological surface of your upcoming turkey dinner. You can learn more on your own about how air sacs allow birds to maximize oxygen intake, and how birds keep a low center of gravity by re-positioning the flight muscles used during the upstroke.
I close with one of my favorite quotes from middle school band. Whenever we misbehaved, which was perhaps more than once, our band director, Mr. Furniss, would bellow out, “Am I working with turkeys?” This Thanksgiving I answer, “Yes, Mr. Furniss, we are indeed working with turkeys. And the biology tastes so good.”
Dave Gammon is a professor of biology at Elon University in Elon.
