Grouse and Pheasants
The Heath Hen
This subspecies of the Greater Prairie-Chicken was common in the northeastern states before 1800, including close to Boston and New York City, but went extinct in 1932.
The Heath Hen
This subspecies of the Greater Prairie-Chicken was common in the northeastern states before 1800, including close to Boston and New York City, but went extinct in 1932.
■ The largest muscles in a bird’s body are the breast muscles that power flight, which can account for 20 percent of a bird’s total weight. There are two separate muscles involved, one for the upstroke and one for the downstroke. In most species the downstroke muscle is about ten times larger. On our bodies the muscles for bringing our arms forward (downstroke) are on our chest, and the muscles for bringing our arms backward (upstroke) are on our back. Birds have evolved to have both muscles on the front, below the wings for better weight balance in flight. This sketch shows how the larger downstroke muscles (darker red) attach to the underside of the wing to pull it down, and the upstroke muscles (lighter red) wrap over the shoulder and attach to the top of the wing as a sort of pulley system. When you carve a chicken or turkey breast for dinner, you might notice the separation of these two large muscles.
Ring-necked Pheasant with breast muscles highlighted
■ Birds have many adaptations that make flight possible, and weight balance is one of the most important. The heavier bone and muscle of a bird is almost all in a compact central mass that rides below the wings. Wings and legs are controlled by long tendons connected to muscles in the compact body. The neck and head are very light, with a lightweight bill instead of heavy jaws and teeth. Try making a paper airplane, then tape a coin to different parts of the plane. It will only fly properly if the extra weight is below the wings and near the center.
Ring-necked Pheasant with actual flesh and bones shown in red; the wings and tail are mostly feathers
■ What’s the most common bird in North America? That would be the domestic chicken. The population at any given time numbers something over 2 billion birds—about 500 million egg-layers and the rest being raised for meat. That’s about five times more than the human population of the continent. In contrast, the best guess for the most numerous wild bird in North America is the American Robin, at an estimated 300 million birds. That’s about one-seventh of the chicken population, and slightly smaller than the human population.
Domestic chickens