The duck breasts and whole ducks sold in supermarkets are usually Pekin, or Long Island, ducks. Once raised on Long Island, these birds are now grown on farms around the country, and the largest producer is in Indiana, a long way from New York. Most duck breasts are sold whole, with the skin on but without the bones. They can be split nicely into two halves, each weighing about 6 ounces.
Other duck species are available if you are willing to order by mail or can shop at a specialty butcher. The Muscovy is a South American bird that is less fatty than the Pekin and has a stronger game flavor. The Moulard is the sterile offspring of a Muscovy and a Pekin duck and is popular in France. Because these birds are so much leaner, the breasts require a different cooking method. Since the Pekin duck is the breed found in supermarkets, we decided to stick with this variety when developing our recipe for Grilled Duck Breasts.