Though the average Chinese consumes only a third as many eggs as the average American, and though most of those eggs are chicken eggs, China is renowned for its preserved duck eggs, including the “thou-sand-year-old” eggs. These and plain salt-preserved eggs come from the duck-rich southern provinces, where they made it possible to transport eggs to distant markets and store them for months during the off season. The proteins and membranes of chicken eggs are less suited to some of these treatments.