Who notices the fall of the sparrow? For starters, scientists in China, where the once-common sparrow is on the brink of extinction. Around the northeastern port of Tianjin, the sparrow population has declined by an estimated 90 percent since Mao’s days; in many parts of southern and central China, the birds have all but disappeared. The primary culprit is the nation’s extravagant use of pesticides, and the scientists believe the sparrows are just the canaries in the coal mine of China’s environmental health. But while pesticides will affect species all up and down the food chain, the sparrows have another problem: a two-legged predator. In China, sparrows are common cuisine, often served on the streets as crunchy kabobs.