Around the world, invasive animal species are pushing out the natives, sometimes forever altering ecosystems. House sparrows are a prime example, having spread from Europe to most inhabited parts of the world. By following the house sparrow invasion of Kenya, researchers have gleaned key traits underlying its incredible success. They documented differences in the immune system and stress responses in birds on the leading edge of the expansion. And last month, they reported finding another clue: a penchant for novel foods in those beachhead birds. The discovery adds to the growing body of evidence about the benefits of behavioral flexibility for animals moving outside their natural homes.