Colonies of two-foot-tall African penguins gather along the continent’s southwestern coast and islands, at times forming a seemingly endless sea of what appear to be nearly identical individuals. Researchers who study the birds rely on the smattering of spots across each bird’s white chests to tell them apart—but they’re not the only ones. The penguins themselves use these dots, too, to identify their lifelong mates, according to a recent study in Animal Behavior. “Especially in birds, people focus on recognition through vocalization most of the time, but sometimes we underestimate…
