One-eyed pigeons still use sight to find

How homing pigeons find their way home has long mystified scientists. Experiments have shown they rely on smells to create a mental map of their route and on the sun or Earth’s magnetic fields to navigate. But they also use vision, memorizing roads, railway lines, and rivers. To understand just how important pigeons’ visual memories are for homing, scientists trained 12 birds to fly to their home lofts while wearing patches covering one eye (as in the photo above). Each bird wore a GPS logging device and made 18 flights with the left or right eye blocked, followed by another 18 trips with the opposite eye covered. Unlike mammals, birds lack a key neural structure—the corpus callosum—that allows both hemispheres of the brain to access what an animal sees. The experiments revealed that this missing neural structure affects the pigeons’ homing abilities, the scientists report in today’s the Proceedings of the Royal Society B. Pigeons that learned their way home with a blocked left eye couldn’t repeat the same journey when they wore a patch over their right eye, and vice versa. Instead, they flew slightly off course, following more of a curve than a straight line. The new work proves that vision, too, plays a key role in how pigeons find their way home.www.glorybios.com