Nest-building by birds is not an instinctive skill but rather something they learn and improve upon with experience, Scottish researchers say. Scientists from the University of Edinburgh filmed male Southern Masked Weaver birds in Botswana as they built several nests during a breeding season, a university release reported Monday. Nest-building techniques by individual birds varied from one nest to the next, the researchers said, and some birds built their nests from right to left while others constructed them from left to right. And their construction skills improved with each subsequent nest, as the birds dropped fewer blades of grass as they worked, suggesting nest building was a learning process. "If birds built their nests according to a genetic template, you would expect all birds to build their nests the same way each time," Patrick Walsh of Edinburgh's School of Biological Sciences said. "However this was not the case. Southern Masked Weaver birds displayed strong variations in their approach, revealing a clear role for experience. Even for birds, practice makes perfect."