400-year-old painting reveals a bat's secret diet

Natural historians have many observational techniques in their toolkit for learning about the natural world: tagging animals with tracking devices, recording sounds, analyzing droppings or simply watching and counting.

As technology has advanced, these methods have grown far more precise and wide-reaching, letting researchers capture details that were once impossible to detect.

Even today, however, these cutting-edge tools aren't the only route to discovery. ...