The Emydids are the largest, most diverse family of living turtles, with about 100 species in Europe, Africa, and the Americas. Their use of habitat is equally diverse. A few are terrestrial, living on land, such as box turtles and wood turtles. Most are aquatic, living in ponds, streams, or lakes. However, new scientific techniques have revealed that many aquatic Emydids spend a lot of time on land. Turtles are secretive and well-camouflaged, so it is tough to find them. Recently, scientists began gluing small signal-emitting devices (radiotransmitters) to turtles and then followed them for months or years using an antennae to detect the signals. While it was already known that aquatic turtles nest on land, radio-tracking revealed that they may also hibernate for the winter on land, travel over land to other bodies of water with better food supplies, or even just warm up while buried under leaves in a sunny spot.