© H. Schmidbauer/Offse
As their name suggests, these tiny, round-bodied birds are distinguished by their long, narrow tails. In fact, the tails account for most of their body length—just over 5 inches, body, tail, and all. They’re gregarious creatures, forming flocks that range from just a few birds to as many as 30. Their nests are small flexible sacks with round holes on top, and are made of lichen, feathers, moss, and spider egg cocoons. They hunt caterpillars and other insects, and are found across the temperate climate zones of Europe and Asia.