Emus are very large Australian birds that cannot fly. In fact, they are the second tallest bird species that is alive today! They are ratites, which is a grouping of many flightless birds that includes the ostrich, emu, cassowary and rhea, among others. They are mostly grey-brown with very fine shaggy feathers, which insulate the bird from sunlight. Emus make a distinctive deep clicking sound which they make by inflating their neck sacs. These sounds can be heard 2km (1.24 miles) away! Impressively, they can also run at speeds of 50km/h (30 mph). They are also great distance travelers. They spend most of their time with other emus, and are very social. Staying in groups means they are more likely to spot predators.