2. Characteristics that are unique to birds are 1) feathers, 2) bills, and 3) a furcula (fused collarbone, or “wishbone”).
3. Approximately 2/3 of all the bird species are found in tropical rain forests.
4. To make them more lightweight, most birds do not have bladders to store urine. Rather than producing liquid urine to get rid of wastes, they produce a white, pasty substance.
5. Many birds consume 1/5 of their body weight in food every day to get the energy they need to fly.