From ancient times to the present, the flying crane Xiangyun is a sign of auspiciousness, and photography enthusiasts capture the real "Xiangyun", which makes people have to sigh that art really comes from life, and the ancients are too realistic. Birds, on the other hand, defecate anytime, anywhere, but they can really enhance their ability to fly.
With the exception of ostriches, birds do not have bladders, and urine and feces are carried out at the same time, and are excreted through the cloaca. Birds have a rapid metabolism, a short rectum, and are able to absorb food nutrients quickly, and useless residues are quickly excreted. In order to keep the body light, birds will immediately discharge excrement when there is excrement, including when flying.
Birds' special body structure in terms of digestion, excretion, bone, etc., is to reduce weight in order to better overcome the earth's gravity to spread its wings and long sky.
