The enzymes that act inside the small intestine are amylase, protease, and lipase. Amylase acts on starch and breaks it down into small carbohydrate molecules. Protease acts on proteins and breaks them down into amino acids. Lipase breaks down dietary fats into smaller molecules called fatty acids and glycerol.
Sandhill Cranes mate for life, choosing their partners based on dancing displays. Displaying birds stretch their wings, pump their heads, bow, and leap into the air. Although each female usually lays two eggs, only one nestling typically survives to fledge.
Ducks are a collection of different species of bird. They are waterfowls, with feathers and feet specially adapted to life in and around water. Like all birds, ducks lay eggs, but that is only one phase of their life cycle. Hatching, maturing and mating are also steps ducks pass through during their life cycle. Mating Habits Unlike other waterfowl, such as swans and geese, ducks do not mate for life. Each seasonal bond is monogamous, but most species choose a new partner at the beginning of the mating season in winter. In addition, a much smaller number of duck species -- around seven percent -- practice polygamy.