A normal bird dropping has three separate components. However, since the bird passes a dropping out of one orifice, the vent, all three portions of the dropping are mixed in the cloaca before being evacuated from the body. The first portion is called the feces, which is solid and worm-like, and may be dark green in color (usually in seed-eaters), or brown (usually in pellet-consuming birds.) Feces may be other colors, as well, depending on what the bird has recently consumed. For example, certain berries will cause the feces to take on the color of the fruits ingested. It can be alarming if droppings suddenly appear reddish in color, as this may be interpreted as blood, so it is important that owners keep track of what their bird is consuming, so that color changes can be correctly evaluated. If a bird doesn't eat any solid food for about 24 hours, the fecal portion of the droppings will become dark, dark green (that is almost black) and very sticky and tarry. This is often mistaken for digested blood in the droppings, but it is actually a type of bile (biliverdin) from the liver.
If the feces portion is not formed, this is called diarrhea. Often, a dropping may have an increase in the urine portion, resulting in a very wet dropping, but the fecal portion will still be formed. This situation is often mistakenly called diarrhea, but it is not. If the feces portion is still solid, no matter how much urine there is in the dropping, then this is not diarrhea. Free water (urine) around the feces is evidence of increased urine in the dropping, not diarrhea. Be sure to check fresh droppings, as with time, the feces may absorb some urine, giving the false impression of diarrhea. If the brown or green solid fecal portion is not formed, or is very watery, then this is correctly called diarrhea. In some cases of diarrhea, there may be gas bubbles in the feces.
The next portion of the droppings is called the urates. Urates are off-white, cream colored or slightly yellowish, and are opaque. Urates are the result of digestion and metabolism of proteins in the bird's system. They are removed through the kidneys. Green or yellow stained urates may be found in the clinically ill avian patient with liver disease. Green urates can also be found in birds that are actively suffering from infection with Chlamydophila. If you notice a change in the color of a bird's urates, you should bring this to your avian vet's attention.
The third portion of a bird's dropping is the urine. This is the watery waste from the kidneys. There will be varying amounts of liquid urine in a dropping depending on the amount of water ingested. For example, a bird that is consuming a lot of fruits and vegetables (with high water content) will urinate more than a bird that is just eating dry pellets. Of course, a bird should always have access to fresh, clean drinking water, and it is best delivered by the use of a water bottle to prevent bacterial contamination from fecal matter and foods dunked in the water bowl.
http://www.exoticpetvet.net/avian/droppings.html
