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A bird's digestive tract differs from our human digestive system because there are some additional features. First of all there is a cavity inside the beak containing the tongue which plays an important part in eating. The next part of a bird's digestive tract is the esophagus. It isn't just a tube-like structure. There is also a bag-like expanded portion, the so-called crop. This part of the body plays an important role: On the one hand, the seeds and grains are dampened there, it's a kind of preparation for the digestion in other parts of a bird's body. So inside the crop, grains and seeds are mixed with water and body secretions. And on the other hand, the crop is essential for storing the food adult birds need for feeding their chicks.

After remaining inside the crop for a while, the food passes to the stomach. Apart from humans, birds have more than one stomach: First, the food finds its way into the proventriculus, which is the glandular portion of the stomach. It secretes gastric juices like for example hydrochloric acid and pepsin which break down the food. After that, the mashed food passes to the ventriculus (or gizzard) where the food is pounded and the task of this part of the digestive tract is to grind up the food even more.

Tiny stones (gravel), grit and sand are needed for this mechanical work the second section of a seed-eating bird's stomach has to do. For this reason it is highly important to offer grit and sand to your birds in case you feed them on grains and seeds. Otherwise birds can become sick from the lack of those tiny particles their digestive tract needs. If you heard that gravel and sand are dangerous because some birds tend to eat too much of it, just keep in mind that they do so because they use it as a natural remedy when they feel sick. A bird owner always should have a close eye on the eating habits of his birds to prevent such a situation. In case a bird seems to eat too much sand or grit, you should take your feathered friend to an avian vet who will find out what is wrong with your bird's digestive tract. And please note that birds who eat pellets or extrudates do not necessarily need grit and gravel.

Now let's continue our virtual tour through a bird's digestive tract. Next, the food passes on to the small intestine where it is mixed with enzymes from the pancreas that play an important role in digesting starch, proteins and fat. Bile that origins from the liver breaks down larger sugar molecules.

The intestine of a bird is quite short. This guarantees a short retention period of the food within the digestive tract. After the food is completely digested and has passed the whole intestine, it is passed through the single opening in the urogenital system of birds which is located at the cloaca or vent. The cloaca itself is a small cavity that is connected with the intestine, the ureter and the crotches. Therefore faeces, urine, sperm respectively eggs leave a bird's body through the cloacal opening.

By the way: Biologists claim that evolution made two stomachs appear in birds because this means less weight for them. Those highly specialized stomachs do their work efficiently, so the food is quickly digested. It is important for birds that their food gives them energy as fast as possible and won't weight them down for too long because extra weight means more efforts while the animals fly.

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