Which organ is considered the main part of a chicken's excretory system?

The kidneys are indeed a vital component of a chicken's excretory system as they play a crucial role in filtering waste from the bloodstream and regulating water and electrolyte balance. In chickens, the kidneys work to excrete waste products, primarily in the form of uric acid, which is less toxic and conserves water—an important adaptation for birds.

While other organs, like the liver, intestines, and cloaca, contribute to various bodily functions, they do not serve as the primary site for waste filtration and excretion in the same way that the kidneys do. The liver is involved in metabolism and detoxification, the intestines are central to digestion and nutrient absorption, and the cloaca serves as a common exit point for digestive, urinary, and reproductive tracts. However, the kidneys are specifically designed for the filtration of blood and the production of urine, making them the main organ involved in the excretory process for chickens.