Ornithology Exam II – Anatomy & Physiology Practice Test

Color vision depends on the number and types of cone photoreceptors in the retina, each tuned to different parts of the light spectrum. Birds have four distinct cone types, including a sensitivity to ultraviolet, which gives them tetrachromatic vision with four separate color channels. In contrast, mammals typically have three cone types corresponding to short, middle, and long wavelengths, providing trichromatic vision. Some mammals can be dichromats, but the common pattern across many species is three cone types rather than four. Reptiles and fish more often have four or more cone types, giving them additional color channels beyond three. So, mammals are the group that typically has three cone types instead of four.