Birds' UV Vision Reveals Colors Beyond Human Perception

Birds possess a visual system that surpasses human capabilities. Their eyes are proportionally larger, with a higher density of photoreceptor cells and four types of cone cells, enabling tetrachromacy and the detection of ultraviolet (UV) light that humans cannot see. Structures such as the pecten—a comb‑like retinal feature unique to birds—support retinal nutrition and may aid motion detection, while a more flexible lens allows rapid accommodation.

By contrast, human vision relies on three cone types and is limited to the visible spectrum. This difference has led some to speculate that the vivid colors described in near‑death experiences could correspond to the UV spectrum perceived by birds, offering a scientific analogy for “heavenly” hues.