Mallards sometimes sleep with one eye open
AI-generated cover illustration: крижень на краю зграї спить з одним відкритим оком, повернутим назовні від групи; ілюстративна сцена, не зображення експерименту. Походження: OpenAI image generation. Дата: 2026-10-20. Промпт: “Photorealistic vertical 4:5 wildlife editorial cover of a mallard sleeping at the edge of a small resting flock on a quiet pond at dawn. The outer duck is tucked into its feathers with one eye clearly open and facing away from the flock toward the open water, while ducks clustered inward rest with both eyes closed. Natural mallard plumage and anatomy, peaceful wetland, soft light. Illustrative scene of a known sleep behavior, not a photograph of the experiment and not a claim that the bird is fully awake. No text, no labels.”
When mallards sleep at the edge of a group, they are more likely to keep one eye open and directed away from the other birds, toward possible danger. During this kind of sleep, one brain hemisphere sleeps while the other remains more active. This helps them detect a threat, although it does not mean the duck is fully awake.