Many animals find birds to be easy food, especially medium- sized bird species like blackbirds. These animals may relax while keeping one eye open and avoid becoming prey.
These natives of the southern hemisphere can avoid predators by sleeping with one eye open, and it also guarantees that they never go without food.
Penguins often snooze while standing up and keeping one eye open. These animals benefit from unihemispheric slumber by shielding their young from vicious predators.
Marine animals frequently experience monohemispheric sleep. The bottlenose dolphin is able to get the necessary restorative sleep that it needs without drowning.
Despite being somewhat larger than blackbirds, these birds still need to be on the lookout for larger predators like the great horned owl and golden eagle.