Birds have the largest eyes relative to their size within the animal kingdom and eyesight is described as the most important sight for these feathered killers.
Nocturnal species have tubular eyes with low numbers of colour detectors, but a high density of rod cells which function well in poor light. Birds can resolve rapid movements better than humans, for whom flickering at a rate greater than 50 Hz appears as continuous movement. For example a Cooper's hawk can pursue agile prey through woodland and avoid branches and other objects at high speed; to humans such a chase would appear as a blur.