When a bird focuses both eyes on an object, it can estimate the distance, and…

Answer: increases its range of vision

Explanation:

When both eyes focus on the same object, the bird uses binocular vision to obtain depth cues and estimate distance. When each eye focuses on different objects, the bird uses each eye somewhat independently (monocular coverage), which expands the total area the bird can monitor.

• Binocular focus (both eyes on same object): improves depth perception and distance estimation.

• Separate focus (eyes on different objects): each eye covers different parts of the surroundings, increasing overall field of view and range of vision.

Why the other suggested answers are incorrect:

• The idea that the bird 'gets disoriented' is incorrect because separate focus simply broadens monitoring, not typically causing disorientation.

• Estimating the spectrum of colours relates to photoreceptor sensitivity and neural processing rather than whether the eyes focus on the same or different objects.

• The phrase about 'predicting virtual distance' is vague and does not describe the observed visual effect; depth prediction is tied to binocular focus, not to each eye focusing separately.