It's useful for both, actually. It's basically depth perception for both senses, since we've got 2 ears and eyes. At first, you're hearing/seeing from two points. Then when you tilt your head, you're rotating those two points on a different plane, giving you a different frame of reference.
Pretty sure they tilt their heads to get a better look at the thing they are looking at if I recall correctly
There might also be a thing with them tilting their head to find the direction of a sound
It's hearing, not sight.
Tilting their head means the sound hits each ear just a little bit off, and those milliseconds difference let's them locate the sound in 3d
It's useful for both, actually. It's basically depth perception for both senses, since we've got 2 ears and eyes. At first, you're hearing/seeing from two points. Then when you tilt your head, you're rotating those two points on a different plane, giving you a different frame of reference.
Nope, it's to hear how low to the ground something is by having sounds hit their ears at different times.