When a robin is searching for worms in the ground, it turns its head and leans downward. Because of this position, most people believe that the bird is straining to “hear” the worm.
But birds have their eyes on the sides of their head, and therefore must turn their head to the side to see what’s in front of them. So when a robin turns its head while searching for a worm, the question arises, is it trying to see the worm or hear it?
Scientists conducting experiments with birds have found that blind birds still turn their head toward the ground when they’re hunting for worms and that blindfolded owls can still catch mice.
So it’s probably true that a bird’s sense of hearing is sharp enough to pick up the faint sound of a worm moving through its burrow.
Seems after doing some online research I concluded that no one has properly discerned the robins method of identifying a worm, and I certainly beg to differ that a robin uses sight as primary sense to locate worm, because I have observed them digging into submerged soil and grass to pull out worms on many occasions, dolphins use sonar to find hidden fish in the sand in the Caribbean, additionally I have noticed that noisy conditions like a lawn mower does not hamper the robins worm detecting sense, maybe if we spent less time looking for life on Mars and spend more time on our glorious planet we would know the answer,