Cave-dwelling oilbirds are the loudest-known and their calls can be deafening when they are in a flock. Oilbirds use echolocation like bats to fly around the pitch-dark caves but their calls are audible to people unlike bats. An oilbird’s squawking and clicking can be around 100dB, pretty painful to human ears.
Oilbirds emit short bursts of clicking noises, which bounce off of objects in the animals’ paths, creating echoes. The echoes return to the birds’ ears at different levels of loudness and intensity. The larger the object, the more sound waves that are deflected, making the echoes louder. This enables the birds to identify the size, shape, and location of the animal or object. What sounds like a single click to the human ear is in actuality an entire ‘burst’ of sonar signals. The oilbirds can thus receive constant spatial information from their surroundings, and can process this information much like the visual and audio sensations humans gather with our eyes and ears. This enables the birds to navigate at night without colliding into obstacles.
Picture Credit : Google