These tropical hummingbirds make cricket-like sounds other birds can't hear

These tropical hummingbirds make cricket-like sounds other birds can't hear Researchers have found that a tropical species of hummingbird called a black jacobin makes vocal sounds with an unusually high-frequency pitch that falls outside birds' normal hearing range. It's not yet clear whether the hummingbirds can even hear themselves, the researchers say. http://ift.tt/eA8V8J