In a new study, researchers reported that crested pigeons have a built-in alarm system that blows when they flatter their wings while flying. The crested pigeons (Ocyphaps lophotes) when in danger fill the air with creaking whistles while taking the flight. This means they communicate without using their beaks and by blowing the alarm through the flapping of their wings, they alert other pigeons about the danger. This discovery has astonished the researchers because it was known earlier that the crested pigeons emit whistling sounds while flying as a regular phenomenon. But the study revealed that these whistling sounds were nothing but alarms send by the crested pigeons to other pigeons regarding any potential threat or danger.
Study co-author Trevor Murray, a biologist at the Australian National University in Canberra, said that in animals nonvocal sounds are not uncommon and all animals sound as they move, even humans and that sound could be useful to those that hear it. But for the first time, they figured out that some birds like the crested pigeon used their whistling sound for communication. For the study, the researchers recorded pigeons with and without various flight feathers.
Along with that, they recorded the flight take-offs under normal conditions and under fake threat conditions, when the pigeon takes off at high speed. The recordings demonstrated the influence of speed on the sound and revealed that the fast exit of crested pigeons served as a warning signal to other bird. Actually, crested pigeons posses 10 primary flight feathers on each wing. The eighth one, which is third from the top of a bird’s extended wing, does not look like normal feather. It is smooth slender and has an odd shape.
In 2009, a study revealed that this specialized wing feather might be the reason behind the noisy take offs made by the crested pigeons when they sense danger. So, recently the researchers tried to know the exact reason behind those whistling flights. For the research, Murray and his colleagues used high-speed video, audio recordings and feather-removal tests to have a closer look at this special feather and how it might produce sound. They found out that when the air flows across the feather’s pointed tip as the bird pushes down with its wing, the feather flutters and generates a high-frequency tone. Also, they found out that the feather below it amplifies this high-frequency tone and the feather above it helps in making a low tone during the flapping of wing. Hence, a creaking whistling sound is heard during the sudden takeoff. Surely it’s a great strategy to avoid danger both for the crested pigeons as well as other pigeons.