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Owls hold secret to ageless ears

Off the track

Owls hold secret to ageless ears

Barn owls keep their acute sense of hearing into old age, scientists have discovered. Previously, starlings have been found to have this ability, suggesting birds are protected from age-related hearing loss. Understanding more about the “ageless ears” of barn owls could help develop new treatments for human hearing problems. Birds are able to naturally repair damage to the inner ear. Georg Klump of the University of Oldenburg, Germany, a researcher on the study, said owls keep their hearing into very old age. “Birds can repair their ears like (humans) can repair a wound,” he said. “Humans cannot re-grow the sensory cells of the ears but birds can do this.” It appears that humans lost these regenerative abilities at some point in evolution. Like all mammals, people commonly suffer from hearing loss in old age. By the age of 65, humans can expect to lose more than 30 dB in sensitivity at high frequencies. Commenting on the study, Dr Stefan Heller of Stanford University School of Medicine, said work was underway to investigate differences between birds and mammals. “To truly utilise this knowledge, we need to conduct comparative studies of birds and mammals that aim to find the differences in regenerative capacity, a topic that is actively pursued by a number of laboratories worldwide,” he said. The research, published in the journal, Royal Society Proceedings B, was carried out on seven captive barn owls. The birds were trained to fly to a perch to receive a food reward in response to sounds. Even the oldest owl, which reached the ripe old age of 23, showed no signs of age-related hearing loss. Barn owls typically only live to the age of three or four in the wild. The birds rely on their hearing to hunt prey at night. Because owls are generally active at night, they have a highly developed auditory (hearing) system. The ears are located at the sides of the head, behind the eyes, and are covered by the feathers of the facial disc. The “Ear Tufts” visible on some species are not ears at all, but simply display feathers. The shape of the ear opening (known as the aperture) depends on the species of owl - in some species, the opening has a valve, called an operculum covering it . The opening varies from a small, round aperture to an oblong slit with a large operculum. All owls of the family Tytonidae have rounded openings with large opercula, while in Strigidae, the shape of the outer ear is more varied. An owl’s range of audible sounds is not unlike that of humans, but an owl’s hearing is much more acute at certain frequencies enabling it to hear even the slightest movement of their prey in leaves or undergrowth.

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