It's truly fascinating to think about how differently animals experience the world. Take birds, for example. Imagine having ears so incredibly sensitive that you could hear and pinpoint the exact location of a tiny mouse moving around in complete darkness! That's the kind of auditory superpower that barn owls have. As Director of Zoology and Health Sciences at the Denver Museum of Nature & Science, I've been part of a research team led by Dr. John Peacock, a research associate at the Museum, that's been digging into the many amazing aspects of bird ears. Our work is not only important for what we're discovering, but also visually stunning. I'm very proud that three of our studies have been honored with cover images in scientific journals. That's a pretty rare achievement!
Our research explores the complex world of bird hearing. We're particularly interested in the columella, which is a tiny but essential bone in the bird's middle ear. Think of the middle ear as a little sound amplifier; it takes sound vibrations from the eardrum and boosts them so they can be sent to the inner ear. My colleagues and I are working to figure out how the columella, that little bone, helps birds hear in so many different ways.
In one study, our team took a close look at the columellae of 401 different bird species. That's a lot of ears! We wanted to get a good overview of all the different shapes and sizes they come in. We found a huge variety, with some unique features showing up in certain bird groups. For instance, we saw a special columella structure in a major group of Accipitridae — think hawks, eagles and kites. We also noticed that some birds that spend a lot of time in the water have smaller "footplates," the part of the bone that connects to the inner ear, compared to the length of their columella. This kind of detailed comparison helps us understand how different bird species are related and how their ear structures have evolved over millions of years.
More recently, our research team has been investigating the middle ear of the barn owl. These birds are famous for their amazing ability to hear. We used laser vibrometry and other precise techniques to map out how sound travels through their middle ear. Our results show that the barn owl's middle ear amplifies sound in a way that's similar to what we see in mammals. But we also discovered that the timing of sound transmission is different in barn owls; it's faster than in other birds. We think this special timing might be one of the things that gives barn owls their incredible ability to pinpoint exactly where a sound is coming from, which helps them hunt so well in the dark.
Overall, I believe that our research is really contributing to our understanding of how bird ears have evolved and how they function. This knowledge might also help us improve hearing aids and other devices for people with hearing loss. By studying the amazing complexity of bird ears, we can potentially find inspiration for better ways to help people hear. It's exciting to think that by combining detailed anatomical studies with precise measurements, we're slowly unraveling the secrets of how birds perceive their world through sound. And the fact that our work has been featured on three journal covers? Well, to me, that says we're definitely making "waves" in the field – sound waves, that is!
Dr. Garth Spellman is Director of Zoology and Health Sciences and Curator of Ornithology at the Denver Museum of Nature & Science.