Birds have 'ageless ears,' but airport noise may push them

Q: I work at the airport and see many birds. Because of all the noise around here, I'm wondering if they become deaf.

A: That's a fascinating question, and one I hadn't encountered before. After doing a bit of research, I learned that birds have the ability to regenerate the cells involved in hearing. Scientists call this "ageless ears," because as birds age they regrow tiny hair cells in the cochlea, the structure that relays sound waves. Older birds hear as well as young ones. Mammals lack this ability and it may have implications for improving human hearing aids.

However, this proficiency is not without limits, as researchers working to develop acoustic deterrents to birds invading crop fields and airports have discovered. Repeated exposure to loud sounds can overwhelm birds' ability to regenerate their hearing. So I'd say that yes, birds that spend a great deal of time around runways are probably suffering from hearing loss.

Q: What are wild turkeys doing in St. Paul? We see them near busy intersections all over the western side of the city. Aren't they in danger of being hit by cars, and where do they come from?

A: More and more of us are seeing wild turkeys in the urban landscape, in backyards, parking lots, roadways and just about everywhere else. The birds have discovered that cities and suburbs are rife with turkey food, such as acorns, other nuts, and seeds dropped from bird feeders. I suspect that the flocks you're seeing came up from the Mississippi River bottoms. They can fly, but not for long distances, and at night they launch into a tree's low branches, then hop upward to spend the night. And yes, vehicles pose a grave danger to wild turkeys in the road.

Q: The birds drop seeds from the feeder and they sprout on the ground. Is there any way around this?

A: A surefire way to avoid sprouting seed is to offer seeds that have been shelled, since these have been treated with heat to stop germination. Sunflower seed hearts are a good choice, or consider other-than-seed foods, such as peanuts and suet.

Q: I know this isn't a bird question, but I can't find any information about whether bats hibernate or migrate.

A: The short answer is that they do both. Minnesota has seven bat species, three of which migrate in the fall. The other four bat species seek out a cave (or cool attic) for their winter hibernation.

Q: People look at me like I'm crazy when I talk about this, but I've observed Canada geese engaging in what I call migration instruction for the new guys. Usually a group of geese is divided into lines by a drill sergeant barking orders, and then a line will take off. Have you seen this behavior?

A: Your theory about Canada geese preparing for migration is a fun one to think about, but I haven't read anything about it. It's generally agreed that geese remain together as family groups and fly together within flocks. When geese forage in the open, one member of the flock will serve as a sentinel, allowing the others to feed while making sure no predators are sneaking up on them. This sentry bird often makes soft sounds, perhaps to reassure the flock that the coast is clear. I'd suspect that most learning about migration occurs in the air, a sort of on-the-job training as adults lead youngsters to their winter home.

Q: Can you identify the bird in the photo? It hit my window and perished, but with all the windows I have in this house, one death maybe isn't a bad record.

A: It can be a challenge to identify dead birds, but the one in the photo you sent looks like a Nashville warbler. I'd like to ask you to reconsider your feeling that one bird death is acceptable. I'm a relentless proselytizer about the need to make our home windows more apparent to birds, so they don't crash into them and get injured or killed. For very little expense and effort, you can put decals on any window that a bird has hit, to make it more apparent to birds. A brand I use is WindowAlert: You can find these online or in wild bird supply stores. The decals are almost invisible to the human eye but reflect UV light, which birds can see. You don't need to retrofit all your windows, just the ones that birds have run into.

St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net