For the Birds Radio Program: Baby Mice and Owls
Baby white mice are very loud when nursing, and Laura made a recording of their sounds. She wonders if wild mice are that noisy in a world of owls and other predators. (This program was created before she was aware of research that establishes that Great Gray Owls are almost exclusively hunters of voles, not meadow mice, but the question remains.)
Transcript
Baby mice
Imagine being a hungry owl searching for mice on a snow-covered field. Virtually all the time, the mice are hidden deep inside their tunnels, under the snow. How can an owl find such well-hidden prey? Based on the white mice I have right now, I suspect hearing these mice may be easier than I thought.
I used to wonder just how noisy tiny mice could be, until I had a few white mice of my own. The female had babies a couple of weeks ago now, and I can actually hear the babies nursing when they’re in a different room. Naturally, that prompted me to pull out my microphone and record them, and that’s the sound you’re hearing in the background. It would be an easy matter for a Great Gray Owl with its huge, sound collecting facial disks, to pick up anything that noisy!
Of course, these are domesticated white mice, which belong to the species Mus musculus. They’re in a different genus than the mice typically caught in northern bogs. Great Grays are far more likely to hunt for White-footed and Deer Mice belonging to the genus Peromyscus, and voles belonging to the genus Microtus. I don’t know what those babies sound like, so may have to eventually try to raise some just to find out. But meanwhile, since house mice are no less vulnerable to predation than other mice, I think it’s a safe assumption that mice are noisier than we might have thought. I have a recording of them on my website in case you’ve ever had a hankering to do a web search for baby mouse sounds.
Because there have been so very many Great Gray Owls in Minnesota and northern Wisconsin this year, with some seen as far south as Madison, Wisconsin, there has been a lot of competition among them for food. Some have stuck to their mousy diet and seem to be faring okay. Virtually all of the ones treated at the Raptor Center in St. Paul this year have not been starving at all, but were brought there due to trauma—mostly after being hit by cars. But with so much competition in the best hunting areas, some Great Grays have retreated to more unusual habitats, with more unusual prey. I’ve been developing a database of sightings of them eating items other than mice and voles this winter, and have amassed quite a list of birds eating unusual prey. Many of them have been seen eating rabbits. Park Point residents seem pretty pleased with that, but some people who had bonded with a cottontail or snowshoe hare at their feeders were more unsettled by this. I’ve accounts of great grays also eating Red, Gray, and Flying Squirrels and a couple of unidentified grouse. One was killed when it crashed into a bay window—on the inside was a little dog sunning itself. There is one instance of a Great Gray eating a Northern Hawk Owl, and two tragic cases of them eating other Great Gray Owls. I’ve gotten one account of a Great Gray Owl feeding on venison suet at a feeder, and one of a Great Gray dropping from a feeder to take finches feeding on the ground beneath.
That’s the wonderful thing about studying birds—you can never possibly know everything about any species, and you never know what you’re going to learn next. If you have interesting stories about this year’s owls, send me an email at laura@binoculars.com