Spring songbird migration is well underway, with sparrows – song, white-throated, fox, chipping, towhee and junco – all over campus this morning. There were a few other songbirds – a wren, and golden-crowned kinglets – as well, and likely some other sparrow species I could not identify in the distance and dim morning light.

 

Why Do Birds Migrate?

Yes, it’s because of the cold, but not for the reason most people think. Birds feathers are mighty fine insulation, and we know that birds can survive Michigan winters because we still have quite a few around. It’s more a matter of food availability. If a bird’s major food source is insects, then Michigan is not a great place to be in the winter unless you’re a woodpecker (or a very industrious chickadee!)

The Hazards of Migration

Migration is perilous. Bad weather, predators, lack of food resources and many other dangers await. In cities, one of the biggest hazardous are building windows. Part of my morning ritual now is to patrol campus, looking for birds that have struck windows. Sometimes this is fatal, sometimes they get away with a concussion or just a slight jarring, depending on how hard and fast they hit the window.

I’m doing this in cooperation with Detroit Audubon and their Great Lakes Safe Passage program. Window strike data is recorded and uploaded. I am also collecting specimens in good condition for eventual preservation and addition to Wayne State or University of Michigan’s natural history museum collections. This data can help us to monitor migration patterns and areas of highest strike density so that we can make plans to mitigate the strikes. More on that in a future post.