Vail Daily column: Migratory birds travel through Colorado
Have you ever had the urge to court the great unknown — to sail or fly to lands you’ve only dreamed of? For many animal species, this is their reality. Migration, or the act of moving in order to escape changing seasons, or to find food or a mate, is still one of nature’s most alluring mysteries. Migration leaves us humans asking, how is it possible for the Arctic tern, a small sun-loving bird, to fly 22,000 miles nonstop from the North Pole to the South Pole and back again? How do red crabs, born just off the coast of the Indian Ocean and barely the size of your pinky fingernail, know how to return to their mothers in the hills — even though they’ve never been there before? Unfortunately, these questions do not have one simple answer, yet, thanks to the work of willful scientists, our curious nature can be contented.
Where Did The Birds Go
Now imagine the animal that epitomizes migration … if this animal is some kind of bird, then you are not alone in this thought. Long before the discovery of migration, people speculated about where birds “disappeared” to in the winter. For years, humans hypothesized that during the cold season, birds either transformed into completely different animals, burrowed into the dirt, or as Aristotle guessed, entered hibernation. However, can we really blame them? To this day, the thought that a bird as small as the broad-tailed hummingbird, beating its wings 100 times per second in order to travel northward or southward over the U.S., is still remarkable.
The Central Flyway
If you consider yourself a birder, or at the least are now intrigued, then the Eagle River Valley is a perfect place for you. The Central Flyway, one of four major migratory flyways in the U.S., goes directly through the state of Colorado. Because many birds take this pathway to and from their homes, you may get lucky now and again in seeing some of these beauties stop over in your backyard to take a rest from the grueling journey.
Guided by the Stars
This journey is not only physically taxing, but also cognitively tiring. Death is just around the wrong corner — birds must successfully navigate their way to a pinpointed home destination. If we use ourselves as the navigational standard, constantly relying on GPS, then birds are far superior. The earth’s sun, stars, magnetic field, and topographic features, such as the Rocky Mountains, are a few of the environmental cues that help birds navigate.
In fact, most of the showy songbirds that we have all come to love are flying thousands of miles in the dark. While it may seem precarious to take flight in the blackness of night, this adaptation proves beneficial. Birds are at risk of losing up to half of their bodyweight during migration, so in order to fuel up for the long ride, tiny songbirds must take advantage of the daylight for gorging on insects, nectar or seeds. In addition, traveling by the stars eliminates the threat of looming predators and heat exhaustion. One famous experiment, by Stephen Emlen of Cornell University, demonstrates how the stars are used as beacons. Inside of a planetarium, Emlen found that indigo buntings, vibrant blue songbirds, orient themselves to the area of stars that rotate the least. These celestial stars surround the North Star, Polaris, and remain consistent in their location. When Emlen rotated the position of Polaris in the planetarium sky, the buntings shifted their orientation as well. He found that lab-reared buntings could be pulled to other stars if he manipulated them to rotate the least. This means that night migrators are not necessarily “attracted” to the North Star, but inherently they respond to and learn from the stars that remain locked in position.
If we hope to catch a sight of these birds along their arduous journeys, then we must protect the integrity of riparian and prairie habitats that make up the Central Flyway. Let’s help keep these birds restless, so that future generations have the opportunity to be as curious about migration as we are.
Jenny Jochum is a naturalist at Walking Mountains Science Center in Avon.