“Than Oars divide the Ocean,
Too silver for a seam—
Or Butterflies, off Banks of Noon
Leap, plashless as they swim.”
Despite our own disbelief that spring is just around the corner, all we have to do is look up now and again see that spring is truly on its way. The sight of migrating birds returning from their warm wintering grounds is something that’s seen every spring, but is truly never more welcome than when snow and 30 degree weather extends into mid-April.
Bird migration is one of the more amazing natural events that occurs twice annually, in both the fall and spring. This migration, or movement from one place to another, is due to birds’ search for the land with the most resources. Traveling anywhere from the bottom to the top of a mountain or between the northern and southern hemisphere, migratory birds move according to where their likelihood of survival and, even better, prosperity, will be the highest. Often taking extreme measures to find these resources, birds such as sand-hill cranes (which travel up and down the country), ruby-throated hummingbirds (many of which cross the Gulf of Mexico) and arctic terns (which fly from one pole to the other every year) all share the need to migrate.
While the reason for why birds migrate is relatively obvious, the question of how they know it is time to migrate is still unknown. Ornithologists believe that migration is possibly triggered by multiple factors including day length, temperature, changes in resource availability, and genetic predisposition (instinctual knowledge of exactly when to go). Just how birds get from one destination to another, usually the same destination every year and for generations, is also mysterious. It is speculated that they may use a combination of navigation via the stars, the earth’s magnetic field and smell to direct their route. If you are curious and want to know more about bird migration or birds that reside in the arboretum check out the Arb’s website or the Cornell Lab of Ornithology’s webpage (http://www.birds.cornell.edu/AllAboutBirds/studying/migration/).
If the weather is getting you down, take a moment to observe the ducks and geese swimming on an (ice-free!) Lyman Lakes or listen to the singing birds as you walk around campus or the Arb. They are a reminder that warmth and greenery will be here soon!