November 13, 2015
By Michael Macek
Curator of Birds
Director of the WildCare Institute Center for Conservation in Punta San Juan, Peru, and of the Center for Conservation of the Horned Guan
At least 4,000 avian species regularly migrate each year—about 40 percent of the total number of birds in the world. I first became fascinated by this twice annual passage as a child growing up on the south side of Chicago. My ecosystem was mostly concrete with a few patches of green along the railroad tracks. But the skies above my house were filled with starlings, house sparrows, gulls and pigeons. They offered my first, and often only, exposure to wild animals.
Even decades later, I never tire of watching the graceful sweep of migrating birds as they make their way south in the V-shaped flocks. Some travel thousands of miles and reach great heights in this amazing passage.
You might ask why birds migrate. For the same reason people do. They are looking for resources—principally food and nesting locations. Birds that nest in the Northern Hemisphere tend to migrate northward in spring to take advantage of burgeoning insect populations, budding plants and lots of nesting locations. As winter approaches and available food disappears, these birds move south again. Escaping the cold is also a motivating factor for many species.
Some migrating birds are wired for traveling the same course year after year—somehow finding their winter home despite never having seen it before and returning the following spring to where they were born. The secrets of these amazing navigational skills aren't fully understood We think they get compass information from the sun, the stars and by sensing the earth's magnetic field.
All this may sound peaceful and poetic, but migration can be extremely dangerous for birds. Many don't make it back to their starting point. Sometimes natural occurrences like harsh weather play a role, but many times, human activities are the cause.
Thousands of migratory songbirds, which are attracted by lights, are killed each year by colliding with lighted buildings at night. In the United States alone, up to one billion birds die each year from these window collisions. You can help: At night, turn off the lights or close the blinds of your high-rise offices or apartment buildings, and spread the word to your co-workers and neighbors.
Habitat loss is another threat to birds. The number of bird species at risk of losing half their habitat by 2080 is over 300. It's estimated that in our own Mississippi flyway alone, loss of habitat could lead to a 19 to 39 percent decline in ducks by 2030. Climate change is the culprit. As climate warms, it's predicted that a significant rise in average sea level could eliminate up to 45 percent of our wetlands.
What can you do to help? You can work to save habitat by encouraging establishment of nature preserves and parks. You can put up bird houses (with proper ventilation). More than two dozen different bird species including the purple martin, house wren and eastern bluebird will nest in bird houses.
You can put bird baths out to provide a year-round clean drinking and bathing water source for birds. And erect bird feeders and nectar feeders in proper distances from windows or places where birds can't be ambushed by predators. House cats are one of the biggest threats birds face in the wild—cats kill somewhere between 1.3 and 4 billion birds every year in the U.S.
You can limit the use of lawn chemicals and pesticides in your garden—they are harmful not only to birds, but to a variety of wildlife.
When hiking, biking, going to the beach, or camping, you can stay on the trails and respect restricted sections of sensitive natural areas, especially during nesting season.
You can even purchase shade-grown "bird-friendly" coffee. Shade-grown coffee plantations support tremendously higher numbers of bird species than full sun (deforested) coffee plantations. Forested, shade-grown coffee plantations also benefit other wildlife and the people who live there.
And, if you are like me, you can all look up at the skies and marvel at the miracle occurring above you during these crisp autumn days. Together we can work to make sure the next generation will be able to see this beautiful sight.
Migrating birds photo credit: Farmers Almanac