Note: This story is intended to be listened to. Text associated below is simply a transcript of the audio.
We have a hummingbird feeder. It’s one of those red plastic dishes you can hang by your window, or your porch. This winter in southern Arizona, it’s been particularly active. We’ve seen various kinds of hummingbirds coming to our front yard to feed in January, many of them species that would only typically show up later in the spring.
But winter isn’t hummingbirds’ time to be here. They usually come to Tucson to breed from March through September, after spending the colder months in Mexico and Central America.
They migrate alone, and they fly low, just above the treetops, so they can spot food along the way, traveling as much as 23 miles in one day. Scientists think they ordinarily migrate when they sense daylight changing, or if there are more flowers, nectar and insects available. This winter-humming at our feeder is due to climate change, of course.
“In the United States, a not-so-silent spring marks the arrival of several billion birds migrating northward from Central and South America. But curiously enough, the exact timing of this journey varies each year. So why is that?”
This is a video from NASA’s Global Modeling and Assimilation Office. Some of their research looks into the different climatic drivers surrounding U.S. bird migration.
The scientists analyzed 23 years of bird migration data to determine the variability in the birds’ arrival times each spring. And they identified two distinct regions — East and West.
In the East, bird migration was linked to large-scale atmospheric waves that affect the planet’s weather and climate.
“Variations in the West, however, seemed to be linked to more regional climate conditions, such as sea surface temperatures of adjacent waters.”
In other words, NASA data revealed that Western bird migration was more closely linked to air and sea surface temperature in the Pacific Ocean. In 2005, one of the West’s many recent above-average temperature years, migrating birds arrived to the U.S. earlier than average.
Future research hopes to build upon this to try to figure out how these trends are affecting specific migratory bird species.
I’ve always been fascinated by bird migration, by birds’ internal clock and that instinct, whether traveling solo or in a group, that brings them to warmer climates year after year after year.
As I watched the visiting hummingbirds through our living room window, I thought about a myth I once heard about hummingbird migration, before scientists understood the details. The tiny birds’ migration north, the myth said, was only possible because they rode on the backs of geese. What a fantastical thing that would be — if it could only be true.
This piece includes audio from NASA’s Global Modeling and Assimilation Office and from the BBC’s Sound Effects archive.
Encounters is a serial column exploring life and landscape during the climate crisis.
