Spring Migration

By Kathy Roome, Terry Griffin & Samantha Carouso

There are MILLIONS of birds flying over your head most nights this month! When you are outside enjoying a spring evening, look up. No, not at the stars. 

Look up and consider that during peak bird migration in May, there are hundreds of thousands of birds migrating over your head every single night. In fact, according to data from the Cornell Lab of Ornithology, over 8.9 million birds were flying simultaneously over the Adirondacks in the middle of the night on May 1, 2024. You couldn’t see them, but they were there alright, flying at about 55mph.

About 4,000 species of birds migrate every year all over the earth. Four billion birds migrate to and from the U.S. every  year.

How on Earth do they do it? Birds prepare by stuffing themselves silly before they leave on the trip. Take the Blackpoll Warbler. This bird doubles its body weight before taking off on a non-stop 2,300-mile, 86-hour journey, undoubtedly arriving at its destination looking quite trim and fit.

The highest altitude migrant ever recorded was Ruppel’s Griffon Vulture flying at 37,000 feet – seven miles above Earth! 

The long distance award goes to the Arctic Tern. These birds fly from the Arctic to the Antarctic and back again every single year, a round trip of nearly 50,000 miles. Over the course of their 30-year lifespans, that’s the equivalent of going to the moon and back three times.

We at the Grassland Bird Trust take a particular interest in grassland birds, naturally. (For info about the Trust, see the November 2024 issue.)  Bobolinks – the little birds who sound like R2-D2 – travel 12,500 miles round trip every year to Argentina, returning to the Washington County Grasslands Wildlife Management Area in Fort Edward each spring. One 10-year-old Bobolink that had been tagged apparently flew a distance equal to five times around the world. Pretty good for a bird that weighs only one or two ounces. 

Or consider the Short-eared Owl, another grassland bird. There are only about 50 pairs left who spend the entire year in New York State. The Short-eared Owls we see in Upstate New York fly north in spring to the Arctic and then fly back south for the winter, often returning to the exact same fields. They particularly like the Washington County Grasslands in Fort Edward. Apparently, the Washington County Grasslands are their idea of Florida.

How do birds find their way over thousands of miles back to a particular field? It remains a bit of a mystery. Only a few of them, such as water birds, learn from their families by traveling in flocks of multi-generational birds. The rest, according to A World on the Wing by Scott Weidensaul, are born with a genetic road map that tells them to fly in a certain direction, for a certain amount of time, at a certain time of year. 

How do they know which direction to go? Many migrating birds use the sun during the day to navigate and the stars at night. Scientists proved this by putting Bobolinks in a planetarium at the start of fall migration. The birds determinedly started hopping south. But then the scientists turned the stars around in the planetarium, and after a while, the birds started hopping north. (We wonder whether satellites will also confuse the poor birds!)

Another explanation of how birds migrate requires a rudimentary understanding of magnetic fields and quantum mechanics.

What about sleeping during migration? Apparently some birds are like college students on spring break. Their need for sleep decreases by as much as two-thirds. Other birds may be able to maintain flight while actually in a state of semi-sleep. As with many aspects of bird migration, we simply don’t know for sure.

Migrating is not for the faint of heart. Birds migrate mostly at night because there are fewer predators to worry about. On the other hand, up to one billion birds die during migration each year from colliding with windows. 

Birding is big business. One out of every three U.S. adults identify themselves as bird watchers. And U.S. birders spend about $279 billion per year.

But all of this is at risk. According to a March 2025 Report from Audubon and other conservation groups, bird populations are plummeting across the U.S. Grassland birds are disappearing the fastest. Grassland bird populations have declined about 43% since 1970 due to habitat loss. 

While it’s fantastic to consider the millions of birds passing over our heads this May, keep in mind that it could all be gone in a few decades if we don’t take action to protect these awe inspiring travelers. To learn more, go to: grasslandbirdtrust.org.