Years ago, a respected ornithologist told me what I thought was a preposterous tale: Untold numbers of migrating ruby-throated hummingbirds, he said, fly nonstop 600 miles across the Gulf of Mexico each spring and fall to reach their destinations.

In the spring, he said, the tiny birds fly from their winter homes in Mexico’s Yucatan peninsula and in Central America to summer nesting grounds in North America. In the fall, they make the reverse trek back across the Gulf.

I was incredulous. It was mind-blowing to think that a tiny bird weighing no more than a nickel could fly 18 hours straight across the Gulf of Mexico without ever resting or refueling.

I wasn’t the only skeptic. Many ornithologists at the time believed that hummingbirds burned so much fuel flapping their wings that they simply could not survive a nonstop trip across the Gulf. The birds were thought to fly over land across Mexico, making refueling stops along the way.

An alternative theory was that the little birds flew across the Gulf on the backs of ducks and geese, but most ornithologists dismissed that notion as ridiculous.

Today, from radar studies and other research, we know the truth: Untold numbers of ruby-throated hummingbirds do indeed fly nonstop more than 600 miles across the Gulf of Mexico during their spring and fall migrations. Giff Beaton, one of Georgia’s top birders, says the feat sounds as astounding to him today as when he first heard about it years ago.

The hummingbirds already are arriving in Georgia for their nesting season. Jaynne Reichart in Bryan County in South Georgia said two male hummers showed up in her yard this week. “My husband made new hummingbird (nectar) and put our five feeders out,” she said.

Ruby-throats, of course, are not the only birds that make incredible nonstop journeys across the Gulf. Millions of migrating songbirds do so as well. They, too, will begin arriving for their nesting seasons within the next few weeks.

IN THE SKY: From David Dundee, Tellus Science Museum astronomer: The moon will be first-quarter today. Venus and Mercury are low in the west at dusk. Jupiter rises out of the east just before midnight. Mars and Saturn rise out of the east about an hour after midnight.