If you've ever hung a hummingbird feeder in the eastern United States, the little green bird zipping up to it is almost certainly a ruby-throated hummingbird. It's about three inches long and weighs around three grams. It looks like it could be blown away by a stiff breeze.
And yet some of these birds fly straight across the Gulf of Mexico. In spring, part of the population leaves Mexico's Yucatan Peninsula and flies roughly 500 miles over open water, landing first in places like Florida and Louisiana. The trip takes about 20 hours, with no food, no water, and nowhere to rest.
How Does Something So Small Make It?
On paper, the trip looks impossible. A nonstop flight that long seems to need far more energy than a three-gram bird could carry. Researchers found the answer: fat, and lots of it.
Before the crossing, these hummingbirds can double their fat mass. That fat is their fuel tank. During the long flight over water, they burn through the entire reserve, arriving on the other side running on empty.
Experience seems to matter too. Studies along the northern Gulf coast during fall migration found that older birds were better prepared for long flights than first-year birds, with higher body weights and bigger fuel loads.
A Body Built for Flying
Hummingbirds are flying machines. Muscle makes up 25 to 30 percent of their body weight. Their long, blade-like wings connect to the body only at the shoulder, which lets each wing rotate almost 180 degrees.
That unusual design lets them hover, fly forward, and even fly backward, moves that are more like an insect's than a bird's. When hovering, a hummingbird's wings can beat up to 80 times per second. That's where the famous humming sound comes from.
Their feet, on the other hand, are tiny. A ruby-throated hummingbird can only shuffle along a branch. When it wants to go somewhere, it flies.
Where They Go for the Winter
Ruby-throated hummingbirds breed across the eastern United States and southern Canada, especially Ontario. When the weather cools, they head south to spend the winter in Florida, southern Mexico, Central America as far as western Panama, and the West Indies. In winter, most of them are found in Mexico and Florida.
Not every bird takes the over-water shortcut, but the ones that do are making one of the most remarkable journeys in the bird world. Some birds also cross the Caribbean on their way north.
Small Bird, Big Survival Skills
Burning energy that fast has a downside. Hummingbirds need to eat often during the day. On cold nights, they can slip into a state called torpor, lowering their body temperature to save energy until morning.
They also face surprising enemies. Hawks, kestrels, and house cats will take them, but so will some unlikely hunters. Praying mantises have been seen ambushing adult hummingbirds at feeders more than once.
The oldest known banded ruby-throated hummingbird lived to 9 years and 1 month. Females tend to live longer than males, which rarely make it past 5, possibly because defending territory and then migrating take such a heavy toll.
So the next time one buzzes past your porch, give it a little respect. That tiny visitor may have crossed the Gulf of Mexico on nothing but a belly full of stored fat and a lot of determination.
