The Tiny Life of a Hummingbird: A Heart That Races Past 1,000 Beats a Minute

If a ruby-throated hummingbird visits your yard this summer, there is a good chance she weighs less than the nickel in your pocket. A nickel is five grams. She is usually around three.

Everything about her life is built around that number. A body that small loses heat fast and burns fuel faster, and the way she lives, from how she flies to how she sleeps to how she migrates, is a solution to that problem.

A nest two inches across

Female ruby-throats raise their young alone. She builds a nest about two inches across, woven from plant down and bound with spider silk, which lets it stretch as the chicks grow. She covers the outside with bits of lichen so it looks like a knot on the branch.

Inside, she usually lays two eggs, each about the size of a jelly bean. The chicks hatch after roughly two weeks, and she feeds them on insects and nectar until they leave the nest about three weeks later.

Built to hover

In normal flight, her wings beat about fifty times a second. That is fast enough to blur into a hum, which is where the name comes from. Hummingbirds can rotate their wings in a figure-eight at the shoulder, so they get lift on the backstroke as well as the downstroke. That is what lets them hover in place at a flower, and even fly backwards, something almost no other birds can do.

All of that burns energy. In flight, a hummingbird's heart can race past a thousand beats a minute, and she needs to feed every few minutes through the day, visiting hundreds of flowers and feeders.

How she survives the night

So what happens when she cannot eat? On cold nights, or when she is low on fuel, she can drop into torpor, a deep energy-saving state a bit like a short hibernation. Her body temperature falls, her breathing slows, and her heartbeat can drop to around fifty beats a minute. In the morning she warms back up and goes looking for breakfast.

Five hundred miles, nonstop

In late summer she starts eating more than ever. Before migrating, a ruby-throat can nearly double her body weight, storing the extra as fat. That fat is fuel for one of the most remarkable trips any bird makes.

Many ruby-throats fly straight across the Gulf of Mexico, about five hundred miles of open water, without stopping. There is nowhere to land and nothing to eat along the way. Others take the longer route around the Gulf over land. Either way, they winter in Mexico and Central America.

Then, in spring, many of them come back to the same area they left, sometimes the same backyard and the same feeder. Bird banders have caught the same individual birds at the same spots year after year. And there, she builds another tiny nest, about two inches across.

Watch the Short

Frequently Asked Questions

How much does a ruby-throated hummingbird weigh?

About 3 grams, less than a U.S. nickel, which weighs 5 grams.

Do hummingbirds really fly across the Gulf of Mexico?

Many ruby-throats do, flying about 500 miles of open water without stopping. Others take the longer route over land around the Gulf.

What is hummingbird torpor?

A deep, energy-saving state hummingbirds enter on cold nights. Their body temperature drops and their heart rate slows sharply until morning.

Related Stories

• The Life of an Ant
• Three Hearts and Blue Blood: The Giant Pacific Octopus
• Alex the Parrot

Bring Them Closer

Get one true animal story in your inbox each week. Sign up at the bottom of this page.

Sources

• Cornell Lab of Ornithology: Ruby-throated Hummingbird life history, nest size and materials, clutch size, egg size, and nesting timeline.
• Audubon Field Guide: Ruby-throated Hummingbird, range, migration, and feeding behavior.
• Ruby-throated hummingbird, weight, wingbeat rate, torpor, pre-migration weight gain, and the nonstop Gulf crossing.
• National Geographic: Hummingbirds, heart rate, metabolism, hovering, and backward flight.
• Cornell Lab of Ornithology: Ruby-throated Hummingbird overview, identification of females, which lack the male's red throat.

Photo: female ruby-throated hummingbird via Wikimedia Commons (CC BY 2.0).

More animal stories: From Paw to Tail Blog