Nature's Helicopters

By Andrew Forbes | May 2, 2008
From Missouri Conservationist: May 2008

Early spring is one of my favorite times of the year. The weather is warmer after what seems like a lifetime of cold, gray days, choruses of spring peepers fill the night with sound, and the first spring wildflowers add a touch of color to the landscape. Adding to my enjoyment is the knowledge that my backyard will soon be host to a handful of ruby-throated hummingbirds. These energetic, noisy little birds entertain wildlife enthusiasts across Missouri.

There are 335 species of hummingbirds in the world—all of them in North or South America. Hummingbirds come in a variety of sizes, colors and shapes. The bee hummingbird of Cuba is the smallest bird in the world. It measures about 2.25 inches long from bill tip to tail tip and weighs less than a penny.

The giant hummingbird of South America is the largest hummingbird species. It measures about 8.5 inches long and weighs about three-quarters of an ounce—roughly the size of a large sparrow. The red-billed streamertail of Jamaica has decorative tail feathers that are 6- to 7-inches long by themselves, and the sword-billed hummingbird found in the Andes Mountains of South America is the only bird species known to have a bill that is longer than its body.

Ruby-throated hummingbirds are the only species of hummingbird regularly found in Missouri. They are about 3.75 inches long and weigh about one-tenth of an ounce. Both sexes are bright, golden-green on the back and crown and whitish underneath. Adult males have a shiny, ruby-colored patch of feathers on their throat, while females do not. Young males are similar to females in appearance.

While they are often spotted around flowering plants or hummingbird feeders during migration, ruby-throated hummingbirds prefer areas in or near woodlands or forests during the breeding season. The females build a walnut-sized nest out of plant down, lichens and bud scales, all held together by spider webs. Usually, the nest is located near water. The female, on average, lays two peanut-sized eggs and takes care of all the incubation, as well as the care of the young. The young hummingbirds fledge about 18 days or so after hatching.

As you’d expect, their high activity level and unique flight means that hummingbirds require a lot of energy. In order to deliver oxygen to hardworking muscles, their hearts have to beat fast. A rate of 1,260 beats a minute was recorded in one species of hummingbird.

To fuel their energy requirements, hummingbirds have to consume about half their body weight in food every day. Nectar from flowers and artificial feeders makes up a large portion of their diet, but hummingbirds also consume large numbers of soft-bodied insects and other arthropods, including mosquitoes, gnats and spiders.

I get a couple of phone calls each year from people who report hummingbirds that appear to be drinking from fruit on trees. Actually, they are probably feeding on fruit flies attracted to the fruit. In fact, they will often defend territories around trees that prove to be an insect smorgasbord.

Masters of Flight

When European explorers first saw hummingbirds, they guessed they were a cross between an insect and a bird. Indeed, no other birds are capable of the backward and forward hovering that hummingbirds have mastered. How do they do it? The answer lies largely in their specialized flight muscles and wing structure.

Hummingbirds have extremely large chest muscles in proportion to the rest of their bodies. The supracoracoideus muscle, responsible for the upstroke in bird flight, makes up about 11.5 percent of a hummingbird’s total weight. Proportionally, that’s about five times more than in other birds. Also, the chest muscles in hummingbirds are composed purely of red muscle fibers (“dark meat”), which enable long, sustained periods of muscle activity.

The feathers on the wings of hummingbirds are also very different from other birds. The flight feathers closest to their body, called secondaries, are small, while the outer flight feathers, called primaries, are proportionally much longer than normal. This enables each wing to act somewhat like a propeller.

Unlike the mostly vertical flapping motion used by most other birds, hummingbirds beat their wings on a horizontal plane, similar to a helicopter. Their wings move backward and forward at a blinding speed, averaging around 50–70 beats per second! The tips of their wings make a figure-8 motion on each stroke. This creates just the right amount of lift to hover in place. To move forward, backward or any other direction, they change the angle of their wing stroke, creating thrust in whatever direction they want to go.

Incredible Journey

Most amazing about ruby-throated hummingbirds is their annual migration. What we think of as “our” hummingbirds actually spend about eight months of the year either migrating or spending the winter in Mexico or Central America.

In late July or early August, hummingbirds begin migrating south. The males leave first. You will likely see the most hummingbirds in Missouri in late August to early September as they work their way south. By early October, most hummingbirds are gone.

Fall migration coincides with the blooming of late summer flowers, especially jewelweed (Impatiens sp.). Hummingbirds are especially hungry this time of year because of the energy demands of migration. Artificial feeders are undoubtedly a lifesaver for many birds.

Once they reach the Gulf Coast, they fatten up, increasing their body weight by 50 percent. When they decide to leave, they fly straight up, sometimes ascending so high that they can’t be seen. Many fly directly south across the Gulf of Mexico, while some fly along the coast. Their 500-mile, non-stop flight usually takes them about 20 hours or so from start to finish, depending on weather. The journey takes its toll. Some don’t make it, and those that do might lose about half their weight.

They continue the rest of their trip along land, eventually settling in the tropics, where they feast on the abundant food. A few months later, they’ll head back north. The first males usually arrive back in Missouri in early April, followed about a week later by the females.

The next time you see a ruby-throated hummingbird, think about everything that bird has gone through to survive. It’s a good thing they have oversized determination and endurance.

To learn more about ruby-throated hummingbirds, explore the links listed below, where you can get information about dealing with hummingbird-related problems.

Hummingbird Banders

Much of what we know about hummingbirds—their migrations, life spans and survival rates—is based on data collected by a small but dedicated group of hummingbird banders. They capture birds, note their age, sex, weight and other information and fit the birds with tiny, uniquely numbered aluminum leg bands before releasing them.

This enables biologists to track birds over time and learn about their population trends and life history. Troy Gordon, a Missouri-based bander, has banded approximately 2,500 hummingbirds in central Missouri. He has captured two birds that were 8 years old. The oldest age ever recorded for a ruby-throated hummingbird is 9 years old.

Feeding Hummingbirds

Putting out hummingbird feeders is an inexpensive way to enjoy and help out hummingbirds. Many different styles of feeders are available. Most anything with red on the base will work. You can make the “nectar” on your own by mixing one part granulated sugar (don’t use honey or any other sweetener) with four to five parts water, and boiling it. Adding red food coloring is not necessary. Promptly refrigerate any unused portion.

Hang your feeder in a somewhat shady spot and fill it with enough sugar water to last a couple of days. Change the water every few days, and be sure to rinse the feeder with warm water. Soak the feeder for an hour or so every month in one-quarter cup of bleach to 1 gallon of water solution to kill any hidden mold. Don’t use soap; hummingbirds don’t like the taste of it. Rinse thoroughly after soaking.

You can keep your feeder up as long as you like. Making food available won’t interfere with migration, and you may even help out a few stragglers. Mid-March through October is a good time frame to start with. Pay special attention to any hummingbird that you see after mid-October. It could be a rufous hummingbird, a rare western visitor that sometimes migrates through Missouri.

You can also attract hummingbirds by planting flowers that they like. Some native species that are hummingbird magnets include trumpet creeper, cardinal flower, jewelweed and columbine.

Also In This Issue

Teens compete for the future of agriculture and conservation—and national honors.
Smallmouth bass in landing net
Tired of fighting the crowds of Missouri’s big-name smallmouth streams? Try a tributary.

This Issue's Staff

Editor In Chief - Ara Clark
Managing Editor - Nichole LeClair
Art Director - Cliff White
Writer/Editor - Tom Cwynar
Staff Writer - Bonnie Chasteen
Staff Writer - Jim Low
Photographer - Noppadol Paothong
Photographer - David Stonner
Designer - Stephanie Ruby
Artist - Dave Besenger
Artist - Mark Raithel
Circulation - Laura Scheuler