Curious Nature: Learning more about the mighty, tiny hummingbird
June 30, 2012
Look up in the sky – It’s a bird! It’s a plane! It’s a … hummingbird!
Those fragile-looking little flecks of light and noise that flit to and fro are not nearly as delicate as they might seem. Looking like dainty little fairies in their plumage of sparkly feathers, hummingbirds are really tough old birds that will fight fiercely to defend a territory or fly thousands of miles solo on their annual migration. Don’t let their small size mislead you, for these miniature flyers are really little super heroes in disguise.
Just imagine all you could accomplish if you could move your arms as fast as the wings of the hummingbird. Actual wing speed varies with species, but the hummingbirds that frequent our valley move their wings at an average speed of 40 to 50 beats per second. This incredible speed is achieved from a combination of features.
The hummingbird’s average weight is only about 0.13 ounces, 25 percent to 30 percent of which is pure muscle. Additionally, its shoulder joints have a unique design, allowing them to rotate nearly 180 degrees. This permits the hummingbird to move its wings in a figure-eight pattern, generating power on the upstroke as well as the downstroke. This is what enables the hummingbird to hover and fly in all directions – straight up or down, sideways and even backwards.
Hummingbird migration is legendary, and the eastern ruby-throated hummingbird is famous for its solo flights as far south as Panama. For years, researchers have sought to understand how such a small creature could make such a long journey, particularly because it entails crossing the Gulf of Mexico without stopping.
Stories told by generations past rationalized this feat by explaining that the tiny birds must hitch rides on the backs of more legendary migrators, such as the Canada goose. This story, while still told in some places, is completely untrue for so many reasons, starting with the fact that the geese don’t go anywhere close to the Gulf of Mexico in their migrations.
Since our valley is home to lots of visitors and transplants from the East Coast, it’s common to hear the local hummingbirds called ruby-throats, since the males share the same red gorget as their East Coast cousins. The predominant species of hummingbirds in our valley, though, is the broad-tail. These birds look similar to the ruby-throats but are slightly larger and hardier and are differentiated primarily by their range. The broad-tailed hummingbirds are primarily a Western species, with occasional sightings as far north as British Columbia. These hardy birds typically migrate down to Mexico, or sometimes as far south as Guatemala, where some populations remain all year long. The larger, rusty-colored Rufous hummingbird usually arrives later in summer, stopping in Colorado on its way from the Yucatan Peninsula in Mexico to breeding grounds as far north as Alaska.
Very tiny animals don’t typically fare well in really cold places. These hardy avian champions, though, have developed the ability to enter torpor, or a period of slowed metabolic rate similar to hibernation, during cold spells. During this time, they can lower their heart rate from a typical speed of 500 beats per minute to approximately 50. Body temperatures also decrease dramatically, from a daytime norm of 105 degrees to a nightly average of 50 degrees or so. Additionally, the male broad-tailed hummingbird, free from the obligations of caring for young, typically travels upslope at night, avoiding the cold air trapped in the valleys by thermal inversions. This reduces its overall energy costs by close to 15 percent, which can sometimes mean the difference between life and death. Despite these adaptations, really cold frosts can and do sometimes kill these hardy marvels of nature.
The mighty little hummingbird, smallest of all the vertebrate species, continues to amaze and astound. Recent high-tech, super-slow-motion video of these miniature flyers shows that they fight savagely to defend their territories, even body-slamming one another in order to make their point clear. These miniature birds are also champion migrators, with some species traveling more than 12,000 miles round trip each year. The hummingbird, while small in stature, stands as a testament to the tenacity and brilliance of nature’s work, reminding us that there is beauty, strength and resilience in a world where appearances don’t always tell the whole story.
Jaymee Squires is the director of graduate programs at Walking Mountains Science Center. She enjoys watching the hummingbirds buzz to and fro, but she has given up trying to feed them for this summer.