Hummingbirds (It’s not that they don’t know the words…)
by Tina Mitchell
When I set out to write about a bird species, I think “What’s interesting about this species?” With hummingbirds, though, what isn’t interesting about them? The smallest of all birds, hummingbirds weigh between 0.1 and 0.3 ounces—or about the same as 5 – 15 M&Ms for most of the hummingbirds we see in Colorado. Probably the most striking aspect of hummingbirds is their unique ability to hover, as well as fly forward, backward, side to side, and even upside down for short distances. Their common name arises from the hum of their wings beating faster than the eye can discern—for Colorado hummingbirds, around 50 beats per second. They have very long tongues that can extend far beyond the tips of their bills, unlike most other birds (except for woodpeckers, such as the Northern Flicker). Their bills are uniquely designed to extract nectar from deep within tubular flowers. They don’t suck up nectar, though. instead, they lick it and capillary action then moves the liquid up 2 partial tubes on the sides of their tongues and into their throats. Small insects such as gnats and aphids also make up an important part of their diet, providing protein to supplement the sucrose of nectar. Their hearts beat at 1,250 beats per minute when they are flying; even at rest, the rate is still 250 beats per minute. Yet when it’s cold or food is scarce, a hummingbird can dramatically slow its body functioning through a state of torpor, where its heart rate can drop to 50 beats per minute and its body temperature can fall from ~110° F to 55° F.
The 17 species that breed in the U.S. and Canada represent only about 5% of the more than 320 hummingbird species in the world. (Actually hummingbirds are found only in thewestern hemisphere.) In Colorado, we have 2 breeding species. By far the most common and widespread is the Broad-tailed Hummingbird. Colorado hosts more of these birds than any other state or Canadian province, with 37% of the population found in North America (an estimated 1,400,000 individuals in our state!). One summer, I stumbled on a nesting Broad-tail and we were able to take photos over several weeks as the nestlings matured. Scott Rashid, a local bird bander, recaptured a banded Broad-tail in 2010 that was at least 10 years old. (How many beats had that bird’s heart delivered?) Black-Chinned Hummingbirds breed in some areas of the state as well; a measly 5% of those North American birds summer here. In addition, 2 other species routinely pass through Colorado starting in July—the bright-as-a-new-penny Rufous Hummingbird and the diminutive Calliope Hummingbird (the smallest breeding bird in North America).
In our area, hummingbirds migrate, heading to Mexico or Central America for the winter. Rufous Hummingbirds that breed in coastal Alaska routinely fly ~2,700 miles from their wintering grounds to their breeding areas—in effect, traveling 49,000,000 body lengths twice a year. The Calliope Hummingbird holds the record as the smallest long-distance avian migrant in the world. Records show that some Calliopes travel more than 5,000 miles annually on their round-trip migration path to and from central Mexico.
So keep your eyes and ears peeled for increasing numbers of hummingbirds starting in July. By late September into October, the numbers drop dramatically. If you put out hummingbird feeders, early fall is an important time to keep them full. The latecomers are most likely this year’s young and can really use the extra nutrition as summer’s wildflowers fade. Some people worry that keeping feeders up at the end of the season will prevent hummingbirds from leaving for wintering grounds. No problems! The birds will indeed migrate. And a fresh feeder of sugar water—no red dye, please!—can really help in making that long trek a bit easier.