Bird Tawk by Tina Mitchell
Hummingbirds—It’s Not That They Don’t Actually Know the Words…
I write about the natural history of birds for a variety of audiences. When I set out to write about a species, I think “What is 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 (2.5 – 8 grams)—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 and extraordinary ability to hover in the air, 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 ~110o F to 55o 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 the western hemisphere.) In Colorado, we have 2 breeding species. By far the most common and widespread is the Broad-tailed Hummingbird. Colorado is number 1 of all states and Canadian provinces, with 37% of the population found in North America (an estimated 1,400,000 individuals in our state!). Interestingly, Scott Rashid, a local bird bander, recaptured a banded Broad-tail in 2010 that was at least 10 years old. (How many beats has that bird’s heart delivered?) Black-chinned Hummingbirds breed in some areas as well; Colorado has a measly 5% of the North American birds at a mere 110,000 individuals. In addition, 2 other species routinely pass through Colorado starting in July—the more northerly breeding Rufous Hummingbird and Calliope Hummingbird. Males arrive first, followed a few weeks later by females and this year’s young.
Broad-tailed Hummingbirds look a lot like the eastern Ruby-throated Hummingbird because of their brilliant red gorgets (feathers on the throat). However, Ruby-throats are uncommon in Colorado, although a report comes in from the Eastern plains now and then. Instead, Broad-tails are actually more closely related to the brilliant orange-red Rufous Hummingbird.
In contrast, the dark-headed Black-chinned Hummingbirds are in the same genus as the Ruby-throats, even though they don’t look that much alike. (The photo in the link above is extraordinary in that you can actually see the blue/purple “collar” at the end of the black “chin.” It’s very difficult to see that characteristic unless you have the perfect light.) Finally, in still another genus, the Calliope Hummingbird is the smallest breeding bird in North America; both males and females can be identified by their tiny size (only 3” long!) and very short tails (that don’t extend beyond the wingtips at rest). Males have dramatic magenta gorget feathers that look like streamers; as a result, the Calliope always seems to be facing into a headwind.
In our area, hummingbirds are migratory, 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. In fact, a Rufous Hummingbird banded in January, 2010 in Tallahassee, Florida was recaptured in June, 2010 in Chenega Bay, Alaska—roughly 3,530 miles away! 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 central Mexico.
A hummingbird male’s role in breeding is quite clear—mate with as many females as he can and then spend the rest of his summer days defending food sources for himself (or, for those breeding far north, such as the Rufous and Calliopes, get outta town for more southerly climes). Females raise the young alone, building tiny nests of thistle and dandelion down, hair, feathers, and rootlets, with lichen or small bits of bark as camouflage. Spider webs provide the glue for these components—and also allow the tiny nests to stretch to accommodate the growing nestlings. Eggs (usually 2) are about the size of a small jelly bean. The young hatch after 16 – 19 days and leave the nest around 20 days after hatching. We stumbled on a nesting Broad-tailed Hummingbird a few years ago and were able to photograph the nestlings for a few weeks. You can see this series of photos of the nest and nestlings here.
These fascinating creatures have spawned a number of “wives’ tales,” ranging from the harmless (e.g., hummingbirds will starve if I don’t keep my feeders full) to the totally bizarre (e.g., hummingbirds migrate on the backs of Canada Geese). Click here and help dispel 12 common myths (and enjoy some superb photos) about these amazing little jewels.