Of a Feather: Mechanical toy in the sky

By BILL CHAISSON
By Bill Chaisson

The August calendar page in the Old Farmer’s Almanac notes that the 24th is St. Bartholomew’s Day and “Hummingbirds migrate south.” I haven’t seen my local ruby-throated since about that date, but someone down in Wilmot Flat reported hummingbirds at his feeder this week. Migrants? The level in my feeder stopped declining two weeks ago.

I have always bemoaned that we have only one hummingbird species in the eastern U.S. The rufous hummingbird (Selasphorus rufus) occasionally wanders east during migration, but the ruby-throated hummingbird (Archilochus colubris) is found from southern Canada to the Gulf Coast and west to the Great Plains, one of the larger ranges in this family. The rufous breeds even further north, ranging up to southeastern Alaska.

When we headed for Colorado last month, I was excited there two species to be seen there. The black-chinned hummingbird (Archilochus alexandri) is the only other member of a genus it shares with the ruby-throated, and the broad-tailed hummingbird (Selasphorus platycercus) is “bee hummingbird” like the rufous. The latter group is characterized by much rufous on the body and orange to purple gorgets.

The gorget is the patch of bright-colored feathers on the throats of the males. The feather color appears to change in the light; it is produced by refraction through translucent cell structure rather than pigment in the feathers. Sibley goes as far as to illustrate the males twice, once with the bright refractive color and once with the dark. In the latter illustrations, the ruby-throated and black-chinned are almost identical.

Both the black-chinned and the broad-tailed are broadly distributed and common in the west, but I only ever saw the broad-tailed. This was mostly due to the incredibly loud and strange sound their wings make. At home I am often startled by the hum of a ruby-throat’s wings because it sounds like a very large insect. Apparently, its cousin the black-chinned produces a similar sound.

The broad-billed, however, produces a sound that has an almost science-fiction quality to it. Sibley describes it as resembling the call of a cedar waxwing, which doesn’t do it justice for weirdness. It has a mechanical quality that makes the birds seem like advanced airborne androids (ornithoids?). In fact, the trill is made by two uniquely shaped primaries on the male birds.

I first heard them in the vicinity of our bed and breakfast in Florissant at about 8,200 feet elevation. The species is said to favor “subalpine meadows, foothills, montane valleys” and is found “under tree canopies of pine and oak woodland,” which describes Florissant pretty well. When we ventured into the higher mountains above 9,000 feet, we didn’t see or hear them, although the wildflowers were abundant, and even though allaboutbirds.org says they breed as high as 10,500 feet.

Indeed, we visited Georgetown, Colorado, elevation 8,600 feet, and broad-tailed hummingbirds were ubiquitous. As I walked around in this densely-populated small town tucked into a deep, narrow valley below Interstate 70, I almost felt as if I was under surveillance by tiny tinkling drones. At times you could hear three of them at once, darting around the neighborhoods at rooftop level.

The broad-tailed is the least rufous of the three North American bee hummingbirds. The color is confined to their underwing coverts, sides and two patches on either side of the top of the base of the tail. The male’s gorget is rosy red in good light and purplish in poor light. The female has a broad black band on the tail and the outer tail feathers have prominent white spots at the tips. The black-chinned female has a similar pattern on the tail, but no rufous and a much longer bill.

The broad-tailed is relatively large. At 4 inches long, it has at least a quarter-inch on either the ruby-throated or black-chinned. That might not seem like much, but 6.25% larger is discernible, at least when they are at rest. Their wings are also significantly longer; 5.25 inches versus 4.5 inches for the ruby-throated.

As hummingbirds go, these species are all mid-sized and conservatively appointed. The giant hummingbird of the Andes is over 9 inches long (gray catbirds, for comparison, are 8.5 inches long) and the bee hummingbird of Cuba is only 2 inches long and is the world’s smallest bird. (Because birds are direct descendants of the dinosaurs, the bee hummingbird is also the smallest known dinosaur.)

I remember being confronted by what I believe was a violet sabrewing (Campylopterus hemileucurus) beside a stream next to the Palenque ruins in Chiapas, Mexico. The curve-billed bird—it was the female—hovered about 8 feet above and in front of me and repeatedly emitted a high-pitched squawk. This is the largest hummingbird found outside of South America.

I was astonished at its size, but also by how aggressive it was. I should not have been. Hummingbirds tend to be very aggressive with each other and other birds. I had the impression that the broad-tailed hummingbirds in Georgetown were chasing each other through the trees.

It is not surprising I was confronted by the female sabrewing. Male hummingbirds take no part whatsoever in defending a territory around the nest or helping females with raising the young. In fact, no pairing takes place and male hummingbirds are promiscuous, mating with as many females in a season as they are able.

While the North American Breeding Bird Survey shows the ruby-throated hummingbird numbers increasing every year since 1966, the broad-billed hummingbird has declined by 52 percent in the same time period. Climate changes has caused flowers to bloom progressively earlier in the high mountain meadows, but the birds arrive at the same time in the spring. This shortens the period they have to collect nectar and breed.

Bill Chaisson has been a birdwatcher from the age of 10. He is a former managing editor of the Eagle Times and now lives and works in the town of Wilmot. Contact him at [email protected].