As many of you know, Jane Thompson and I have been spending time the past few years at Darwin and Eileen Lambert’s Shaver Hollow home (home of Tulip Tree cabin). It’s a fascinating place of fruit trees, vegetables and perennials, copperheads and frogs. It’s also a wonderful place to observe our one species of hummingbird here in the east; the ruby-throated hummingbird. Eileen maintains four feeders around her house, with the daily consumption of a quart and a half of sugar water by dozens of hummers who take advantage of her hospitality.
Hummingbirds are such special animals. So small, fast, and unlike any other bird you’ve ever seen. They seem to like to get up in your face, a function of their near-sightedness. In fact, if you remain still, hummers have been known to stick their beaks into your ear.
They are only found in the New World, but the 338 species range from Alaska to Tierra del Fuego on the southern tip of South America. It is believed they originated in the equatorial region, where more than half the known species are found within a ten degree wide belt in South America, and have spread out from there. When Europeans first established trade between the New and Old Worlds, hummingbird pelts were among the valued items of commerce for jewelry and adornments for women’s hats. Early in the 19th century, one London dealer imported more than 400,000 skins in one year from the West Indies alone.
Of the 8,700 species of birds, only the hummingbird can fly backwards. Another remarkable feat of the hummingbird is flying upside down. If suddenly assailed from the front, as while visiting a flower, it may turn a backward somersault by flipping its spread tail forward, dart a short distance with its wings in reverse and feet upward, then roll over and continue in normal flight. Yet, they cannot soar, and most cannot hop or walk. The smallest hummingbird, the Cuban bee hummingbird, approaches the smallest size theoretically possible (Any smaller, and the species couldn’t eat enough to keep up with the required metabolism – Coincidently, this comment has also been applied to the pygmy shrew). It is only 2 ¼” long; half of that being bill and tail. The largest, the Andes giant hummingbird, measures 8 ½”.
While reading about hummers, I find a number of preconceived impressions need to be discussed. For example, we associate hummingbird flowers with the color red. However, only a slight majority of pollinated hummingbird flowers are red. Hummingbirds are attracted to sugar content, regardless of color. Birds see a lot of the same spectrum as humans. Bees tend to see more of the violet end of the spectrum and beyond. North American hummingbird flowers have evolved from bee flowers, with a shift from blue or violet to red. It is suggested that many hummingbird flowers have made this shift for the benefit of the hummingbird; thus, it makes it easier for hummers to find sugar by association.
Hummingbirds are not the fastest fliers. The average speed of hummers is 30 mph, about the same as most songbirds, geese and crows, while chimney swifts soar at 80 mph. The top speed goes to the Peregrine Falcon, which has been recorded at 175 mph. It’s just their petite size that makes their speed seem so impressive.
Nor are hummers solely nectar-drinkers. As a warm-blooded vertebrate, hummingbirds also need to ingest insects (proteins) that can be converted into muscle, feathers, and other body parts. Fats are also necessary, particularly as hummers store energy in preparation for lengthy migratory flights. However, nectar does make up the vast majority or fuel for the hummer. One study found the hummers consumed 2.2 grams of honey and 0.8 grams of insects during the course of a day, or approximately, its own weight.
Did you know, unlike most birds with long arm bones, the hummingbird’s wings are virtually all fingers, with very short arm bones. This enables both the down and up swing of the wing to provide lift for the hummer, while only the down swing propels all other birds. Thus, one complete stroke of the hummer is equivalent to two of other birds. Thus, for birds of comparable size or weight, hummers have a slower wingbeat than many birds.
Our ruby-throated hummingbird winters in Central America or northern South America. This includes a 500 mile 20 hour non-stop journey over the Gulf of Mexico. With the 1,000 miles of migration both north and south of the Gulf, this can result in a 2,500 mile migration for this incredibly small bird. It can (barely) do this by gaining about 40% of its body weight in fat just prior to its migration. As it migrates north, it quite often precedes the first flowers of spring. Its food source is the sap gathered at yellow-bellied sapsucker holes. Studies show the ruby-throated hummingbird visits the sapsucker holes more than the 19 other birds known to use the sapsucker holes. In fact, the hummer uses the sapsucker holes more than the sapsuckers themselves! Not coincidently, the northern range limits of the ruby-throated hummingbird are the same as the sapsucker!
Our breeding population arrives here in mid-April; the males about two weeks before the females. The nest (and all parental care) is provided by the female (the male will be off attempting to spread his genes about). The 2” nest is made of leaf fibers and lichens laced together with spider cobwebs. In size, shape and color, the two eggs resemble navy beans. As the young mature, they literally break down the sides of the nest, ending up with a virtually flat nest. Two broods per season are common in our region. Being polygymous, each brood will be from different males. Although uncommon, female hummers have been observed attending two separate nests; one with young, and the other with eggs.
At this time in September, they will be migrating through this area on their way back to their wintering grounds. While they aren’t known to migrate in flocks, they have been observed in early September in large numbers on the Cranberry Glades boardwalk.
Two more comments about these interesting animals. First, it should be noted that the color of the ruby throat is not the result of color pigmentation, as is the usual case, but rather by structural differences, like soap bubbles, and refraction; as with a prism. The sun has to be behind the observer to get the best coloration, like a rainbow. Thus, it’s not surprising that when the male does its U-shaped flight above the courted female, the male will dive at the female and pull up in the direction of the sun.
Finally, lest you think the hummingbird has an easy lifestyle, recognize its size makes it an easy prey for a surprising number of predators. Baltimore Orioles, which competes with the hummers for nectar, are known to kill hummers. Other interesting predators include praying mantids, large spiders, and even frogs and bass that have been observed leaping out of the water to catch the hummers!
Ruby-throated Hummingbird Life span: 10 years
Average length: 3.5 inches (8.9 cm)
Average weight: 1/8 ounce (3.1 g)
Body temperature: 105°-108°F (40.5°-42.2°C)
Wing beats: 40-80 per second, average about 52, up to 200 during courtship ritual
Respiration: 250 per minute
Heart rate: 250 beats/min resting; 1200 beats/min feeding
Flight speed: 30 mph normal; 50 mph escape; 60 mph dive
Life span: 10 years