Hummingbirds are small birds in the family Trochilidae, native only to the Americas. They are known for their ability to hover in mid-air by rapidly flapping their wings, 15–80 times per second (depending on the species). The Giant Hummingbird's wings beat 8–10 beats per second, the wings of medium sized hummingbirds beat about 20–25 beats per second and the smallest beat 70 beats per second. Capable of sustained hovering, the hummingbird has the ability to fly deliberately backwards (this is the only group of birds able to do so) or vertically, and to maintain position while drinking from flower blossoms. They are named for the characteristic hum made by their wings.
Hummingbirds are attracted to many flowering plants—shrimp plants,
Bee Balm, Heliconia, Butterfly Bush, Hibiscus, bromeliads, cannas,
verbenas, honeysuckles, salvias, pentas, fuchsias, many penstemons.
It is often stated that they are especially attracted to red and
yellow flowers. Once attracted to a garden, flowers of other colors
may become much more attractive to the hummingbirds. The location
and growing season should determine choices of the plants selected
for a garden to attract hummingbirds. They feed on the nectar of
these plants and are important pollinators, especially of
deep-throated flowers. Most species of hummingbird also take
insects, especially when feeding young.
The Bee Hummingbird (Mellisuga helenae) is the smallest bird in the world, weighing 1.8 grams (0.06 ounces) and measuring about 5 cm (2 inches). A more typical hummingbird, such as the Rufous Hummingbird (Selasphorus rufus), weighs approximately 3 g (0.106 ounces) and has a length of 10–12 cm (3.5–4 inches). The largest hummingbird is the Giant Hummingbird (Patagona gigas), with some individuals weighing as much as 24 grams (0.85 ounces) and measuring 21.5 cm (8.5 inches).
Most male hummingbirds take no part in nesting. Most species make a neatly woven cup in a tree branch. Two white eggs are laid, which despite being the smallest of all bird eggs, are in fact large relative to the hummingbird's adult size. Incubation is typically 14–19 days.
The hummingbird is a small bird with a long, thin beak. This elongated beak is one of the defining characteristics of the hummingbird, which, with an extendable, bifurcated tongue, has evolved in order to allow the bird to feed upon nectar deep within flowers. A hummingbird's lower beak also has the unique ability to flex downward to create a wider opening, facilitating the capture of insects in the mouth rather than at the tip of the beak.
Hummingbirds vary in size. The smallest hummingbird, the bee hummingbird, weighs less than 2 g, while giant hummingbirds weigh 19–21 g. Most species, however, weigh 2.5–6.5 g and are 6 –12 cm in length. Hummingbirds bear the most glittering plumage in the bird world. They display sexual dimorphism, as male hummingbirds are usually more brightly colored, while females of most species display more cryptic coloration. Most males have iridescent plumage, in metallic red, orange, green and/or blue. Some have only an iridescent throat patch or cap, while others, such as the Coppery-headed Emerald are entirely iridescent.
Hummingbird flight has been studied intensively from an aerodynamic perspective: Hovering hummingbirds may be filmed using high-speed video cameras.
Writing in Nature, biomechanist Douglas Warrick and coworkers studied the Rufous Hummingbird, Selasphorus rufus, in a wind tunnel using particle image velocimetry techniques and investigated the lift generated on the bird's upstroke and down stroke.
They concluded that their subjects produced 75% of their weight support during the down-stroke and 25% during the up-stroke: many earlier studies had assumed (implicitly or explicitly) that lift was generated equally during the two phases of the wing beat cycle, as is the case of insects of a similar size. This finding shows that hummingbirds' hovering is similar to, but distinct from, that of hovering insects such as the hawk moths.
With the exception of insects, hummingbirds while in flight have the highest metabolism of all animals, a necessity in order to support the rapid beating of their wings. Their heart rate can reach as high as 1,260 beats per minute, a rate once measured in a Blue-throated Hummingbird. They also typically consume more than their own weight in food each day, and to do so they must visit hundreds of flowers daily. At any given moment, they are only hours away from starving. However, they are capable of slowing down their metabolism at night, or any other time food is not readily available. They enter a hibernation-like state known as torpor. During torpor, the heart rate and rate of breathing are both slowed dramatically (the heart rate to roughly 50–180 beats per minute), reducing their need for food.
Studies of hummingbirds' metabolism are highly relevant to the question of whether a migrating Ruby-throated Hummingbird can cross 800 km (500 miles) of the Gulf of Mexico on a nonstop flight, as field observations suggest it does. This hummingbird, like other birds preparing to migrate, stores up fat to serve as fuel, thereby augmenting its weight by as much as 40–50 percent and hence increasing the bird's potential flying time.
Hummingbirds are found only in the Americas, from southern Alaska and Canada to Tierra del Fuego, including the Caribbean. The majority of species occur in tropical Central and South America, but several species also breed in temperate areas. Excluding vagrants, sometimes from Cuba or the Bahamas, only the migratory Ruby-throated Hummingbird breeds in eastern North America. The Black-chinned Hummingbird, its close relative and another migrant, is the most widespread and common species in the western United States and Canada.
Most hummingbirds of the U.S. and Canada migrate to warmer climates in the northern winter, but some remain in the warmest coastal regions. Some southern South American forms also move to the tropics in the southern winter.
The Rufous Hummingbird shows an increasing trend to migrate east to winter in the eastern United States, rather than south to Central America, as a result of increasing survival prospects provided by artificial feeders in gardens. In the past, individuals that migrated east would usually die, but now many survive, and their changed migration direction is inherited by their offspring. Provided sufficient food and shelter is available, they are surprisingly hardy, able to tolerate temperatures down to at least -20 °C (-4 °F).
Traditionally, hummingbirds are placed in the order Apodiformes,
which also contains the swifts. In the Sibley-Ahlquist taxonomy,
hummingbirds are separated as a new order, Trochiliformes, but
this is not well supported by additional evidence. Hummingbirds'
wings are hollow and fragile, making fossilization difficult and
leaving their evolutionary history a mystery. Some scientists
also believe that the hummingbird evolved relatively recently.
Scientists also theorize that hummingbirds originated in South
America, where there is the greatest species diversity. Brazil
and Ecuador contain over half of the known species.
There are between 325 and 340 species of hummingbird, depending on taxonomic viewpoint, historically divided into two subfamilies, the hermits (subfamily Phaethornithinae, 34 species in six genera), and the typical hummingbirds (subfamily Trochilinae, all the others).
The modern diversity of hummingbirds is thought by evolutionary biologists to have evolved in South America, as the great majority of the species are found there. However, the ancestor of extant hummingbirds may have lived in parts of Europe to what is southern Russia today.
Genetic analysis has indicated that the hummingbird lineage diverged from their closest relatives some 35 million years ago, in the Late Eocene, but fossil evidence is limited. Fossil hummingbirds are known from the Pleistocene of Brazil and the Bahamas—though neither has yet been scientifically described—and there are fossils and sub fossils of a few extant species known, but until recently, older fossils had not been securely identifiable as hummingbirds.
In 2004, Dr. Gerald Mayr of the Senckenberg Museum in Frankfurt am Main identified two 30-million-year-old hummingbird fossils and published his results in Nature. The fossils of this primitive hummingbird species, named Eurotrochilus inexpectatus ("unexpected European hummingbird"), had been sitting in a museum drawer in Stuttgart; they had been unearthed in a clay pit at Wiesloch-Frauenweiler, south of Heidelberg, Germany and, because it was assumed that hummingbirds never occurred outside the Americas, were not recognized to be hummingbirds until Mayr took a closer look at them.
Fossils of birds not clearly assignable to either hummingbirds or a related, extinct family, the Jungornithidae, have been found at the Messel pit and in the Caucasus, dating from 40–35 mya, indicating that the split between these two lineages indeed occurred at that date. The areas where these early fossils have been found had a climate quite similar to the northern Caribbean or southernmost China during that time. The biggest remaining mystery at the present time is what happened to hummingbirds in the roughly 25 million years between the primitive Eurotrochilus and the modern fossils. The astounding morphological adaptations, the decrease in size, and the dispersal to the Americas and extinction in Eurasia all occurred during this timespan. DNA-DNA hybridization results suggest that the main radiation of South American hummingbirds at least partly took place in the Miocene, some 12–13 mya, during the uplifting of the northern Andes.
The diet of hummingbirds requires an energy source (typically
nectar) and a protein source (typically small insects).
Providing many plants that carry blooms used by hummingbirds is
the safest way to provide nectar for hummingbirds. Through
careful plant selection, gardens may contain plants that bloom
at different times to attract hummingbirds throughout the
seasons they are present in an area. Placing these plants near
windows affords a good view of the birds. Hummingbirds will take
synthetic nectar from artificial feeders. Such feeders allow
people to observe and enjoy hummingbirds up-close while
providing the hummingbirds with a reliable supply of nectar,
especially when flower blossoms are less abundant. Maintaining
cleanliness of the feeder is essential for the health of the
birds. Homemade nectar can be made from 1 part white, granulated
table sugar to 4 parts water, boiled to make it easier to
dissolve the sugar and to purify the solution so that it will
stay fresh longer. The water should be boiled before measuring
to ensure that the ratio of sugar to water remains 1–4. The
cooled nectar is then poured into the feeder.
Hummingbirds will either hover or perch to feed, and red feeders are preferred. Things to avoid using in feeders include honey, which should not be used because it is prone to culture bacteria dangerous to hummingbirds. Artificial sweeteners should also be avoided because, although the hummingbirds will drink it, they will be starved of the calories they need to sustain their metabolism. Some commercial hummingbird foods contain red dyes and preservatives, which are unnecessary and possibly dangerous to the birds, so dyes and preservatives should be avoided because neither have been studied for long-term effects on hummingbirds. While it is true that bright colors, especially red, initially attract hummingbirds more quickly than others, it is better to use a feeder that has some red on it, rather than coloring the liquid offered in it. It is possible that red dye is harmful to hummingbirds. Commercial nectar mixes may contain small amounts of mineral nutrients which are useful to hummingbirds, but hummingbirds get all the nutrients they need from the insects they eat, not from nectar, so the added nutrients also are unnecessary. Authorities on hummingbirds recommend that if you use a feeder, use just plain sugar and water.
A hummingbird feeder should be easy to refill and keep clean. Prepared nectar can be refrigerated for 1–2 weeks before being used, but once placed outdoors it will only remain fresh for 2–4 days in hot weather, or 4–6 days in moderate weather, before turning cloudy or developing mold. When changing the nectar, the feeder should be rinsed thoroughly with warm tap water, flushing the reservoir and ports to remove any contamination or sugar build-up. If dish soap is used, it always needs extra rinsing so that no residue is left behind. The feeder can be soaked in dilute chlorine bleach if black specks of mold appear and rinsed with clear water.
Other animals are also attracted to hummingbird feeders. It is a good idea to get a feeder that has very narrow ports, or ports with mesh-like "wasp guards", to prevent bees and wasps from getting inside where they get trapped. Orioles, woodpeckers, banaquits, and other animals are known to drink from hummingbird feeders, sometimes tipping them and draining the liquid. If this becomes a problem, it is possible to buy feeders which are specifically designed to support their extra weight and which hummingbirds will use too. If ants find your hummingbird feeder, one solution is to install an "ant moat", which is available at specialty garden stores and online, or tangle foot can be used to trap the ants, provided it is applied in a location totally inaccessible to the hummingbirds. You can also place Vaseline on the pole that holds the feeder to trap ants on the path that they create.
Sometimes a large hummingbird drives its smaller brethren away from a feeder. An effective solution is to put out a second feeder that contains a slightly lower sugar concentration. Hummingbirds can detect a feeding source that is denser in sugar by only a few percent, and the more aggressive bird will make that feeder its own. The smaller birds will flock to the remaining feeder.
This Hummingbird Page is Copyright The Animal Web Guide © 2004 - 2009 Chuck Ayoub