Hummingbird Facts & Information

Hummingbird facts and information


Hummingbird  Facts & Information


Families 

All hummingbirds belong to the family Trochillidae.

Close Relatives 

They are closely related to the swifts of the family Apodidae.

Conservation

The major threat to hummingbirds is habitat loss. There are 37 species of hummingbirds in the list of threatened and endangered birds.  

Distribution

Hummingbirds occur only in the Americas.

Diet

They feed on mostly nectar from flowers and small soft insects.  

Habitat

Hummingbirds occupy just about every habitat. They occur from coastal deserts, rainforest, and alpine grasslands.


Hummingbird Facts

  1. Hummingbirds are found only in the Americas. They reach their highest diversity in the humid montane forest of the northern Andes where up to 130 species occur in regions of the Andes.
  2. Contrary to what some people believe, a hummingbird cannot switch its colors on and off. They have iridescent or structural colors that vary depending on the arrangement of the feathers and the angle of light.
  3. Hummingbirds have tiny legs and feet that they use to perch and scratch themselves. The Olivaceous Thornbill of the high Andes walks from a flower to a nearby flower to save energy.
  4. Hummingbirds are the smallest birds (about 3 grams of the smallest species), have the lowest number of feathers (about 1400) but have the largest pectoral (flight) muscles proportionally. Well-developed pectoral muscles allow them some of the most acrobatic flight of the avian world.
  5. All hummingbird females are single mothers. After mating with a male, she finds a location for the nest, builds it, lays eggs, and incubates them by herself. After the chick hatch, she raises them alone.
  6. Hummingbirds’ wing beats vary with size. The tiny hummingbirds beat their wings at an approximate rate of 80 times per second whereas the Giant Hummingbird of the Andes does so at a rate of 12 beats per second.
  7. Hummingbirds can live up to 12 years based on banded and recaptured birds.
  8. Hummingbirds have excellent eyesight and can differentiate the sugar concentration in nectar. However, they have a poor sense of smell.
  9. While it is uncertain whether they used their bill, hummingbirds are very aggressive to other birds in the air. They chase away much larger birds such as mockingbirds, blue jays, and even hawks.
  10. Some species of Andean hummingbirds have co-evolve with the length and shapes of flower resulting in bizarre bill shapes and lengths.


Table of Content



Origin of Hummingbirds 

Current geographic distribution and diversity of hummingbirds suggest that they split into many species in the Andean Mountains of South America. The process of speciation might have been speeded up by the geological transformation of the Andean Mountains.

As new species emerged, mutualistic plant-hummingbird relationships were forged resulting in species with bills of lengths and shape specific to a particular group of flowers. Currently, as many as 135 species of hummingbird occur and partition resources in some localities in the Andes.

There are about 360 known species of hummingbirds, which makes them the second-greatest number of species of any bird family, after the tyrant flycatchers.

Hummingbirds are closely related to the insectivorous swifts of the family Apodidae. Studies on the evolution of hummingbirds suggest that they split from the swifts. Hummingbirds and swifts share having very short legs, used only for perching, and long wings. Some taxonomists place the hummingbirds and swifts within the order of Apodiformes; others place them in the Trochiliformes.

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Hummingbird Diversity

With 360 species, the hummingbirds are the second most diverse family of birds in the world after the tyrant flycatchers. Hummingbirds occur only in the Americas from Alaska to Tierra del Fuego in Chile and occupy just about every habitat from sea level up to snow line.

They reach the highest species diversity in the subtropical montane forests of the northern Andes near the Equator. From here, species richness tapers off in all directions. For instance, 25 species of hummingbirds have been recorded from the United States and fewer than ten from Canada and Chile in extreme South America. The country of Colombia alone has more than 160 species, and the tiny nation of Ecuador has about 130 species.

DNA analyses indicates that the basal hummingbird assemblages originated in the lowlands of South America, that most of the main clades of hummingbirds (all but Mountain Gems and possibly Bees) originated on this continent, and that there have been many (at least 30) independent invasions of other primary landmasses, especially Central America.

Studies indicate that hummingbirds originated in the lowlands of South America. DNA and associated genetic markers suggest that hummingbirds can be group in nine broad groups known as the:

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hummingbird diversity

Hummingbird Vocalizations

Hummingbirds are not great singers. While only a few species can sing, most hummingbirds give monotonous series of calls chirps, squeaks or a combination of these. Some species vocalize mostly early in the morning while others do so throughout the day.

During chases and interactions, hummingbirds produce a different type of chirps and squeaks. Many hummingbirds can produce sounds by making their tail and wing feathers vibrate against the air usually during dives.

Vocalizations of the Anna’s Hummingbird (Calypte anna)

Song

Calls

Flight Calls

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Breeding

Hummingbirds have a rather peculiar reproductive biology. During the breeding season, a male hummingbird can mate with as many females as possible in a mating system called Polygamy. After mating, the male moves on and may never see the female again. The female also moves on and builds a nest and raise the young by herself.

It can be said that every female hummingbird is a single mother. After mating, she begins the process of building the nest. She will gather small pieces of bark, twigs, dead leaves binding them with spider web to form a cup-shaped nest.

The female then lays two tiny white eggs that weigh only 0.4 grams on average. The Giant Hummingbird’s egg weighs approximately 1.4 grams. For comparison, a large chicken egg weighs about 40 times as much as a hummingbird egg.

Depending on the species and average temperature, a female hummingbird incubates the eggs for 14 to 23 days. The mother collects insects and nectar to feed her nestlings by inserting her bill into the chick’s crop to regurgitate food. The young hummingbirds are altricial and fledge (leave the nest) approximately 18 to 28 days after hatching.

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Female Anna’s hummingbird built her nest.

The Nest of Hummingbirds

hummingbird nesting biology

The nest is placed on a branch or the upper or underside of broad leaves. As a final touch, the female collects pieces of lichens, moss, dead leaves, and other items to line the outer walls of the nest to help it blend in with the surroundings. Some species attach twigs and pieces of leaves haphazardly to make the nest look like a natural accumulation of leaf litter.

Nest of a White-bellied Hummingbird (Amazilia chionogaster)

Sexual Dimorphism in Hummingbirds

In most species of hummingbirds, males are brightly colored, have fancy tails, and iridescent gorgets. Conversely, the females are often gray, brown, or dull green with simple square tails. In some species, males and females are very similar, and it is challenging to tell sexes apart based on plumage appearance.

In all species, immature birds, typically resemble females in that they have no bright colors.

In some species males and females show differences in body size and bill length and shape. Ornithologists suggest that these differences may enable one sex to use flowers that the other sex is not interested in, hence minimize the competition for resources.

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Flight Adaptations

The flight abilities of hummingbirds have fascinated ancient cultures as well as bird enthusiasts and scientist. No other bird comes close to be able to fly at full speed and stop in midair to hover then make a summersault to disappear as quickly as it appeared.

In some regards, their flight mechanics resemble those of an insect rather than that of a bird.

Many birds are capable of hovering for short periods, but the mechanics used by hummingbirds to hover for a long time with such ease and control are unique to them. Hummingbirds have proportionally larger pectoral (chest) muscles and very low stress in the muscles involved in flight.

Their sophisticated chest and wing muscles allow hummingbirds to pivot their wings 180 degrees at the shoulder tracing a horizontal figure eight at each wingbeat cycle. Hummingbirds can beat their wings asynchronously, which enables them to rotate and change direction instantly.

This type of flight control is more closely associated with insects such as dragonflies than with birds and is a unique adaptation that hummingbirds have adopted for efficient flight. For their tiny size, hummingbirds have an enlarged heart for more efficient oxygen distribution to the muscles enabling them faster wing beats for an extended period.

The number of wingbeats per second depends on the size of the hummingbird and range from 12 in the Giant Hummingbird of the Andes to 80 in most small hummingbirds.

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Courtship Display

Hummingbirds perform aerial courtship displays, typically, ascending then rapidly diving at incredibly fast speed. Studies of the Anna’s Hummingbird recorded a downward velocity of 27 miles per second during a dive over a female; this speed is the highest reported for any vertebrate. For comparison, this is about twice the diving speed of a peregrine falcon in pursuit of prey.

Some hummingbirds produce a high-pitched sound at the bottom of the dive. The sound is caused by the aerodynamics of rapid airflow past the expanded outer tail feathers, causing them to flutter in a vibration which produces the high-pitched sound.

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Co-evolution with Flowers

Hummingbirds feed mostly on nectar from flowers and supplement their diet with insects. Most species have straight or slightly curved bills and are not specialized in a particular type of flowers.

Others have co-evolved with a much narrower set of flower types and have developed long and curved, bills, very short and thin, sickle-like, and extremely long measures. Bills that fit a flower’s shape and depth of the corolla are better able to obtain nectar from those flowers.

adaptation of hummingbirds
White-tipped Sicklebill (Eutoxeres aquila) (left) and Sword-billed Hummingbird (Ensifera ensifera) (right).

Hummingbirds can see a broader spectrum of colors than insects, hence can locate more flowers than insects visually. Flowers that attract hummingbirds as pollinators produce a relatively weak (low sugar content) nectar perhaps to have hummingbirds returning to the flower for more. Hence, increasing the plant’s probability of being cross-pollinated.

Flowers that have insects as cross-pollinators produce nectar with an even higher concentration of nectar in low volumes. Sweeter nectar appears to keep insects inside the flower for an extended time, increasing the plant’s probability of cross-pollination.

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Diet Specialization

There is a misconception that hummingbirds feed exclusively on nectar. While nectar is an essential part of a hummingbird’s diet, they take a substantial amount of mosquitos, gnats, fruit flies, and spiders.

Nectar is produced by flowers to attract mainly birds and insects to serve as cross pollinators. However, nectar is deficient in nutrients hence the need to supplement their diet with insects.

Hummingbirds have a well-developed sense of taste and can tell nectar with various concentration of sugar and consequently, energetic value. Studies have found that hummingbirds prefer flowers with high sugar concentration and will ignore flowers that offer nectar of less the 10% concentration in sugar concentration.

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Energy Saving Mechanism: Torpor

Torpor is a state of physical lethargy that animals use as a mechanism to save energy. During a state of inactivity, the internal processes in the body slow down to a minimum, thereby saving energy.

Hummingbirds are endotherms, which means that they must generate their body heat to keep warm. Since they can’t see and feed on energy-rich nectar at night, using energy to stay warm could lead to death. As a response, they enter a state of dormancy dropping their body temperature from 40 to 18 °C their heart rate from 1000 heartbeats per minute during the day down to 50 -180 pulses during torpor. During torpor, hummingbirds use 5-30 percent of the energy they would typically use while active.

A hummingbird in torpor is unable to respond to external stimuli for 10-20 minutes, but this varies among species.

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Vision

Hummingbirds have an exceptional vision capable of processing features, shapes, and complex information. Scientists have found that hummingbirds have developed a dense array of retinal neurons that allows them a refined dynamic vision. They can process detailed frontal and lateral view information while hovering or flying.

Dynamic vision explains how hummingbirds flying fast through the forest suddenly stop and check small red or near red objects on people’s hats or clothing. This refined, compelling vision enables hummingbirds to find small flowers in the landscape.

Hummingbirds obtain nectar from red, pink, and orange flowers and have no problem visiting flowers of other colors as long as they offer good quality nectar. Experimental studies suggest that hummingbirds relied little on flower colors to find nectar. Instead, they used surrounding landmarks to locate patches of flowers that offer plenty of nectar.

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Lifespan

Hummingbirds have a relatively long lifespan. Small animals with high metabolic rates tend to have very short lifespans. Such is the case of mammals like shrews and small mice with lifespans of about two years. Hummingbirds are tiny and have high metabolic rates; therefore, it would be expected that their lifespans are even shorter, but this is not the case.

Hummingbirds banded and recaptured in North America show that they can live for as long as 11 to 12 years. Nothing is known about the lifespan of hummingbirds in the tropical region but would be expected to have similar lifespans.

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Plumage Color

The iridescent colors of hummingbirds are not produced by pigments -like in most birds- but are structural colors. Structural colors are produced by light reflected by microscopic structures encased in layers on the feather surface. The microscopic structures form a mosaic of platelets of elliptical form. Each platelet is tiny and consists of air bubbles encased in a refractive coating.

structural colors of hummingbirds
Velvet Purple Coronet (Boissonneaua jardini)

The microscopic structures that produce iridescent colors are rather complex. The light must past through the layers containing the platelets and reflects an iridescent color.

Explained simplistically, this is how hummingbird’s gorgets can turn from red to orange or look entirely black depending on the orientation of the feathers relative to the light. Ornithologists have found that birds with access to better diets tend to have brighter colors than those with poor diets.

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Hummingbird Migration

Little is known about the migration patterns of tropical hummingbirds. Fruit-eating birds (frugivorous) are known to move within the tropical region following the availability of fruit. Hummingbirds are likely to move regionally following the availability of flowers and insect, but there is little to no documentation of such movements.

In North America, the northward migration of rufous hummingbirds (Selasphorus rufus) along the Pacific flyway of western United States appears to be timed with flower and tree leaf emergence and the appearance of insects in spring. The Peruvian Sheartail (Thaumastura cora) and Purple-collared woodstar (Mirtys fanny) descent from the western Andes to coastal lowlands of Peru and Chile during the southern hemisphere summer months of January, February, and March during the time flowers and insects are more available in the lowlands.

The hummingbirds that breed in the United States and Canada migrate south to Mexico and Central America during the wintertime. The rufous hummingbird covers the longest migration journey from its nesting ground in northern North America and Alaska 3,900 miles south to its wintering grounds in Mexico and Central America. Other North American hummingbirds travel shorter distances and some winter in the warmer Southwest States and Florida.

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Feeding Adaptations

When it comes to feeding adaptations, hummingbirds have developed bills with lengths and shapes suitable to feed on nectar and insects. Unlike other birds, hummingbirds have a lower mandible that can be flexed downward up to 25 degrees allowing the gape to widen and act as a basket to catch flying insects. To ensure that nectar is not waisted while feeding, the lower mandible of a hummingbird’s bill fits perfectly inside the upper mandible or maxilla.

The majority of hummingbird species have straight or slightly decurved bill and vary greatly in length. These hummingbirds can access the nectar of many types of flowers.

A smaller group of hummingbirds have co-evolved with a particular group of flowers. For instance, the thornbills have a very short and straight bill measuring about 5 millimeters and obtain nectar from flowers with short corolla. On the other extreme is the sward-billed hummingbirds with a bill length of about 100 mm specialized on flowers of very long corollae. In between, are the sicklebills with an extremely curved bill specialized on flowers of the genera Centropogon and Heliconia. The hermits of the family Phaethornis sp. have very long bills that vary in curvature and appear to prefer different types of flowers.

Hummingbirds have evolved sweet sensory receptors that enable them to taste the sugar concentration of flowers. This advantage facilitates their search and exploitation for the best patches of nectar-bearing flowers and the selection of the best migration routes and nesting areas.

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Tongue Adaptations

The tongue of a hummingbird is specially adapted to suction nectar from deep inside a flower. The tongue has tiny pipes that run along the length of it. These pipes open on the sides as the bird reaches for the nectar and quickly fill up de pipes and close the tubes as the tongue is retracted to unload the nectar inside the bird. This process is repeated rapidly as the bird keeps its bill inside the flower.

Keeping the Balance Between Activity and Food

When it comes to keeping enough fuel to support daily activities, hummingbirds walk a fine line. Because of their high metabolism, hummingbirds are at risk of starving to death if there is not enough food available. To minimize the risk of starvation, hummingbirds have developed the capacity to map in their brains the sources of food they can rely on. Many maintain daily routes that include sources of nectar and insects and often guard and chase other hummingbirds away from patches of flowers.

Their well-developed sense of taste allows them to identify the patches with flowers that offer nectar with a high concentration of sugar. Hummingbirds run their feeding routes multiple times a day, as they need many small meals and can consume half their weight in nectar each day.

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Metabolism in Hummingbirds

Hummingbirds have a high metabolism, which means that they burn energy from food at a faster rate than a similar-sized animal. They require the high-energy content of nectar and the protein of insects to meet the demands needed for the rapid wing beat during hovering and fast forward flight.

Studies have shown that a hummingbird’s heart rate can reach as high as 1,260 beats per minute, and they can breathe at a rate of 250 breaths per minute, even at rest. During the flight, oxygen consumption per gram of muscle tissue in a hummingbird is exceptionally high.

Hummingbirds are capable of rapidly converting ingested sugar to energy to perform daily activities. Being able to make this rapid conversion allows them to overeat and convert food into fat reserves needed to fuel their primary activities in times of food scarcity.

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Hummingbird Activity

Another misconception is that hummingbirds are a hyperactive, restless tiny flying machines, but this is not entirely true. While they fly fast and perform amazing moves in the air, they spend the majority of the time perched on branches preening themselves. Studies that measured the activity of hummingbirds found that they spend an average of 75 to 80 percent of the time perched on branches and an average time of 10 to 15 percent of the time eating nectar and catching insects.

Feeding Hummingbirds

Hummingbirds readily take sugar-water put for them by bird enthusiasts. Hummingbirds get used to the presence of humans who observe them and enjoy their beauty and acrobatic movements at close range.

The most common nectar formula to feed hummingbirds is a solution with a ratio of 1 part of white granulated sugar to 4 parts of water. This mix results in a concentration of 25 percent, which mimics the concentration found in nectar from flowers.

Nectar of varying concentrations of sugar is offered to hummingbirds. Birds prefer and defend feeders containing nectar with high sugar content.

feeding of hummingbirds
White-bellied Woodstar (Chaetocercus mulsant)

Using organic or brown sugar is not recommended to prepare nectar for hummingbirds because they contain elements that can be harmful to hummingbirds.

Some bird enthusiasts feed hummingbirds with red nectar by adding red food dye to the mix. This is unnecessary as nectar from flowers is clear, and hummingbirds do not see inside the flowers. It is best to prepare the nectar oneself using only white granulated sugar without dye and other preservatives contained in mixes sold in stores. Coloring and preservative additives to nectar fed to hummingbirds can harm them.

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References:

  • All About Birds: https://www.allaboutbirds.org/guide/browse/taxonomy/Trochilidae 
  • Birds of Peru (Princeton Field Guides), 2010. by Thomas S. Schulenberg, Douglas F. Stotz, Daniel F. Lane, John P. O’Neill, and Theodore A. Parker. Princeton University Press.Martinez del Rio C., Baker H.G., Baker I. Ecological and evolutionary implications of digestive processes: Bird preferences and the sugar constituents of floral nectar and fruit pulp. Experientia.
  • Powers D.R., Nagy K.A. Field metabolic rate and food consumption by free-living Anna’s hummingbirds (Calypte anna) Physiol. Zool. 1988;61:500–506. 
  • Peru Aves: http://www.peruaves.org/trochilidae/ 
  • Skutch, Alexander F. & Singer, Arthur B. (1973). The Life of the Hummingbird. New York: Crown Publishers. 
  • Suarez R.K. Hummingbird flight: Sustaining the highest mass-specific metabolic rates among vertebrates. Experientia. 1992;48:565–570. 
  • Von Helversen O., Winter Y. Glossophagine bats and their flowers: Costs and benefits for plants and pollinators. In: Kunz T.H., Fenton B., editors. Bat Ecology. University of Chicago; Chicago, IL, USA: 2003. pp. 346–397.