Fall Asleep While Learning About Hummingbirds

In this episode of the I Can't Sleep Podcast, drift off to sleep while learning about hummingbirds. These tiny, fascinating birds can flap their wings faster than you can count—but don’t worry, there’s no quiz at the end. We’ll cover their unique traits, favorite flowers, and maybe even a fun fact or two. Perfectly relaxing, just like their gentle hum. Happy sleeping!

Transcript

Welcome to the I Can't Sleep podcast,

Where I read random articles from across the web to bore you to sleep with my soothing voice.

I'm your host,

Benjamin Boster,

And today's episode is from a Wikipedia article titled,

Hummingbird.

Hummingbirds are birds native to the Americas and comprise the biological family Trochility.

With approximately 366 species and 113 genera,

They occur from Alaska to Tierra de Fuego,

But most species are found in Central and South America.

Hummingbirds have varied specialized characteristics to enable rapid,

Maneuverable flight,

Exceptional metabolic capacity,

Adaptations to high altitude,

Sensitive visual and communication abilities,

And long-distance migration in some species.

Among all birds,

Male hummingbirds have the widest diversity of plumage color,

Particularly in blues,

Greens,

And purples.

Hummingbirds are the smallest mature birds,

Measuring 7.

5 to 13 centimeters in length.

The smallest is the 5-centimeter bee hummingbird,

Which weighs less than 2 grams,

And the largest is the 23-centimeter giant hummingbird,

Weighing 18 to 24 grams.

Noted for long beaks,

Hummingbirds are specialized for feeding on flower nectar,

But all species also consume small insects.

They are known as hummingbirds because of the humming sound created by their beating wings,

Which flap at high frequencies audible to other birds and humans.

They hover at rapid wing-flapping rates,

Which vary from around 12 beats per second in the largest species to 80 per second in small hummingbirds.

Hummingbirds have the highest mass-specific metabolic rate of any bird in the world,

And the highest mass-specific metabolic rate of any homeothermic animal.

To conserve energy when food is scarce,

And at night when not foraging,

They can enter torpor,

A state similar to hibernation,

And slow their metabolic rate to one-fifteenth of its normal rate.

While most hummingbirds do not migrate,

Has one of the longest migrations among birds,

Traveling twice per year between Alaska and Mexico,

A distance of about 3,

900 miles.

Hummingbirds split from their sister group,

The swifts and tree swifts,

Around 42 million years ago.

The oldest known fossil hummingbird is Eurotrocholus,

From the Repellian stage of early Eligocene Europe.

Hummingbirds are the smallest known and smallest living avian theropod dinosaurs.

The iridescent colors and highly specialized feathers of many species,

Mainly in males,

Give some hummingbirds exotic common names,

Such as sun gem,

Fairy,

Wood star,

Sapphire,

Or sylph.

Across the estimated 366 species,

Hummingbird weights range from as small as 2 grams to as large as 20 grams.

They have characteristic long,

Narrow beaks,

Bills,

Which may be straight,

Of varying lengths,

Or highly curved.

The bee hummingbird,

Only 6 centimeters long,

And weighing about 2 grams,

Is the world's smallest bird and smallest warm-blooded vertebrate.

Hummingbirds have compact bodies with relatively long,

Blade-like wings,

Having anatomical structure enabling helicopter-like flight in any direction,

Including the ability to hover.

Particularly while hovering,

The wing beats produce the humming sounds,

Which function to alert other birds.

In some species,

The tail feathers produce sounds used by males during courtship flying.

Hummingbirds have extremely rapid wing beats as high as 80 per second,

Supported by a high metabolic rate,

Dependent on foraging for sugars from flower nectar.

Their legs are short,

With feet having three toes,

Pointing toward and one backward,

The hallux.

The toes of hummingbirds are formed as claws,

With ridged inner surfaces,

To aid gripping onto flower stems or petals.

Hummingbirds do not walk on the ground or hop like most birds,

But rather shuffle laterally and use their feet to grip while perching,

Preening feathers,

Or nest building by females,

And during fights to grab feathers of opponents.

Hummingbirds apply their legs as pistons for generating thrust upon taking flight,

Although the shortness of their legs provides about 20 percent less propulsion than assessed in other birds.

During flight,

Hummingbird feet are tucked up under the body,

Enabling optimal aerodynamics and maneuverability.

Of those species that have been measured during flight,

The top flight speeds of hummingbirds exceed 15 meters per second.

During courtship,

Some male species dive from 30 meters of height above a female at speeds around 23 meters per second.

The sexes differ in feather coloration,

With males having distinct brilliance in ornamentation of head,

Neck,

Wing,

And breast feathers.

The most typical feather ornament in males is the gorget,

A bib-like iridescent neck feather patch that changes brilliance with the viewing angle to attract females and warn male competitors away from territory.

Some species of sunbirds,

An old world group restricted in distribution to Eurasia,

Africa,

And Australia,

Resemble hummingbirds in appearance and behavior,

But are not related to hummingbirds,

As their resemblance is due to convergent evolution.

The hummingbird moth has flying and feeding characteristics similar to those of a hummingbird.

Hummingbirds may be mistaken for hummingbird hawk moths,

Which are large flying insects with hovering capabilities and exist only in Eurasia.

Hummingbirds are restricted to the Americas from south-central Alaska to Tierra del Fuego,

Including the Caribbean.

The majority of species occur in tropical and subtropical Central and South America,

But several species also breed in temperate climates,

And some hill stars occur even in alpine Andean highlands at altitudes up to 52 degrees.

The greatest species richness is in humid tropical and subtropical forests of the northern Andes and adjacent foothills,

But the number of species found in the Atlantic Forest,

Central America,

Or southern Mexico also far exceeds the number found in southern South America,

The Caribbean Islands,

The United States,

And Canada.

While fewer than 25 different species of hummingbirds have been recorded from the United States,

And fewer than 10 from Canada and Chile each,

Colombia alone has more than 160,

And the comparably small Ecuador has about 130 species.

The Andes Mountains appear to be a particularly rich environment for hummingbird evolution because diversification occurred simultaneously with mountain uplift over the past 10 million years.

Hummingbirds remain in dynamic diversification inhabiting ecological regions across South America,

North America,

And the Caribbean,

Indicating an enlarging evolutionary radiation.

Within this same geographic region,

Hummingbird clades co-evolved with nectar-bearing plant clades,

Affecting mechanisms of pollination.

The same is true for the sword-billed hummingbird,

One of the morphologically most extreme species,

And one of its main food plant clades.

Hummingbirds are specialized nectarivores tied to the ornithophilous flower upon which they feed.

This co-evolution implies that morphological traits of hummingbirds,

Such as bill length,

Bill curvature,

And body mass,

Are correlated with morphological traits of plants,

Such as corolla length,

Curvature,

And volume.

Some species,

Especially those with unusual bill shapes,

Such as the sword-billed hummingbird and the sicklebills,

Are co-evolved with a small number of flower species.

Even the most specialized hummingbird plant mutualisms,

The number of food plant lineages of the individual hummingbird species increases with time.

The bee hummingbird,

The world's smallest bird,

Evolved to dwarfism likely because it had to compete with long-billed hummingbirds,

Having an advantage for nectar foraging from specialized flowers,

Consequently leading the bee hummingbird to more successfully compete for flower foraging against insects.

Many plants pollinated by hummingbirds produce flowers in shades of red,

Orange,

And bright pink,

Although the birds take nectar from flowers of other colors.

Hummingbirds can see wavelengths into the near-ultraviolet,

But hummingbird pollinated flowers do not reflect these wavelengths as many insect pollinated flowers do.

This narrow color spectrum may render hummingbird pollinated flowers relatively inconspicuous to most insects,

Thereby reducing nectar robbing.

Hummingbird pollinated flowers also produce relatively weak nectar containing a high proportion of sucrose,

Whereas insect pollinated flowers typically produce more concentrated nectars dominated by fructose and glucose.

Hummingbirds and the plants they visit for nectar have a tight co-evolutionary association,

Generally called a plant-bird mutualistic network.

These birds show high specialization and modularity,

Especially in communities with high species richness.

These associations are also observed when closely related hummingbirds,

Such as two species of the same genus,

Visit distinct sets of flowering species.

The hummingbird plumage coloration gamut,

Particularly for the blue,

Green,

And purple colors in the gorget and crown of males,

Occupies 34% of the total color space for bird feathers.

White,

Unpigmented feathers have the lowest incidence in the hummingbird color gamut.

Hummingbird plumage color diversity evolved from sexual and social selection on plumage coloration,

Which correlates with the rate of hummingbird species development over millions of years.

Bright plumage colors in males are part of aggressive competition for flower resources and mating.

The bright colors result from pigmentation in the feathers and from prismal cells within the top layers of feathers of the head,

Gorget,

Breast,

Back,

And wings.

When sunlight hits these cells,

It is split into wavelengths that reflect the observer in varying degrees of intensity,

With the feather structure acting as a diffraction grating.

Iridescent hummingbird colors result from a combination of refraction and pigmentation,

Since the diffraction structures themselves are made of melanin,

A pigment,

And may also be colored by carotenoid pigmentation and more subdued black,

Brown,

Or gray colors dependent on melanin.

By merely shifting position,

Feather regions of a muted-looking bird can instantly become fiery red or vivid green.

In courtship displays,

For one example,

Males of the colorful anise hummingbird orient their bodies and feathers toward the sun to enhance the display value of iridescent plumage toward a female of interest.

One study of anise hummingbirds found that dietary protein was an influential factor in feather color,

As birds receiving more protein grew significantly more colorful crown feathers than those fed a low-protein diet.

Additionally,

Birds on a high-protein diet grew yellower,

Higher-hue green tail feathers than birds on a low-protein diet.

Hummingbirds are named for the prominent humming sound their wingbeats make while flying and hovering to feed or interact with other hummingbirds.

Humming serves communication purposes by alerting other birds of the arrival of a fellow forager or potential maid.

The humming sound derives from aerodynamic forces generated by the downstrokes and upstrokes of the rapid wingbeats,

Causing oscillations and harmonics that evoke an acoustic quality likened to that of a musical instrument.

The humming sound of hummingbirds is unique among flying animals,

Compared to the whine of mosquitoes,

Buzz of bees,

And whoosh of larger birds.

The wingbeats causing the hum of hummingbirds during hovering are achieved by elastic recoil of wingstrokes produced by the main flight muscles.

The pectoralis major,

The main downstroke muscle,

And supracorcordius,

The main upstroke muscle.

Although hummingbird eyes are small in diameter,

They are accommodated in the skull by reduced skull ossification and occupy a larger proportion of the skull compared to other birds and animals.

Further,

Hummingbird eyes have large corneas,

Which comprise about 50% of the total transverse eye diameter,

Combined with an extraordinary density of retinoganglion cells responsible for visual processing,

Containing some 45,

000 neurons per millimeter squared.

The enlarged cornea relative to eye diameter serves to increase the amount of light perception by the eye when the pupil is dilated maximally,

Enabling nocturnal flight.

During evolution,

Hummingbirds adapted to the navigation needs of visual processing while in rapid flight or hovering by development of the exceptionally dense array of retinal neurons,

Allowing for increased spatial resolution in the lateral and frontal visual fields.

Morphological studies of the hummingbird brain showed that neuronal hypertrophy,

Relatively the largest in any bird,

Exists in a region responsible for the refining dynamic visual processing while hovering and during rapid flight.

The enlargement of the brain region responsible for visual processing indicates an enhanced ability for perception and processing of fast-moving visual stimuli encountered during rapid forward flight,

Insect foraging,

Competitive interactions,

And high-speed courtship.

A study of broad-tailed hummingbirds indicated that hummingbirds have a fourth color-sensitive visual cone,

Humans have three,

That detects ultraviolet light and enables discrimination of non-spectral colors,

Possibly having a role in flower identity,

Courtship displays,

Territorial defense,

And predator evasion.

The fourth color cone would extend the range of visible colors for hummingbirds to perceive ultraviolet light and color combinations of feathers and gorgets,

Colorful plants,

And other objects in their environment,

Enabling detection of as many as five non-spectral colors,

Including purple,

Ultraviolet red,

Ultraviolet green,

Ultraviolet yellow,

And ultraviolet purple.

Hummingbirds are highly sensitive to stimuli in their visual fields,

Responding to even minimal motion in any direction by reorienting themselves in mid-flight.

Their visual sensitivity allows them to precisely hover in place while in complex and dynamic natural environments,

Functions enabled by the lentiform nucleus,

Which is tuned to fast pattern velocities,

Enabling highly tuned control and collision avoidance during forward flight.

Many hummingbird species exhibit a diverse vocal repertoire of chirps,

Squeaks,

Whistles,

And buzzes.

Vocalizations vary in complexity and spectral content during social interactions,

Foraging,

Territorial defense,

Courtship,

And mother-nestling communication.

Territorial vocal signals may be produced in rapid succession to discourage aggressive encounters,

With the chirping rate and loudness increasing when intruders persist.

Hummingbirds exhibit vocal production learning to enable song variation,

Dialects that exist across the same species.

For example,

The blue-throated hummingbird song differs from typical oscine songs in its wide frequency range,

Extending from 1.

8 kHz to about 30 kHz.

It also produces ultrasonic vocalizations which do not function in communication.

As blue-throated hummingbirds often alternate singing with catching small flying insects,

It is possible the ultrasonic clicks produced during singing disrupt insect fly patterns,

Making insects more vulnerable to predation.

Annas,

Costas,

Long-billed hermits,

And Andean hummingbirds have song dialects that vary across habitat locations and phylogenetic clades.

The avian vocal organ,

The syrinx,

Plays an important role in understanding hummingbird song production.

What makes the hummingbird's syrinx different from that of other birds in the apotiform's order is the presence of internal muscle structure,

Accessory cartilages,

And a large tympanum that serves as an attachment point for external muscles,

All of which are adaptations sought to be responsible for the hummingbird's increased ability in pitch control and large frequency range.

Hummingbird songs originate from at least six different species of birds.

Seven specialized nuclei in the forebrain.

A genetic expression study showed that these nuclei enable vocal learning,

Ability to acquire vocalizations through imitation,

A rare trait known to occur in only two other groups of birds,

Parrots and songbirds,

And a few groups of mammals including humans,

Whales and dolphins,

And bats.

Within the past 66 million years,

Only hummingbirds,

Parrots,

And songbirds out of 23 bird orders may have independently evolved seven similar forebrain structures for singing and vocal learning,

Indicating that evolution of these structures is under strong epigenetic constraints,

Possibly derived from a common ancestor.

Generally,

Birds have been assessed to vocalize and hear in the range of two to five kilohertz,

With hearing sensitivity falling with higher frequencies.

In the Ecuadorian hill star,

Vocalizations were recorded in the wild to be at a frequency above 10 kilohertz,

Well outside of the known hearing ability of most birds.

Song systems are often used to record the vocal range of a bird,

Song system nuclei in the hummingbird brain are similar to those songbird brains,

But the hummingbird brain has specialized regions involved for song processing.

Hummingbirds have the highest metabolism of all vertebrate animals,

A necessity to support the rapid beating of their wings during hovering and fast forward flight.

During flight and hovering,

Oxygen consumption per gram of muscle tissue in a hummingbird is about 10 times higher than that measured in elite human athletes.

Hummingbirds achieve this extraordinary capacity for oxygen consumption by an exceptional density and proximity of capillaries and mitochondria in their flight muscles.

Hummingbirds are rare among vertebrates in their ability to fly,

And their ability to rapidly make use of ingested sugars to fuel energetically expensive hovering flight,

Powering up to 100% of their metabolic needs with the sugars they drink.

To sustain rapid wing beats during flight and hovering,

Hummingbirds expend the human equivalent of 150,

000 calories per day,

An amount estimated to be 10 times the energy consumption by a marathon runner in competition.

Hummingbirds can use newly ingested sugars to fuel hovering flight within 30 to 45 minutes of consumption.

These data suggest that hummingbirds are able to oxidize sugar in flight muscles at rates rapid enough to satisfy their extreme metabolic demands,

As indicated by a 2017 review showing that hummingbirds have in their flight muscles a mechanism for direct oxidation of sugars into maximal ATP yield to support a high metabolic rate for hovering,

Foraging at altitude,

And migrating.

By relying on newly ingested sugars to fuel flight,

Hummingbirds reserve their limited fat stores to sustain their overnight fasting during torpor or to power migratory flights.

Studies of hummingbird metabolism address how a migrating ruby-throated hummingbird can cross 800 kilometers of the Gulf of Mexico on a non-stop flight.

This hummingbird,

Like other long-distance migrating birds,

Stores fat as a fuel reserve,

Augmenting its weight by as much as 100%,

Then enabling metabolic fuel for flying over open water.

The amount of fat used by a migrating hummingbird to cross the Gulf of Mexico in a single flight is similar to that used by a human climbing about 50 feet.

The heart rate of hummingbirds can reach as high as 1,

260 beats per minute.

A rate measured in a blue-throated hummingbird with a breathing rate of 250 breaths per minute at rest.

The high metabolic rate of hummingbirds,

Especially during rapid forward flight and hovering,

Produces increased body heat that requires specialized mechanisms of thermal regulation for heat dissipation,

Which becomes an even greater challenge in hot,

Humid climates.

Hummingbirds dissipate heat partially by evaporation through exhaled air,

And from body structures with thin or no feather covering,

Such as around the eyes,

Shoulders,

Under the wings,

And feet.

While hovering,

Hummingbirds do not benefit from the heat loss by air convection during forward flight,

Except for air movement generated by their rapid wingbeat,

Possibly aiding convection heat loss from the extended feed.

Smaller hummingbird species appear to adapt their relatively higher surface-to-volume ratio to improve convective cooling from air movement by the wings.

When air temperatures rise above 36 degrees Celsius,

Thermal gradients driving heat passively by convective dissipation from around the eyes,

Shoulders,

And feet are reduced or eliminated,

Requiring heat dissipation mainly by evaporation and exhalation.

In cold climates,

Hummingbirds retract their feed into breast feathers to eliminate skin exposure and minimize heat dissipation.

Reviews

Very exciting. Took me in many zooming direction, mainly in the direction of sleep.

Thank you Benjamin! I love hummingbirds! They are amazing, magical creatures. Happy Thanksgiving to you and your family! 💜