Anatomy of a Hummingbird: Brain, Heart, Wings & More

Hummingbirds flying next to beautiful red flower

Iconic for being tiny aerial acrobats, hummingbirds carry a surprising secret despite their small stature: their hearts are remarkably large. But what other mysteries does the hummingbird’s anatomy hold?

In particular, have you thought about how these birds zoom through the air so smoothly? How do their wings handle all that swift movement? Further, what makes their tiny brains so adept at navigating complex environments?

In this article, we will discuss everything there is to know about the anatomy of hummingbirds. We will also include little-known facts regarding their unique physiology and behaviors. Let’s begin!

The Anatomy of Hummingbirds

Weight and Size

Hummingbird weight and size

Generally speaking, hummingbirds exhibit a fascinating range of weights across different species.

To be specific, Bee Hummingbirds are the lightest, weighing between 0.06 and 0.07 ounces. On top of that, they measure approximately 2 to 2.4 inches in length.

Following closely are the Calliope Hummingbird and Costa’s Hummingbird, according to our comprehensive list of the smallest birds in the world.

In contrast, Giant Hummingbirds hold the title for the largest, with a weight ranging from 0.6 to 0.9 ounces. Found along the Andes from Ecuador to Chile, they boast a length of 9.1 inches and a wingspan of 8.5 inches.

Fun Fact: A newborn hummingbird chick’s weight is as little as 0.02 ounces, which is about the same as a paper clip.


Hummingbird head shape and brain

Did you know that hummingbirds have brains that constitute roughly 4.2% of their body weight? That is a higher percentage compared to most other birds, as well as many mammals.

This shows just how smart and advanced these tiny birds are in the avian world.

For one thing, their intelligence is evident in their memory. Hummingbirds remember every flower they visit, including the time it takes for the flowers to replenish their nectar.

Additionally, their brains are wired for high-speed information processing, enabling them to make instant judgments mid-flight. In particular, this rapid decision-making is crucial for evading predators.

Fun Fact: Apart from high intelligence, hummingbirds’ brains are also models of energy efficiency.


Hummingbird beakbill

With a design that’s as functional as it is striking, hummingbird beaks are long, slender, and often curve downwards. This unique shape allows them to dig deep into flowers to sip nectar.

However, note that these birds have a wide range of beak sizes and shapes. Primarily, their bills are tailored to the specific flower they feed on.

Take the Sword-billed Hummingbird, for instance. If you don’t count the tail, its beak is longer than its body. This distinctive feature lets it access nectar from flowers with deeply set corollas.

Another interesting aspect is the flexibility of the hummingbirds’ lower jaw, which enables them to widen and capture insects mid-air.

Fun Fact: Recent studies have revealed that hummingbird beaks are more sensitive than once thought, possibly allowing them to sense changes in nectar.


Hummingbird tongue

A hummingbird’s tongue isn’t like the typical bird’s tongue. It’s forked and tubular, acting like a pair of miniature straws.

Relative to their body, the tongues of hummingbirds are surprisingly long. As a matter of fact, their tongues are capable of stretching well beyond the bill; they can even extend up to 1.6 inches.

On another note, a hummingbird’s tongue can move in and out of its beak up to 18 times per second during feeding. This rapid motion allows them to consume nectar from numerous flowers quickly.

Fun Fact: Fascinatingly, their long tongue actually coils up inside their head when they’re not using it. To be exact, it wraps around their skull and eyes.

Check out this video to learn more about hummingbird tongues:

How the Hummingbird Wields Its Snake-Like Tongue | ScienceTake


Hummingbird bones

As tiny as they may seem, hummingbirds possess a high bone count relative to their size. However, their bones are designed for minimal weight; they are thin and hollow.

Uniquely, hummingbirds also have eight sets of ribs, unlike the six found in most other birds. Plus, their elbow and wrist bones are merged. These adaptations provide structural support while minimizing weight.

Fun Fact: Hummingbirds are special because they don’t have some of the bones other avians do, like the alula for flight control. This absence helps keep them lightweight and streamlined, making their flight super efficient.


Hummingbird cloaca

The cloaca in hummingbirds serves multiple vital functions. Specifically, it acts as the single exit for digestive, urinary, and reproductive systems.

During mating season, both male and female hummingbirds experience cloacal swelling, enabling the transfer of sperm through a brief contact known as a “cloacal kiss.”

Additionally, these birds frequently produce waste due to their fast metabolism and continuous nectar consumption. The cloaca then facilitates quick elimination, which reduces their exposure to predators.

Fun Fact: The hummingbird’s cloaca also aids in thermoregulation. It helps these birds release excess heat through waste.


Hummingbird crop

The crop is an essential feature in the anatomy of a hummingbird, as it serves as a storage unit within the esophagus. Basically, it allows these birds to collect and hold nectar.

In terms of quantity, hummingbirds usually fill their crop about 1/10 to 1/3 full while feeding. But those that face more competition tend to fill up even more when they get the chance.

Fun Fact: A cool aspect of an adult hummingbird’s crop is its role in nurturing baby hummingbirds. These avians can regurgitate partly digested bugs and nectar stored in their crop to feed their little ones.


Hummingbird duodenum

While hummingbirds love nectar, their duodenum is crucial for providing more than just a rapid energy boost. It is a specialized loop around the pancreas, which is important for digesting nutrients from insects.

The duodenum secretes enzymes necessary for breaking down the proteins, fats, and carbohydrates in their prey.

Fun Fact: Mostly, hummingbirds enjoy snacking on ants, aphids, fruit flies, gnats, weevils, beetles, mites, and mosquitoes.


Hummingbird ears

Hummingbirds have a simple ear setup: an outer opening leading to the eardrum without external ear flaps. Positioned on each side of their head, this helps them hear sounds from all directions while flying.

Fun Fact: Interestingly, hummingbirds are surrounded by high-frequency sounds, including those from their rapid wing beats exceeding 80 Hz. But they’re masters at tuning out all that noise to focus on spotting predators.


Hummingbird erythrocytes

Commonly known as red blood cells, erythrocytes are critical for hummingbirds because they carry oxygen all over these avians’ small bodies. This function is vital for sustaining their high-energy lifestyle.

Fun Fact: Hummingbirds have an incredible number of red blood cells, possibly more than 6.5 million cells per microliter! This helps them zip, hover, and zoom around with excellent agility.


Hummingbird esophagus

The esophagus in hummingbirds serves as a flexible tube that links the throat and crop to the stomach. Its remarkable elasticity allows these birds to consume large quantities of nectar and small insects.

Fun Fact: It only takes about four minutes for a hummingbird’s esophagus to transfer half of the nectar it drinks to its stomach and intestines. That’s a quick refuel, which gets these avians back into flight in no time.


Hummingbird eyelids

As with most birds, hummingbirds are equipped with three sets of eyelids: upper, lower, and a special nictitating membrane.

This third eyelid helps keep their eyes safe and moist while they fly, acting like built-in goggles as they swiftly move among flowers or soar through the air.

Fun Fact: Some hummingbird species have eyelids that match the color of their feathers. Besides protecting their eyes, this lovely trait might help with communication or even make them more attractive during mating rituals.


Hummingbird eyes

Thanks to their eyes’ positioning and spherical shape, hummingbirds boast a 360-degree field of vision. This wide-ranging sight is essential for detecting predators and navigating cluttered environments.

Fun Fact: These birds can see ultraviolet light. Basically, this unusual ability lets them see a wider range of colors, making it easier for them to spot the flowers they need to feed on.

Tail and Wing Feathers

Hummingbird tail and wing feathers

Hummingbird wings are meticulously organized into primary and secondary feathers, known as remiges. Each wing hosts ten primary feathers, labeled R1 to R10, which are crucial for flight dynamics.

Similarly, their tails consist of ten feathers, or rectrices, split equally on each side and numbered R1 to R5. These feathers aid in steering and stability during flight, playing a pivotal part in their aerial agility.

However, be aware that not all hummingbirds share the same tail structure.

During a trip to Ecuador, I got to watch awesome hummingbirds in their natural habitats. One of them, the Booted Racket-tail, caught my eye with its cool tail feathers shaped like tiny rackets.

In contrast, while exploring the forests of Peru, I encountered the Marvelous Spatuletail. This species fascinated me with its spatula-shaped outer tail feathers.


Hummingbird feet

As surprising as it may seem, hummingbirds possess anisodactyl feet. This means they have three toes facing forward and one facing backward.

Such a structure is ideal for clinging onto branches and perches, ensuring they remain stable while resting or sleeping.

Fun Fact: Female hummingbirds exhibit exceptional skill with their feet when building nests. They expertly use their toes to gather and weave together materials like spider webs and plant fibers.

Female Reproductive System

Female hummingbird

In hummingbirds, females are notable among many bird species for having just one functional ovary, which is the left one.

This adaptation does not hinder their reproductive capabilities, though. Instead, it streamlines their body for the high-energy demands of flight.

Despite this single ovary setup, female hummingbirds are quite prolific, laying 1 to 3 eggs per breeding cycle. These eggs are relatively large for the bird’s size, which is comparable to a jellybean or pea.

Male Reproductive System

Male hummingbird

Male hummingbirds undergo a fascinating transformation during the breeding season, where their testes expand dramatically to produce sperm. This increase can be as much as 100 times their off-season size.

This adaptation allows male hummingbirds to focus on flying efficiency and foraging outside the breeding season by minimizing excess weight.

Fun Fact: Have you ever heard of the Great-billed Hermit? It turns out that these hummingbirds have three testes, which is a condition called triorchidism.


Hummingbird anatomy diagram

Even though it is tiny, the gizzard is very important for a hummingbird’s digestion. It is a muscular organ that grinds up hard food particles, such as insect shells.


Hummingbird gorget

The gorget in male hummingbirds is a striking, bright-colored patch on their throat, named after the protective throat armor of knights. But this vibrant detail isn’t just for looks; it is crucial in their courtship dances.

During courting, males skillfully position themselves to catch the sunlight on their gorget, setting it ablaze with color. This is often paired with elaborate flight patterns designed to impress and attract potential mates.


Hummingbird heart

Hummingbirds boast the largest heart relative to body size in the animal kingdom, which comprises around 2.5% of their weight.

This powerful organ supports their energetic lifestyle, pumping blood efficiently to meet high metabolic demands.

Specifically, their heart rate can skyrocket to 1,260 beats per minute during vigorous activity. In fact, even at rest, their heart beats at an impressive rate of up to 250 times per minute.

When it’s night, though, hummingbirds enter a torpor state to conserve energy. During this time, their heart rate slows down dramatically, sometimes reaching only 50 to 180 beats per minute.


Hummingbird kidneys

While hummingbirds are tiny, their kidneys are packed with thousands of nephrons. These kidneys work hard to keep these birds’ blood clean by getting rid of waste products.

Fun Fact: Hummingbirds can actually take a break from their kidney function at night. It is a neat trick that helps them conserve energy and water, which is critical for their survival.


Hummingbird legs

Broadly speaking, hummingbirds are equipped with incredibly small and light legs. But note that these aren’t meant for walking or hopping as seen in other bird species.

Their legs are mainly adapted for perching, supporting their lifestyle that requires constant hovering and flying.

Fun Fact: Though their legs aren’t primarily used for grooming, hummingbirds occasionally utilize their feet to help clean their feathers. They adeptly use them to remove debris or parasites.


Hummingbird liver

Unmatched in nature, hummingbirds have highly active livers that can efficiently burn glucose and fructose equally. This capability allows them to maintain energy levels without converting sugar into fat.

Additionally, their livers have a vital role in detoxification; they clear toxins from the body. This function is essential for ensuring they maximize their lifespan, which typically falls between 3 and 5 years.


Hummingbird lungs diagram

The hummingbird’s respiratory efficiency is attributed to its advanced system, which features two lungs and nine air sacs.

While at rest, a hummingbird takes around 300 breaths per minute, which is a number that can escalate to 500 breaths per minute during active flight.

Lymphatic System

Hummingbird lymphatic system

Just like all birds, hummingbirds boast a tidy lymphatic setup featuring the thymus gland, lymphatic circulation, and the bursa of Fabricius.

Primarily, this system is tasked with removing waste and combating infections, ensuring that hummingbirds can continue their high-energy activities without surrendering to disease.

Neck Vertebrae

Hummingbird neck vertebrae

Hummingbirds are provided with 14 to 15 neck vertebrae, which surpass that of many other bird species. With this, it is unsurprising to learn that they can twist and turn to reach deep into flowers while feeding.

In short, this flexibility helps them get nectar from all sorts of flower shapes.


Hummingbird nostrils

Acting as their main air intake point, note that hummingbird nostrils are strategically positioned at the base of these birds’ beaks.

Fun Fact: Hummingbirds rely on their sense of smell to stay safe. They are clever at steering clear of pesky bugs while they search for sweet nectar.

Pectoralis and Supracoracoideus Muscles

Hummingbird pectoralis and supracoracoideus muscles

The pectoralis muscle makes up around 25 to 30% of a hummingbird’s total body weight. This muscle is key for the downward stroke of the wings. Simply put, it provides the thrust needed for aerial acrobatics.

Beneath the pectoralis lies the supracoracoideus muscle, which is smaller but essential for lifting the wing after each downstroke.

Fun Fact: These muscles also enable the wings of hummingbirds to rotate 180 degrees in all directions.

Small Intestine

Hummingbird small intestine

Hummingbirds’ tiny tummies do big work in their small intestines. This particular spot is like a VIP lounge for their sugary treats, as it is packed with very efficient transporters that absorb simple sugars.


Hummingbird sternum

Serving as their flight powerhouse, hummingbirds boast a distinctive sternum with a prominent keel. To be exact, this is where their necessary pectoral muscles clamp.

But despite its robustness for muscle attachment, these birds’ sternum maintains flexibility. It supports their wings’ extensive range of movement, such as hovering and sideways flying.

Body Temperature

Hummingbird in cold temperature

During their active hours, hummingbirds maintain a body temperature between 104°F and 108°F. This high temperature supports their rapid metabolism and intense energy demands.

In states of torpor, however, their body temperature can drop significantly to conserve energy. A shallow torpor sees a reduction of about 20°F. Meanwhile, during deep torpor, the temp can decrease by up to 50°F.

But did you know that on chilly mornings, hummingbirds can often be seen sunbathing to raise their body warmth?

On a cool morning hike, I observed a group of hummingbirds engaging in what appeared to be a sunbathing ritual. They perched on branches that received direct sunlight, strategically positioning themselves to catch the rays.

As I later learned, this helps hummingbirds warm up their bodies. The sun’s heat prepares them for a day of dynamic flying, feeding, and territorial defense.


Hummingbird ureters

In hummingbirds, every feature is designed for lightness, including their ureters. These slender tubes play a critical function without adding unnecessary weight.

In particular, they are responsible for transporting waste from the kidneys for elimination.

Uropygial Gland

Hummingbird uropygial gland

Located near the base of their tail, the uropygial gland in hummingbirds produces an oil crucial for feather maintenance.

During preening, hummingbirds spread this oil across their feathers, ensuring they remain supple, waterproof, and well-conditioned.


Hummingbird wings

Hummingbirds have the ability to beat their wings up to 80 times per second during normal flight, and this frequency can skyrocket to 200 times per second in a courtship dive.

Fun Fact: Contrary to flapping, these birds rotate their wings in an unusual figure-eight motion. This allows for impressive maneuvers such as flying backward and hovering in place.


Hummingbird metabolism

In general, hummingbirds hold the record for the highest metabolism among all homeothermic animals.

So, to sustain this metabolic rate, these avians consume about their body weight in nectar and insects daily. For a human, this would be equivalent to eating 155,000 calories a day.

Fun Fact: Before migration, hummingbirds double their fat mass to store energy for long journeys without food. This preparation allows them to travel hundreds or thousands of miles.

Hummingbird Anatomy FAQs

Hummingbird side profile

Can Hummingbirds Open Their Beaks?

Yes, hummingbirds can open their beaks. This might surprise some, as their beaks often appear tightly shut, especially when they’re hovering around feeders. However, this slight opening is crucial for their feeding method.

To be specific, their beaks part just enough to allow their tongues to dart in and out rapidly. This action enables them to lap up sugar water from feeders or the nectar from flowers.

How Far Can a Hummingbird Stick Out Its Tongue?

A hummingbird’s tongue can extend an impressive distance, reaching up to 1.6 inches. This length allows them to access nectar deep within flowers that other birds can’t reach.

But after feeding, hummingbirds have an unusual way of retracting their tongues. Instead of simply pulling it back, their tongue coils up inside their head. Basically, this coiling action wraps the tongue around their skull.

What Is the Blood Pressure of a Hummingbird?

Hummingbirds have a surprisingly high blood pressure, with readings between 108 and 250 mmHg. This range is essential for supporting their rapid and energetic lifestyle.

Their cardiovascular system is adapted to this high demand through a high stroke volume and fast heart rate, which can be 150 to 350 beats per minute. Additionally, they possess stiffer arteries compared to other birds.

Do Hummingbirds Have Teeth?

Like all birds, hummingbirds do not have teeth in the traditional sense. Their beaks are designed for precision in accessing nectar, not for chewing food.

Some species of hummingbirds, however, do feature tiny serrations along their beak’s edge, known as tomial serrations. These “teeth” play a crucial role in their feeding by helping to clean their tongue ends.

Moreover, their tomial serrations serve as a weapon in territorial disputes and fights with other hummingbirds.

How Can Hummingbirds Hover in Mid-Air?

Hummingbirds can hover in mid-air by flapping their wings more than 80 times per second. This incredible speed is necessary to keep them suspended in place, requiring their wings to be in constant motion.

Strong flight muscles and flexible shoulder joints also support their ability to hover. In addition, their crescent-shaped wings and high wing loading aid in creating the lift needed for them to hover.

Can Hummingbirds See Colors?

Hummingbirds possess an exceptional ability to see colors far beyond the human spectrum. Attracted not only to red, they also favor flowers in shades of orange, pink, and yellow.

However, their color preference doesn’t stop there; they are known to feed from flowers of various other tints, demonstrating their broad visual palette.

Interestingly, a 2020 study involving over 6,000 feeder visits across 19 experiments shed light on their unique color vision. It was discovered that hummingbirds can see various non-spectral hues as well.

Hopefully, this guide has helped you in understanding the hummingbird’s anatomy. What are your thoughts or questions on these awesome creatures? Feel free to share them with us in the comments below!

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