Hummingbirds are known for the humming sound their wings make as they buzz around from flower to flower. But do they continue making noise while in flight, or do they fly silently between destinations? Here’s a look at what sounds hummingbirds actually make when flying.
The Humming Sound
The most recognizable sound hummingbirds make is the humming or buzzing noise their wings produce as they beat incredibly fast. Hummingbirds have the ability to flap their wings up to 80 times per second, and it’s this rapid oscillation that causes the humming or buzzing sound.
The noise comes from airflow over the wing as the bird alternately pushes down and up. The wings are specially adapted to maximize lift on both the downstroke and upstroke, creating a blur of motion. This allows hummingbirds to hover effortlessly as they feed on nectar from flowers. The resulting sound is a distinctive hum:
| Downstroke | Air pushed below wing to create lift and make humming noise |
|---|---|
| Upstroke | Wings flipped to maintain airflow and lift on upstroke, continuing humming sound |
The frequency of the humming varies by species. The wings of larger hummingbirds like the Giant Hummingbird beat around 12-15 times per second. Smaller species can flap up to 80 times per second. The faster the wings move, the higher the pitch of the hum. This rapid oscillation allows hummingbirds to hover in place as they feed or engage in complex aerial courtship displays.
Sound Only When Hovering
Hummingbirds only produce this characteristic humming sound when they are hovering. During forward flight, the wings are beating at a different angle to produce thrust, so the airflow and resulting noise are different.
Studies using recordings of flying hummingbirds have found the hum is mostly eliminated during horizontal forward flight. Instead, there are reports of occasional buzzing, squeaking, or chirping sounds as air moves over the tail feathers and wings at high speeds.
So while feeding at a flower, the rapid wing motion produces an audible hum. But in transit between flowers, the only sound is the high-pitched squeak of air passing over the streamlined body and wings.
Vocalizations
In addition to wing sounds, hummingbirds can make a surprising variety of vocal calls. Thesebird sounds are used for communication rather than flight:
Chirps and Squeaks
Hummingbirds have thin, squeaky vocalizations used during aggressive encounters over feeders or territory. Both males and females make these mostly inaudible squeaking or clicking sounds during conflicts.
Shrill Chip Notes
Another sharp call is the “chip” note made by males during courtship displays. These single chips serve as a way to get a female’s attention. They are one of the few vocalizations made during a courtship display flight.
Dive Sound
Males also make a metallic “zooming” sound with their tail feathers while diving during the courtship display. This is caused by air moving through the tail feathers and serves to impress watching females.
Song
Some hummingbird species sing actual songs. In the a man like the Anna’s Hummingbird, males have a complex warbling song used during the breeding season to define territories and attract mates. The songs have multiple syllables and last 5-10 seconds, unusual for a bird so small.
| Vocalization Type | Sound Description | Purpose |
|---|---|---|
| Squeaks/Chirps | High-pitched inaudible sounds | Aggressive encounters |
| Chip note | Shrill single chip sound | Get female attention |
| Dive sound | Metallic zooming noise | Impress females |
| Song | Complex warbling song | Attract mate, defend territory |
So while making their signature hum with wings, hummingbirds can also vocalize to communicate, defend territory, and court mates.
No Sound in Slow Motion
High-speed video has provided an interesting look at hummingbird flight and sound. When played back in slow motion, the rapid wing motion that normally creates a hum no longer results in any audible sound.
Without the rapid frequency necessary to produce a humming noise, the wings flap silently back and forth. This demonstrates that the distinctive hum is directly tied to the speed of wing motion during hovering and feeding. In slow motion, there is no longer enough airflow over the wing to create noise.
Why Film Reveals No Sound
There are a few reasons why slow motion hummingbird footage lacks sound:
- Slower wingbeat frequency doesn’t create the airflow needed for humming
- Sound recorded at normal speed drops in pitch when slowed down
- Microphones limited in range of frequencies they can detect
By revealing the absence of sound at slower speeds, high-speed cameras demonstrate that the hum is created by the rapid oscillation of the wings rather than the motion itself.
Wing Adapted for Sound
Hummingbirds have wings uniquely adapted to produce sound while hovering. Here are some of the ways their wings maximize lift and create a hum:
Small Size
The relatively small surface area of hummingbird wings requires moving them faster to create needed lift. This rapid flapping creates the characteristic humming sound.
Rigid Frame
Hummingbird wing bones are fused together into a rigid frame that resists bending and twisting. This allows the entire wing to move as a synchronized unit for efficiency.
Rotation at Shoulder Joint
Wings attach to a flexible shoulder joint that permits rotation as well as up and down motion. This allows the wing to rotate for the optimum angle of attack on both upstroke and downstroke.
Stiff Feathers
Feathers are made stiff by the protein keratin. The lack of flexibility results in the entire wing surface pushing air downward to create the most lift possible.
| Wing Adaptation | Contribution to Lift and Sound |
|---|---|
| Small surface area | Requires faster flapping to hover, creating humming sound |
| Rigid bone frame | Entire wing moves as unit for maximum lift and continuous airflow |
| Rotating shoulder joint | Optimizes wing angle on both upstroke and downstroke |
| Stiff feathers | No flexibility allows entire wing to push air downward |
In combination, these adaptations allow hummingbird wings to create a sustained hover and a consistent humming sound while feeding.
Absence of Sounds
While hummingbird wings can produce sound, there are also notable absences of sound related to their flight:
Lack of Fluttering
Despite moving at incredible speeds, hummingbird wings do not create the fluttering sounds of other birds. The rigid bone and feather structure moves as one smooth unit without fluttering.
No Sound at Low Speeds
As seen on slow motion video, the rapid oscillations required to hover are needed to create humming sounds. At slower speeds, their wing motion is silent.
Quiet Flight Between Flowers
During forward flight, there is no humming sound. Only the occasional faint squeak is heard as air moves over the body and tail.
Silent Perching
When hummingbirds perch to rest between meals, they are silent. Their small size means they don’t need to vocalize like songbirds.
So while the wings can create noise, hummingbirds have also evolved for silent flight when needed. This allows them to move efficiently and stealthily between food sources.
Specialized Structure of Feathers
Hummingbird feathers have specialized structures that aid in sound production:
Stiff Shaft
The shaft running up the center of the feather is made rigid by keratin. This allows the entire feather to move as one unit without bending.
Interlocked Barbs
Tiny structures called barbules on each side of the feather shaft interlock with the adjacent feather. This creates a continuous wing surface to maximize airflow and lift.
Asymmetrical Vanes
The vanes on each side of the feather shaft are uneven in width. This alters airflow and lift characteristics to optimize wing performance.
| Feather Structure | Contribution to Wing Motion and Sound |
|---|---|
| Stiff central shaft | Entire feather moves as unit without bending |
| Interlocked barbules | Creates continuous wing surface |
| Asymmetrical vanes | Optimizes airflow over wing |
The unique engineering of hummingbird feathers allows their wings to move with precision and produce the necessary lift for hovering flight and consistent humming sounds.
Sound Differs by Species
The over 300 species of hummingbirds worldwide create differing sounds with their wings depending on size, wing shape, and flapping frequency. Here are some examples:
Smaller = Higher Frequency
The Bee Hummingbird is the smallest species at just 2 inches long. Its tiny wings beat up to 200 times per second, creating a high-pitched hum.
Larger = Lower Frequency
On the large end, the 7-inch Giant Hummingbird has slower flapping wings that produce a deeper, lower-frequency hum.
Wing Shapes Vary
Long, pointed wingtips and short, rounded wings produce subtle variations in tonal quality of the hum even among same-sized birds.
Males and Females Differ
In some species like Anna’s Hummingbird, males have a faster wingbeat frequency and higher-pitch hum than females. This helps differentiate the sexes.
The range of wing sizes, shapes, and flap rates results in species-specific variations in humming sounds. Next time you hear a hum, see if you can distinguish unique tones.
Measuring Frequency
Scientists use specialized equipment to study the sounds made by hummingbird wings:
High Speed Video
Films and videos made at up to 10,000 frames per second can slow down motion to observe detailed wing movement and airflow to understand how humming is produced.
Microphones
Specialized microphones are placed near hovering hummingbirds to record wing sounds. High frequency and range are required to capture the full spectrum.
Sound Spectrographs
Recordings are analyzed on sound spectrographs. This graphs sound frequencies allowing scientists to visualize unique acoustic signatures of each species.
Wind Tunnels
Wing feathers are studied in wind tunnels reproducing slow to fast airflow. This isolates the types of motion and airflow to understand how lift force is generated.
| Research Method | Information Provided |
|---|---|
| High speed video | Views airflow and wing motion in detail |
| Specialized microphones | Detect full range of hummingbird frequencies |
| Sound spectrographs | Visualize and analyze acoustic signatures |
| Wind tunnels | Observe airflow over wings of different shapes/speeds |
By combining observational and experimental methods, scientists can unlock the secrets of hummingbird wing aerodynamics and sound production.
Summary: The Science of Hummingbird Wing Sounds
Here are the key points on hummingbird wing aerodynamics and the resulting sounds:
- The fast beating of wings creates a hum while hovering and feeding.
- During forward flight there is minimal sound beyond faint squeaks.
- Specialized bone and feather adaptations maximize lift and wing movement.
- Different species create unique sounds based on size, wing shape and flap rate.
- High speed filming shows the noise only happens at fast speeds needed for hovering.
- Advanced tools allow detailed study of wing motion and resulting airflow and acoustics.
The next time you hear the familiar hum of a hovering hummingbird, listen more closely and appreciate the finely tuned instrument that is a hummingbird wing!
