Hummingbirds are known for the distinct humming sound created by their rapidly beating wings. Their wings can flap up to 80 times per second, producing a persistent humming noise as the birds hover at flowers to feed on nectar. Thisbehavior gave rise to the name “hummingbird.”
The Origins of the Name Hummingbird
The first recorded use of the word “hummingbird” dates back to the early 1600s. English settlers arriving in America encountered these tiny, brightly colored birds for the first time and were struck by the constant buzzing sound of their wings. The humming noise emanating from their rapid wingbeats was reminiscent of the hum of a bee, so early observers referred to the birds as “humming bees” or “humming wasps.” Over time, this was shortened to “hummingbird.”
The earliest published use of the word “hummingbird” appears in the travel memoirs of explorer William Strachey, who documented his time at the Jamestown colony in Virginia between 1610 and 1611. He described “humming birds” as “one kind of small birds, which I took to be humnius birds.” The comparison to bees and wasps also led to some early confusion over whether hummingbirds were insects or avians.
The term “hummingbird” stuck once it was clear they were birds. The word first appeared in a 1635 English dictionary which defined hummingbird as “a Bird called the humming Bird from the sound it makes with its wings.” Their specific tendency to hover at flowers while feeding, accompanied by the signature hum of their wings, solidified “hummingbird” as an apt and descriptive name.
Unique Anatomy Allows Hummingbirds to Hum
Hummingbirds have specialized anatomy that enables them to beat their wings up to 80 times per second. Key adaptations include:
- Lightweight skeleton and small size
- Wings that can rotate in a full circle
- Enhanced muscle mass relative to their weight
- A larger portion of their brain dedicated to coordination
Weighing just 2-20 grams on average, hummingbirds have incredibly light skeletons with hollow, fragile bones. Their small size and limited weight enable their wings to flap at high frequencies without overtaxing their bodies. Hummingbird wings are capable of rotating in a full circle as well as moving up and down. Most birds can only flap their wings open and closed.
Up to one third of a hummingbird’s total muscle mass is in their chest, powering each wingbeat. They can also utilize newly consumed sugars to fuel their muscles mid-flight by converting nectar into energy more quickly than most animals.
All of this takes remarkable coordination. Up to 30% of a hummingbird’s neurons are in the cerebellum region of its brain which controls motor function and coordination. This allows their brains to precisely direct rapid wing movements.
Wing Anatomy Maximizes Hovering Flight
Hummingbird wings are specially designed to enable both forward flight and precise hovering:
- Their bones form a flattened, aerodynamic shape
- The forward edge of their wings are stiff while the rear edge is flexible
- They can angle their wings into a V-shape while hovering
Viewed from below, their wings are narrow at the tip and wider at the base where they join the body, creating an ideal airfoil shape that minimizes drag. The rigid forward section of each wing leads the stroke, while the flexible rear feathers fan out to maximize lift.
By adjustably altering the angle of their wings mid-stroke into a V-shape, they can produce the lift needed to hover in place while feeding. When flying forward, they straighten their wings into more of a U-shape for propulsion.
Wing Muscles Account for One-Third of Their Weight
A hummingbird’s wing muscles make up a sizable percentage of their overall body weight:
Species | Wing Muscles as % of Weight |
---|---|
ruby-throated hummingbird | 25-30% |
Rufous hummingbird | 27-34% |
blue-throated hummingbird | 21-26% |
Anna’s hummingbird | 34-40% |
For comparison, wing muscles make up just 12-15% of total weight in similarly sized insects and under 20% in most birds. The proportionately larger pectoral muscles of hummingbirds allow them to produce the force needed to beat their wings over 70 times per second.
Wingbeat Frequency Varies by Species
Different hummingbird species have wings tailored to their specific needs, which produces variation in wingbeat frequency. Here are average wingbeat rates for selected species during hovering:
Species | Wingbeat Rate (beats/sec) |
---|---|
bee hummingbird | 200 |
calliope hummingbird | 80 |
rufous hummingbird | 55 |
ruby-throated hummingbird | 53 |
broad-tailed hummingbird | 48 |
black-chinned hummingbird | 43 |
The bee hummingbird, smallest in the world, can beat its wings up to 200 times per second. Larger species like the rufous and ruby-throated hummingbird generally flap around 50 times per second. This demonstrates the link between size and wing speed.
Sexual Dimorphism
Within a species, male hummingbirds tend to have faster wingbeat frequencies than females. This is linked to sexual dimorphism – physical differences between the sexes. Males evolve elaborate colors and airborne courtship displays, so their wings become more specialized for agility and speed.
Altitude Adaptations
Hummingbirds native to higher altitudes also tend to have faster wingbeats, likely an adaptation to thinner air. For example, the Andean emerald hummingbird beats its wings 85 times per second compared to 50 beats for its lowland cousin, the blue-throated hummingbird.
Metabolic Rate
Faster wingbeats require more energy, so hummingbirds with quicker wing movements tend to have higher metabolic rates. Their hearts can reach up to 1260 beats per minute while foraging.
Hovering Flight is Extremely Energy Intensive
The act of hovering takes immense exertion. The metabolic rate of rufous hummingbirds while simply perching is 12 watts. During hovering flight, their metabolism skyrockets to 60-70 watts as they burn calories at up to ten times their resting rate.
Maintaining precise hover positioning leaves no room for error. Any slight deviation will cause them to rapidly drop out of suspension. This is why hummingbirds rarely hover for more than a few seconds at a time, relying on small burst movements to maintain stability.
Energy Strategies
To meet their extreme energy needs, hummingbirds have adapted specialized behavioral and physiological strategies:
- They gorge on high-sugar nectar to fuel their metabolism
- They enter a hibernation-like state when food is scarce to conserve energy
- They selectively slow their heart rate while resting
- They absorb and process sugars rapidly to utilize food energy immediately
These evolutionary mechanisms help hummingbirds energetically sustain their unique hovering ability and rapid wingbeats.
Aerodynamic Hovering is Essential to Feeding
Hummingbirds’ capacity for sustained hovering flight is vital to their survival. As nectar-feeding specialists, they heavily rely on suspended airborne positioning to forage:
- Hovering allows them to maintain access to flower nectar as they lick it up with their long tongues
- It enables them to precisely maintain their position relative to a food source
- Suspended flight lets them probe flowers not well-suited to perching
This distinctive hovering behavior, accompanied by the tell-tale hum of their wings, helped establish “hummingbird” as an apt descriptive term.
The Sound is Used for Courtship Displays
The humming noise produced by wings plays a role in hummingbird courtship. Males perform aerial shows for females where they dive and climb repeatedly at rapid speeds, creating sounds from their wingbeats and tail feathers.
Studies on Anna’s hummingbirds found males peak their dive speeds at around 385 body lengths per second, producing a loud chirp or whistle. This noise likely evolved to impress females. The better a suitor’s dives sound, the stronger his muscle coordination is implied to be.
The sustained humming created during hovering is also thought to help hummingbirds identify and connect with potential mates of the same species.
Hummingbird Wings Inspire Innovations in Wing Design
The unique properties of hummingbird wings have captured the interest of aeronautical engineers hoping to apply their principles to improve human technologies. Areas being studied include:
- Developing robotic hummingbird wings for micro-surveillance drones
- Using hummingbird-inspired wings to improve lift generation in micro-air vehicles
- Adapting their flexible wing dynamics to build more versatile aircraft
- Studying their complex wing joints to improve flying robot maneuverability
While early biomimicry efforts have shown promise, scientists still struggle to fully replicate the intricacy of hummingbird wings. Their flying capabilities continue to teach researchers about aerodynamics, energy efficiency, and principles of flight.
Conclusion
Hummingbirds get their descriptive name from the audible hum caused by rapidly beating wings that let them effortlessly hover and feed on flower nectar. Precise hovering is possible thanks to specialized adaptations like light weight, rotated wrist bones, enlarged muscle mass, and a unique wing structure that maximizes lift. The energy demands of this constant hovering flight led hummingbirds to evolve a highly efficient metabolism and foraging behaviors to stay fueled. While scientists work to fully understand and replicate their complex biological wings, these tiny birds will continue to inspire human innovation with the persistent humming sound that is their namesake.