Hummingbirds are unique among birds for their ability to hover in mid-air and fly backwards, sideways, and upside down with precision and agility. So do hummingbirds truly fly, or do they simply hover? The answer is that hummingbirds actually do both.
What is the difference between flying and hovering?
Flying refers to the forward motion of a bird through the air over long distances. It requires generating enough lift and thrust to overcome gravity and air resistance in order to propel forward. Birds fly by flapping their wings to generate lift and thrust. The air flows faster over the top of the wing than the bottom, creating an area of lower pressure above the wing relative to the higher pressure below it. This pressure difference produces an upward lifting force. At the same time, the backward motion of the flapping wings generates thrust to overcome drag and push the bird forward.
Hovering, on the other hand, refers to staying suspended in one place while rapidly moving the wings to stay aloft. The wings still provide lift to oppose gravity, but there is zero horizontal motion so no thrust is required. Only enough airflow over the wings is generated to balance the bird’s weight. Hummingbirds, bees, and certain other flying creatures are capable of true hovering.
How do hummingbirds fly?
During normal flight, hummingbirds support their weight and propel themselves forward by rapidly flapping their wings in a figure-eight pattern. On the downstroke, the wings generate lift and thrust, while on the upstroke they are folded in to minimize negative lift. A hummingbird’s wings can beat up to 200 times per second, the highest known rate of any vertebrate animal. This allows them to generate the requisite lift and thrust to fly.
Key facts about hummingbird flight:
- Wings beat in a figure-eight pattern
- Up to 200 flaps per second
- Wings angled to maximize lift on downstroke
- Wings folded in to reduce negative lift on upstroke
- Enough lift generated to oppose body weight
- Forward thrust generated to overcome drag
This rapid wing movement allows hummingbirds to fly forwards, backwards, up, down, and hover in place. The wings provide enough variable lift and thrust to control their flight precisely in any direction.
How do hummingbirds hover?
Hummingbirds have the specialized ability to hover in mid-air by rapidly beating their wings in a nearly horizontal plane. While hovering, their wings rotate in a figure-eight pattern and generate enough lift to keep them suspended against gravity. Here is how it works:
- Wings beat at 40-80 flaps per second, varying species to species
- Aerodynamically angled to provide maximum lift
- Only slight tilt to the stroke plane provides some asymmetry in lift
- Wings still flip over at end of each stroke
- The downstroke provides lift and the upstroke provides very little
- Wings articulate at shoulder to optimize angle of attack
This horizontal flapping motion generates enough lift to equal the bird’s weight, keeping it hovering. The rapid wing movement also produces a cushion of air on which the hummingbird sits. There is no forward motion, only upward and downward force. Some unique adaptations enable this specialized hover flight:
- Lightweight – hummingbird bodies and bones are compact and lightweight
- Enlarged chest muscles for powering wings, making up 25-30% of their weight
- Rotating shoulders allow wings to move in optimal planes
- Large wing surface relative to their weight provides more lift
Hummingbirds can rapidly transition from forward flight to a stationary hover by altering the angle of their wingbeats and adjusting the axis of rotation. They have incredible control over their flying motions.
When do hummingbirds hover vs fly?
Hummingbirds use both flying and hovering flight to meet different needs:
Type of Flight | When Used |
---|---|
Forward flight |
|
Hovering |
|
Hummingbirds spend the majority of their time during the day hovering as they feed on flower nectar. However, they utilize efficient forward flight for traveling longer distances such as seasonal migration across continents. The physics of hovering makes it an extremely energy-intensive activity. Hummingbirds have adaptations to meet these energy demands:
- High metabolism and heart rate
- Ability to metabolize sugars for energy quickly
- Feeding frequently throughout the day
- Entering torpor-like states at night to conserve energy
Unique characteristics of hummingbird flight and hover
Hummingbirds stand out from other birds because of these exceptional flight abilities:
- Backwards flight – Can maneuver backwards by altering the angle of their wings
- Sideways flight – Can fly sideways by changing the plane of wing movement
- Upside-down hover – Can invert their hover to feed upside-down
- Light flap glide – Use an energy-saving flap-glide method for migrations
- Fast acceleration – Rapidly accelerate by clapping wings together above their backs
- Precise maneuverability – Extreme agility in flight due to small size
- Hover stability – Minute adjustments maintain stable hover position
This advanced flight mastery allows hummingbirds to thrive in their environments. The characteristic humming sound is produced by specialized wing feather adaptations that maximize lift on the downstroke.
Do other birds hover?
While hummingbirds are the masters of sustained hovering, some other birds can hover briefly, including:
- Kestrels
- Kingfishers
- Nighthawks
- Terns
- Hawks
These birds use a burst of fast flapping to generate enough lift to hover for a few seconds, such as when spying or capturing prey. True sustained hovering is a uniquely hummingbird trait among birds. Insects like bees and dragonflies are also capable hoverers.
Why do hummingbirds hover?
Hummingbirds’ ability to sustain a stationary hover in mid-air is an adaptation that allows them to feed on flower nectar. Reasons hummingbirds hover include:
- Access flower nectar while remaining stationary in front of the flower
- Precisely maintain position to feed despite wind or movement
- Quickly redirect to another flower or food source
- Conserve energy when feeding for long periods
- Feed from a variety of flower shapes and orientations
- Switch directions to follow food sources
- Contend with other hummingbirds at feeders
Hovering enables hummingbirds to feed while minimizing energy expenditure. It allows great precision and control in accessing food sources. Hummingbirds’ adaptations for hovering likely evolved due to the energy benefits it provides in accessing scattered, ephemeral flower nectar.
How much do hummingbirds hover vs fly?
Hummingbirds actually spend more time hovering than flying. Here is an approximate breakdown:
- Time spent hovering – 75%
- Time spent perching – 10%
- Time spent flying – 15%
The vast majority of a hummingbird’s active day is spent sustainably hovering as they feed on flower nectar, sap, and insects. Their feeding strategy is optimized by their ability to remain hovering in an energy-efficient manner at each food source. Hovering constitutes the majority of their flight time.
However, hummingbirds do utilize more metabolically-costly forward flight when migrating, defending territory, breeding, and traveling. Their flight abilities allow them to meet the demands of both hovering and powered forward flight.
Conclusion
In conclusion, hummingbirds truly master both sustained hovering and forward flight. Their rapid wing-flapping enables them to hover with great stability as they feed, yet also fly over long distances during migration. While hovering, they generate enough lift to suspend themselves motionlessly in front of flowers and food sources. When flying forward, they flap their wings in a figure-eight motion to provide lift and thrust. Hummingbirds can quickly transition between these flight modes using specialized adaptations like rotated arm joints and enlarged muscle mass. So next time you see a hummingbird effortlessly hovering in one spot, remember it is an elegant example of their unique hovering and flight capabilities.