A hummingbird is a very small bird that can hover in mid-air by rapidly flapping its wings 12-80 times per second. Their size and weight varies by species, but they typically weigh between 2-20 grams. A U.S. penny weighs around 2.5 grams. So most hummingbird species are actually lighter than a penny, though some of the larger ones may weigh slightly more.
Comparing Hummingbird Weights
There are over 300 different species of hummingbirds, found exclusively in the Americas. Here are some examples of hummingbird weights:
Hummingbird Species | Weight |
---|---|
Bee Hummingbird | 2 grams |
Calliope Hummingbird | 3 grams |
Rufous Hummingbird | 3-3.5 grams |
Broad-tailed Hummingbird | 4-6 grams |
Blue-throated Hummingbird | 7-9 grams |
Giant Hummingbird | 18-24 grams |
As you can see, most hummingbird species weigh less than a U.S. penny, which is 2.5 grams. The Bee Hummingbird is the smallest at just 2 grams. However, larger species like the Giant Hummingbird can weigh up to 24 grams, making them heavier than a penny. The average hummingbird is probably around 4-6 grams.
Penny Specifications
Since we are comparing the weight of hummingbirds to U.S. pennies, let’s look at the specifications of a penny:
U.S. Penny Facts |
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Diameter: 19.05 mm |
Thickness: 1.52 mm |
Mass: 2.5 grams |
Composition: 97.5% zinc, 2.5% copper |
Pennies were pure copper until 1982, when the composition was changed to the current zinc/copper mixture. The mass has remained consistent at 2.5 grams over time.
Density Comparison
One way to compare the mass of very small objects is to look at their density. Density is calculated by dividing an object’s mass by its volume. Hummingbirds have an average density around 0.9 g/cm3. The density of a penny is about 7.0 g/cm3.
This shows that pennies are much more dense than hummingbirds. A penny is able to pack a lot more mass into a small volume. Even though some hummingbirds may exceed 2.5 grams, most are less dense than a penny of the same weight. The high density of pennies contributes to their small size and heavy weight.
Force of Gravity
Gravity exerts a downward force on all objects proportional to their mass. The Earth’s gravity pulls more strongly on a penny than a hummingbird. We can calculate the force of gravity using the formula:
Force = Mass x Gravity
The acceleration due to gravity on Earth is 9.8 m/s2.
For a 2.5 gram penny:
Force = 0.0025 kg x 9.8 m/s2 = 0.0245 Newtons
For a 5 gram hummingbird:
Force = 0.005 kg x 9.8 m/s2 = 0.049 Newtons
So the force of gravity on a hummingbird is about twice as much as on a penny. But a hummingbird can generate enough lift force to overcome gravity and hover.
How Hummingbirds Hover Despite Gravity
Hummingbirds are able to hover by generating lift with their wings. As they flap, the wings are angled to push air downwards. This creates an upward reaction force called lift that opposes gravity.
Some unique adaptations give hummingbirds the ability to generate high lift:
- Wing anatomy – Hummingbird wings are shaped to provide maximum lift.
- Rapid flapping – Flapping up to 80 times per second allows near-continuous lift production.
- Hovering muscles – Proportionately larger pectoral muscles power the energetic hovering motions.
- Low weight – Their small size and lightweight bones reduce the gravity forces.
During the downstroke, the wings generate up to 3 times the hummingbird’s weight in lift. This enables them to hover effortlessly, despite the downward pull of gravity. No matter the mass of the hummingbird, this unique flying ability lets them overpower gravity.
Lift-to-Weight Ratios
Aerodynamic lift capability is often expressed as a ratio of lift force to weight, called the lift-to-weight ratio. Greater lift allows more ability to overcome gravity.
Typical lift-to-weight ratios:
Object | Lift-to-Weight Ratio |
---|---|
Hummingbird | 1.0 to 3.0 |
Helicopter | 3.5 to 5.0 |
Penny | 0 |
The lift-to-weight ratio of 1.0 to 3.0 enables hummingbirds to hover, fly upwards, or glide down slowly. In contrast, a penny has no ability to generate lift. So while a penny may weigh slightly less than a larger hummingbird, the hummingbird can easily lift off and fly.
Slow Motion Hummingbird Hovering
High speed videos reveal how hummingbirds stay suspended while feeding on flower nectar. Here are some slow motion insights:
- Wings beat around 50 times per second, supporting the bird’s weight.
- The upstroke elevation provides some lift, in addition to the main downstroke.
- At the bottom of each stroke, the wings are inverted to maximize lift.
- The tail may spread to enhance stability and control.
- Rapid adjustments keep the hummingbird precisely balanced in one spot.
This slow motion view shows how wing position, angle of attack, and high-speed flapping combine to generate a constant hovering force.
Aerodynamics of Hummingbird Flight
The physics of hummingbird flight relies on generating positive lift pressure with their wings. Here are some key aerodynamic mechanisms:
- Angle of attack – During downstroke, the wings are angled to deflect air downwards, resulting in upwards lift force.
- Wing inversion – At the bottom of each stroke, wings rotate to maintain positive angle of attack.
- Vortex generation – Airflows over the wings create circular vortices that provide additional lift.
- Wing profile – The curving top surface of hummingbird wings causes air to flow faster over the top, reducing pressure.
- Leading-edge vortex – At high angles, a spiral of air rolls over the wing’s leading edge, providing extra lift force.
Careful study of hummingbird wings and flight dynamics has revealed the various aerodynamic mechanisms that allow these tiny birds to hover and fly.
Conclusion
Most hummingbird species are lighter than a penny. But some larger hummingbirds may exceed the 2.5 gram weight of a U.S. penny. However, hummingbirds have evolved an incredibly efficient hovering ability that enables them to generate enough lift to overcome the force of gravity, regardless of their actual weight. So a hummingbird’s lightweight, aerodynamic wings provide a greater advantage than the small mass of a penny. Therefore, an average hummingbird can easily lift itself despite weighing slightly more than a penny. Their specialized flying abilities allow hummingbirds to hover and fly unlike any other birds. So a hummingbird is able to fly freely even if marginally heavier than a penny due to its diminutive size.