The Bee Hummingbird is the world’s smallest bird, with an average length of just 2 inches from bill to tail. Despite its tiny size, this Cuban native is a fierce competitor when it comes to reproduction. The female Bee Hummingbird lays the smallest known bird egg in the world, measuring only 0.3 inches long and weighing 0.3652 grams on average. This incredible feat allows the diminutive hummingbird to produce enough offspring to sustain its populations amid the dangers of its environment.
In this article, we will explore the minuscule dimensions of the Bee Hummingbird egg and how it compares to eggs from other bird species. We will look at:
- The average size and weight of a Bee Hummingbird egg
- How their tiny eggs compare to other hummingbirds and birds
- Why their eggs must be so small
- How their eggs develop and hatch
- How the female incubates such a minute egg
Gaining a sense of scale for just how small the Bee Hummingbird egg is helps us appreciate the marvel of their reproduction. It’s hard to believe that the world’s smallest bird is able to sustain its species laying the world’s tiniest eggs, but the Bee Hummingbird has mastered the art of miniaturization.
Average Size of a Bee Hummingbird Egg
In terms of dimensions, a Bee Hummingbird egg measures:
- 0.3 inches (8 millimeters) long
- 0.2 inches (5 millimeters) wide
To put that in perspective, a Bee Hummingbird egg is only about the size of a coffee bean. It’s smaller than a grape or a pea.
The diminutive size is believed to be the smallest of any known bird egg, both in absolute size and relative to the adult bird’s body size. For its tiny 0.057-0.071 ounce (2-2.5 gram) body weight, a full-sized Bee Hummingbird egg represents over 5% of its weight. Most other bird eggs represent only 2-4% of an adult’s body weight.
Weight of a Bee Hummingbird Egg
In terms of weight, a Bee Hummingbird egg averages just 0.012-0.016 ounces (0.3652 grams).
This is what a Bee Hummingbird egg weighs compared to other tiny items:
- 1/4 the weight of a U.S. dime (2.268 grams)
- Half the weight of a U.S. penny (2.500 grams)
- The same weight as 4 paper clips
- The same weight as 3 grains of uncooked rice
As you can see, the Bee Hummingbird produces an extraordinarily tiny and lightweight egg compared to most other birds. Their miniature size helps the egg fit into the female’s tiny body until hatching.
Comparison to Other Hummingbird Eggs
Bee Hummingbird eggs are smaller than any other hummingbird species’ eggs. Here’s how they compare:
| Species | Egg Size | Egg Weight |
|---|---|---|
| Bee Hummingbird | 0.3 in long x 0.2 in wide | 0.3652 g |
| Calliope Hummingbird | 0.5 in long x 0.25 in wide | 0.26 g |
| Broad-tailed Hummingbird | 0.5 in long x 0.33 in wide | 0.39 g |
| Rufous Hummingbird | 0.6 in long x 0.4 in wide | 0.49 g |
As the smallest hummingbird species, it’s no surprise that the Bee Hummingbird also has the smallest hummingbird egg. Their eggs are less than half the size of the next smallest hummingbird egg, from the Calliope Hummingbird.
The largest hummingbird egg comes from the Giant Hummingbird of South America, measuring a full inch long and weighing 2 grams – over 5 times heavier than the bee’s egg!
Comparison to Other Bird Eggs
Compared to all bird species, the Bee Hummingbird egg is absolutely tiny:
| Bird Species | Egg Size | Egg Weight |
|---|---|---|
| Bee Hummingbird | 0.3 in long x 0.2 in wide | 0.3652 g |
| Yellow-breasted Chat | 0.8 in long x 0.6 in wide | 1.75 g |
| Blue Tit (UK) | 0.7 in long x 0.5 in wide | 1.9 g |
| American Robin | 1.1 in long x 0.8 in wide | 3.4 g |
| Red Junglefowl (Chicken) | 1.5 in long x 1.1 in wide | 4.5 g |
| Ostrich | 6 in long x 5 in wide | 3 lb |
The Bee Hummingbird egg is over 5 times smaller than the egg of a similarly tiny Yellow-breasted Chat. It’s nearly 7 times smaller than a Robin’s egg and a whopping 12 times smaller than a chicken egg!
On the opposite end of the spectrum, an ostrich egg is over 200,000 times heavier than the bee’s microscopic egg. This comparison shows just how incredibly tiny the Bee Hummingbird egg is for the bird world.
Why Their Eggs Are So Small
There are several key reasons why Bee Hummingbird eggs have evolved to be so tiny:
Small Adult Body Size
The Bee Hummingbird is the world’s smallest bird, so it stands to reason that its eggs would be equally tiny. At just 2 inches long and 2 grams in weight, the adult bird is not much bigger than its 0.3 inch egg. The egg size has evolved to fit within the female’s petite body.
Nest Space Limitations
Bee Hummingbirds build a thimble-sized nest out of spider webs, lichens, and plant down. The tiny nest cup is only about 2 inches wide – just big enough for two minuscule eggs. Large eggs simply won’t fit in theirtiny nests.
Fast Development Required
Smaller eggs allow for faster embryonic development. The Bee Hummingbird chick must grow quickly to survive in its vulnerable nest. A smaller egg size means less time is needed in the egg stage.
Extreme Egg Losses
Predators, storms, and other dangers result in high egg loss rates for hummingbirds. Smaller eggs allow the female to lay more in a season to compensate, maximizing her chances of procreation success.
So in summary, the Bee Hummingbird egg is teeny-tiny because of the small adult size, nest limitations, need for speedy development, and high rates of egg loss. Their tiny egg is an incredible adaptation allowing their survival as the world’s smallest warm blooded animal.
Development and Hatching
Despite their micro-size, Bee Hummingbird eggs still undergo the same stages of embryonic development as other birds’ eggs:
Fertilization
The egg is fertilized internally by the male sperm prior to laying. Fertilization takes place within the female’s reproductive tract known as the oviduct.
Cell Cleavage
Once laid, cell division and DNA replication result in rapid cell multiplication. Cleavage divides the single cell into multiple cells that differentiate to form specialized tissues and organs.
Organogenesis
The basic tissue layers organize into major organ systems like the brain, skeleton, skin, and digestive system to form the basic structures of the body.
Growth
The tissues and organs grow rapidly, fueled by the energy in the yolk. The body of the chick takes shape during this stage.
Hatching
After 13-17 days of development, the fully formed chick uses its egg tooth to peck a hole in the eggshell. It can take 12-24 hours for the chick to fully emerge from its 0.3 inch shell.
Despite having a head start from internal fertilization, the Bee Hummingbird still needs a full two weeks of external development before hatching. Those two weeks are critical, with the parents constantly incubating the pea-sized eggs to protect the fragile embryos inside.
Incubation By The Mother
The female Bee Hummingbird is responsible for incubating her tiny eggs, keeping them at the proper warmth and humidity. Considering their miniscule size, it’s incredible that the eggs can survive:
Body Heat
The female’s high body temperature (105 F / 41 C) allows her to transfer enough warmth directly to the tiny eggs when she sits on the nest. Her metabolic rate increases by around 30% during incubation.
Constant Vigilance
The female must incubate nearly continuously, leaving the nest unattended for only a few minutes at a time. Abandoning the eggs for longer would risk their temperature dropping too low. She cannot risk the embryos getting chilled.
Insulated Nest
The cozy nest provides some degree of insulation to help maintain the eggs’ temperature when the female is away for a few minutes to eat. The nest’s small size and shielded location provide protection.
No Male Assistance
Without the male to take turns incubating, the female shoulders 100% of the responsibility. She must be diligent for the entire 13-17 day period until hatching.
High Calories
The female boosts her intake of nectar and small insects to provide enough energy for such demanding incubation of her tiny eggs.
Through heroic parental care and ideal nest construction, the female Bee Hummingbird is able to keep her micro-eggs at just the right conditions for successful hatching. It’s amazing she’s able to hatch eggs that are only slightly larger than garden peas!
Conclusion
The Bee Hummingbird egg stands as a true marvel of miniaturization in the natural world. By laying the tiniest known bird egg at just 0.3 inches long and 0.3652 grams, the world’s smallest bird is able reproduce despite the inherent challenges of its diminutive stature. The Bee Hummingbird’s egg has evolved to perfectly match both the female’s body limitations and the space constraints of an extremely small nest. These tiny eggs develop rapidly and benefit from the female’s vigilant incubation to successfully hatch even in very precarious conditions. The minuscule size allows the female to lay more eggs per clutch, maximizing chances of procreation even when facing high egg mortality circumstances. Understanding the extreme tininess of the Bee Hummingbird egg provides insight into the adaptive extremes of these tiny birds and appreciation for the miracles of nature’s designs. The Bee Hummingbird aptly demonstrates that even the greatest accomplishments can come in the smallest packages.
