What bird is smaller than a Bee Hummingbird?

The Bee Hummingbird, scientifically known as Mellisuga helenae, is the smallest living bird in the world. Native to Cuba, this tiny bird measures just 5-6 centimeters (2-2.4 inches) long and weighs a mere 1.6-1.9 grams (0.05-0.07 ounces). Known for its rapid wing beats and ability to hover in midair, the Bee Hummingbird’s minuscule size poses an interesting question – are there any birds that are even smaller than this tiny feathered creature?

The Bee Hummingbird Holds the Record for Smallest Living Bird

According to the Guinness Book of World Records, the Bee Hummingbird currently holds the record for the smallest living bird in terms of length. No other living bird species has been verified to be smaller than the Bee Hummingbird, although a few extinct species and some unverified claims of tiny birds exist.

The Bee Hummingbird rivals the Cuban Emerald hummingbird as the smallest hummingbird species in the world. Here is a comparison of their sizes:

As you can see, the Bee Hummingbird is over 2 centimeters shorter and nearly a full gram lighter than the Cuban Emerald, confirming its status as the smallest. No other living bird comes close to rivaling its minuscule proportions.

Extinct Species Smaller than the Bee Hummingbird

While no living bird has been verified to be smaller than the Bee Hummingbird, some extinct species are believed to have been tinier:

• The Cuban Bee Hummingbird (Mellisuga helenae minima) was a subspecies of Bee Hummingbird that lived in prehistoric Cuba. At just 2 inches long and weighing 0.07 ounces, it was likely smaller than today’s Bee Hummingbird.
• The Long-legged Buzzer (Nesotrochis debooyi) lived in prehistoric Bahamas. It stood just 1.5 inches tall and remains one of the tiniest birds ever discovered.
• The Pigmy Owl (Xenoglaux loweryi) lived in the Caribbean during the Ice Age. It stood about 2 inches tall, with a weight of around half an ounce.

Unfortunately, these diminutive birds are now extinct. But their fossil records confirm the existence of birds smaller than the living Bee Hummingbird.

Unverified Claims of Small Birds

There have also been some unconfirmed reports of tiny birds that, if proven, would steal the Bee Hummingbird’s record:

• The Philornis flycatcher is reported to live on the Galapagos Islands. At just 2 inches long, some accounts claim it is smaller than the Bee Hummingbird but solid verification is lacking.
• An expedition to the Andes mountains of Peru in 2009 claimed sightings of a new species of hummingbird smaller than a Bee. But the findings remain unproven.
• There are occasional reports of a rare hummingbird living in India that is just 2-3 cm long. But these lack scientific documentation.

While intriguing, these claims remain unverified by science. Some may represent cases of mistaken identity or exaggeration. Unless solid proof emerges, the Bee Hummingbird keeps its title as smallest.

Why the Bee Hummingbird is so Tiny

There are a few key reasons why the Bee Hummingbird evolved to be so remarkably tiny:

• Adaptation to flower sizes – Many of the flowers the Bee Hummingbird feeds from are themselves very tiny. Its petite size allows it to efficiently feed.
• Limited resources – There is fierce competition for nectar in its Caribbean habitat. Being highly maneuverable helps the Hummingbird exploit small flowers.
• Predator avoidance – Its diminutive size makes it easy to evade predators and hide its tiny nest.
• Heat regulation – A smaller body mass allows the Hummingbird to more easily dissipate heat while flying.

These evolutionary pressures drove the Bee Hummingbird to become as tiny as physically possible for flying birds. No living species has been able to surpass its diminutive proportions.

Bird Species Barely Larger than the Bee Hummingbird

While no living birds have been verified as smaller than the Bee Hummingbird, a few species come close in their minute proportions:

These tiny birds demonstrate just how petite the Bee Hummingbird is compared to most other bird species. While marginally larger than the Bee Hummingbird, these species represent some of the smallest birds apart from it.

Metabolic Limitations on Tiny Bird Sizes

There appear to be some metabolic constraints that set a lower limit on just how small birds can become. Extremely tiny size creates challenges for thermoregulation, energy usage, and flight.

Some key metabolic limitations include:

• Higher surface area to volume ratio – Leads to faster heat loss.
• Very rapid heartbeat – Required to power flight muscles.
• Limits on muscle mass and power output.
• Difficulty dissipating body heat while flying.
• Increased risk of starvation due to high metabolism.

Researchers theorize the Bee Hummingbird is very close to the lower viable limit, given basic avian physiology. This helps explain why no living birds have yet been found that are smaller.

The Search Continues for Even Tinier Birds

While no bird smaller than the Bee Hummingbird exists today, the search is still on to potentially find competitors to its title of “world’s smallest bird.” Here are some key areas researchers continue to investigate:

• Undiscovered tropical regions – Vast rainforests and remote islands may still hide unknown tiny bird species.
• Fossil specimens – Ancient extinct birds may be uncovered that were tinier than the Bee Hummingbird.
• Improved measurement methods – New technologies may enable more precise size measurements to uncover smaller species.
• Hoaxes and exaggerations – Claims of minute birds must be scientifically verified to be proven genuine.

The scientific community takes continued interest in the question of just how small birds can evolve. Only time will tell if another species can take the Bee Hummingbird’s crown as the world’s smallest bird.

Conclusion

The Bee Hummingbird has good claim to the record of world’s smallest living bird. No living species has been conclusively verified as smaller, though some fossil evidence suggests a few extinct species were tinier. Evolutionary pressures and metabolic limitations seem to constrain how minute bird sizes can become. While the Bee Hummingbird’s title is safe for now, the search continues for potentially smaller species. Any scientific discovery of a bird smaller than a Bee Hummingbird would be a remarkable find, but also raise new questions about the lower limits to avian proportions. For its truly tiny size, the Bee Hummingbird aptly earns its reputation as one of the most diminutive and unique birds on earth.