The bee hummingbird, Mellisuga helenae, is the smallest bird in the world. It is a member of the family Trochilidae, which encompasses all hummingbirds. Hummingbirds are unique among birds for their ability to hover in midair and fly backwards as well as forwards. They are nectar-feeding birds and have special adaptations for feeding on nectar, like a long bill and a specially adapted tongue.
The bee hummingbird is endemic to Cuba and measures just 5-6 cm (2-2.5 in) in length with a 1.6-1.9 cm (0.63-0.75 in) wingspan. Their extremely small size and rapid wingbeats that can reach up to 200 flaps per second make them a marvel of nature. But in what order do these tiny, spectacular birds belong in the classification of life?
Classification of the Bee Hummingbird
All living organisms, including the bee hummingbird, are classified into a taxonomy system that ranks groups from broad to specific. The taxonomy system consists of the following major ranks from broadest to most specific:
- Domain
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
The bee hummingbird is classified in the following taxonomic hierarchy:
- Domain: Eukarya
- Kingdom: Animalia
- Phylum: Chordata
- Class: Aves
- Order: Apodiformes
- Family: Trochilidae
- Genus: Mellisuga
- Species: Mellisuga helenae
Therefore, the bee hummingbird’s order is Apodiformes. Let’s look at some key details on this order.
Key Facts About the Apodiformes Order
Here are some key facts about the Apodiformes order that the bee hummingbird belongs to:
- The order name Apodiformes means “footless” in Latin and refers to the small, weak feet of these birds.
- It contains just one suborder, Trochiliformes, which encompasses hummingbirds and swifts.
- There are approximately 450 species in this order.
- The group has a worldwide distribution.
- Along with hummingbirds, the order contains swifts, treeswifts, and crested swifts.
- Unique characteristics of Apodiformes include wings adapted for continuous flight, tiny non-grasping feet, and a wide gape.
- These are mainly aerial birds that feed on insects caught in flight or nectar.
So in summary, Apodiformes refers to the order containing swifts, treeswifts, hummingbirds and crested swifts. The bee hummingbird fits within this order that is defined by aerial masters with adaptations for aerial life and feeding.
Evolutionary History and Relationships
Hummingbirds belong to an ancient lineage that branched off early in the evolution of birds. The small anatomical size of hummingbirds limits what can be gleaned from the fossil record, but it is believed they evolved around 22-42 million years ago during the Eocene epoch.
DNA evidence suggests hummingbirds are a sister group to swifts within the order Apodiformes. Both share common anatomical traits like short legs suitable for clinging rather than walking or perching. However, they diverged sometime during the Cenozoic era such that swifts retained long, crescent-shaped wings ideal for continuous flight, while hummingbird wings adapted for the brief but intense bursts of hovering and maneuvering required during feeding.
Other bird groups like passerines share common ancestry with hummingbirds, but genetically they diverged some time near the Cretaceous–Paleogene boundary around 66 million years ago. So while passerines comprise around 60% of all living bird species today, evolutionarily they are only distant relatives to hummingbirds. Morphological and genetic analysis continue to reveal insights into how hummingbirds evolved into a distinct, specialized group within the order Apodiformes.
Unique Adaptations of Hummingbirds
Hummingbirds display unique anatomical and physiological adaptations that enable them to hover and thrive on calorie-rich sugary nectar:
- Wings – Their specially articulated shoulder joints allow their wings to rotate in a full arc and even rotate backwards. This lets them achieve the only true hovering by birds and also to fly in omnidirectional patterns.
- Flight Muscles – Up to a third of their total muscle mass is dedicated to powering flight, the highest proportion in the animal kingdom.
- Heart Rate – Hummingbirds have the highest metabolism of all animals. At rest, their heart rate can be 500 beats per minute and over 1200 bpm during flight.
- Tongue – Their tongue has tubes that suck up nectar via capillary action. The tongues also have forked tips suited to the shape of flowers.
- Body Size – Many species, including the Bee Hummingbird, are extremely small. This allows them to hover in small spaces to access nectar.
- Feet – Their feet are only suitable for perching rather than walking. The toes are usually adapted to tightly grip branches.
These characteristics all enable hummingbirds to hovers near flowers for feeding on nectar, the key energy source that powers their unique lifestyle.
Habitat and Feeding
Most hummingbird species are found in tropical and subtropical habitats in Central and South America. However, some species also thrive in temperate climates during the summer across western North America and Canada.
Feeding is a near-constant activity for hummingbirds. Their high metabolism requires immense amounts of daily energy intake from sugars in floral nectar and tree sap. Hummingbirds use their specialized tongue to drink nectar while hovering precisely in front of flowers. Some species also consume insects for protein and nutrients.
A key mutualist relationship exists between hummingbirds and the plants they feed from. The birds obtain food, while plants are pollinated by the hummingbirds that carry pollen on their feathers and heads. Hummingbird-pollinated plants have coadapted with certain hummingbird species, leading to specialized flower shapes and colors. Thus, hummingbirds play a vital role in plant reproduction through their role as pollinators in many ecosystems.
Bee Hummingbird: World’s Smallest Bird
The Bee Hummingbird’s tiny size sets it apart, even among hummingbirds. Native only to Cuba, these tiny birds measure just 2 inches long and weigh 1.6-2 grams. This makes them not only the world’s smallest hummingbird, but the smallest living bird species on earth.
Despite their extreme miniaturization, bee hummingbirds still exhibit typical hummingbird characteristics:
- Short buzzing wings beating up to 200 times per second
- A long bill suited to probing flowers
- A diet of nectar and pollen
- Vivid iridescent plumage, in this case bright emerald green on the head and back
True to their name, bee hummingbirds are smaller than some bee species. Yet they share a key role with bees as pollinators of various flowering plants in Cuba. Their tiny size allows them to access nectar from flowers unreachable by larger pollinators.
While the evolutionary drivers of their miniature size are still not certain, being diminutive likely helps bee hummingbirds exploit certain small flowering plants. They prefer feeding from low-growing flowers and shrubs. As the world’s smallest bird, the bee hummingbird still impressively exhibits all the characteristic speed, agility, and adaptations that define its ancient order.
Threats and Conservation
Most hummingbird species are not considered threatened currently. Their ability to fly long distances helps them evade immediate threats. However, habitat loss in South America could put greater pressure on populations in the future. Other potential hazards that could impact hummingbirds include:
- Pesticides – Contamination of nectar sources can pose a risk
- Urbanization – Human infrastructure can remove natural food sources
- Climate Change – Flower timing and nectar production could be disrupted
- Predators – Hummingbirds fall prey to insects, reptiles, and other birds
Protecting natural hummingbird habitats and food sources will be key for conservation. Measures in some regions involve planting native flowers known to benefit hummingbirds. Public participation in projects like the North American Breeding Bird Survey also helps monitor population trends over time.
For the Bee Hummingbird specifically, its small range in Cuba increases vulnerability. But ongoing conservation efforts have helped stabilize the population at a low-risk level for now. Expanding protected areas and managing development will remain important in Cuba to ensure this tiny bird has a future.
| Taxonomic Rank | Category |
|---|---|
| Domain | Eukarya |
| Kingdom | Animalia |
| Phylum | Chordata |
| Class | Aves |
| Order | Apodiformes |
| Family | Trochilidae |
| Genus | Mellisuga |
| Species | Mellisuga helenae |
Conclusion
In summary, the bee hummingbird’s taxonomy classifies it in the order Apodiformes along with swifts and other hummingbirds. This ancient order dates back over 40 million years and is defined by aerial agility and hovering flight. As the world’s smallest bird, the Bee Hummingbird exhibits typical hummingbird adaptations like rapid wingbeats, specialized feeding, iridescent plumage, and diminutive size. While not currently threatened, all hummingbirds face potential habitat and food source loss from human impacts and climate change. Continued conservation efforts aimed at protecting floral resources and nesting habitats will help ensure the bee hummingbird retains its crown as the tiniest avian pollinator on Earth. Understanding the taxonomy and evolutionary history of these avian wonders allows us to better appreciate the diversity of the natural world.
