Birds
Bee Hummingbird
Mellisuga helenae · also called bee hummingbird, zunzuncito, Helena hummingbird
The bee hummingbird is the smallest bird on Earth — a Cuban species so tiny it is regularly mistaken for a large bee, and light enough that a pair of them would not tip a kitchen scale off zero. Living at that size pushes a warm-blooded animal to its physiological limits.
Overview
The bee hummingbird is endemic to Cuba and the Isla de la Juventud, where it lives in forest edges, scrub, and gardens with plenty of flowering plants. Males are the smaller sex, around 2 grams; females are slightly larger. In breeding condition the male has an iridescent pink-red head and throat with pointed side feathers; outside the breeding season, and in females, the plumage is a plainer blue-green and white.
Life at the edge of what is possible
Everything about the bird is scaled to extremes. Its wings beat about 80 times a second, tracing a figure-eight that generates lift on both the forward and backward stroke and lets it hover, fly backwards, and fly briefly upside down. Its heart reaches 1,200 beats a minute. To power this it must feed almost continuously — roughly 1,500 flower visits a day, eating about half its body weight in nectar, plus small insects and spiders for protein — and it pollinates many Cuban plants in the process.
Surviving the night
A body this small cannot store enough fuel to last a cold night. Each evening the bee hummingbird enters torpor: its temperature falls, its heart slows to as few as 50 beats a minute, and its metabolism nearly stops. At dawn it shivers itself back to operating temperature over about 20 minutes and starts feeding again.
Nesting
The female builds a cup nest about 2.5 centimetres wide from cobweb, plant down, bark flakes, and lichen, binding it to a twig and stretching it as the two pea-sized chicks grow. She raises them alone.
Status
The bee hummingbird is Near Threatened and declining. The single threat that matters is habitat loss — the clearing of Cuba’s native forest and shrubland for farming — which has broken its range into fragments. It readily uses flower-rich gardens, and it is protected in Cuba, where it is a national emblem known as the zunzuncito.
Bee Hummingbird: common questions
How small is the bee hummingbird really?
A male bee hummingbird is about 5.5 centimetres from bill tip to tail tip and weighs roughly 2 grams — less than a Canadian penny or a US dime, and about the same as two paperclips. Much of that length is bill and tail; the body itself is smaller than many bees, which is where the name comes from. It is not only the smallest bird but one of the smallest warm-blooded animals of any kind, close to the theoretical lower limit for a bird because a smaller body loses heat too fast to sustain.
How fast does its heart beat and its wings move?
At rest the heart runs at roughly 500 beats per minute; in active flight it can reach about 1,200 — 20 beats every second. The wings beat around 80 times per second in ordinary flight and up to about 200 times per second when a male is performing his diving courtship display, producing the high hum that gives hummingbirds their name. To fuel this the bird must eat almost constantly, visiting on the order of 1,500 flowers in a day and consuming roughly half its body weight in nectar.
How does such a tiny bird survive the night?
It cannot store enough energy to power its metabolism through eight hours of darkness without feeding, so on cool nights it enters torpor — a controlled, hibernation-like state in which its body temperature falls, its heart rate drops to as low as 50 beats per minute, and its energy use plummets. It looks almost dead. Around dawn it warms itself back up, shivering, over 20 minutes or so, and resumes feeding. Torpor is a routine, nightly survival tactic for the species.
Is the bee hummingbird endangered?
It is listed as Near Threatened and its population is decreasing. The bird exists only in Cuba, and its problem is habitat — the natural forest and shrubland it depends on, rich in the small native flowers it feeds from, has been widely cleared for agriculture. It does use gardens and forest edges with suitable flowers, which helps, but its range is now fragmented. It is legally protected in Cuba and is a point of national pride, known locally as the zunzuncito.