Calliope Hummingbird: Smallest Bird in the US, and ID

Quick Facts

Scientific name: Selasphorus calliope, formerly Stellula calliope

Length: 3.1 to 3.5 inches

Wingspan: 4.1 to 4.3 inches

Weight: 2.3 to 3.4 grams

Range: breeds in the mountains from southern British Columbia and Alberta to Colorado and southern California; the entire population winters in southwestern Mexico

Migration: around 5,000 miles a year, in a loop

Longevity record: a female of at least 8 years and 1 month, banded in Idaho in 2007 and recaptured there in 2014

Population: around 4.5 million, essentially stable

Conservation status: Least Concern, but on the Yellow Watch List for restricted range

A Note on the Name

You will find this bird under two scientific names, and both are correct depending on the age of the source.

It was long placed in a genus of its own, Stellula, meaning “little star”, on the strength of how different it looked from everything else. Genetic work published by McGuire and colleagues in 2009 showed it sits inside Selasphorus, alongside the Rufous, Broad-tailed and Allen’s Hummingbirds. Selasphorus calliope is the current name.

Plenty of field guides, state wildlife pages and older references still say Stellula. If you meet that name, it is the same bird.

How to Identify a Calliope Hummingbird

The male is unmistakable if you get a clear look, because no other North American hummingbird has a gorget like his. Instead of a solid patch of colour, his throat carries separate magenta rays streaming down over a white background, like thin ribbons laid on snow. Above that he is green, below he is white.

As with every gorget, the magenta only fires when light strikes at the right angle. In poor light the rays read as dark streaks or vanish entirely, so the structural trick behind hummingbird colour is worth knowing before you go looking.

The female is greener above with a peachy wash across her underparts and fine green stippling on the throat. That peachy tone is warmer than a female Anna’s or Black-chinned shows, though it is subtler than the rufous of the Selasphorus females.

Size and shape do most of the work for both sexes. This is a very small, hunched bird with short wings, a short tail and a bill that is noticeably thin and short even by hummingbird standards. Perched, it looks compressed, as though someone has pushed it down from above. Next to a Broad-tailed in the same meadow the difference is obvious.

Similar Species

Broad-tailed Hummingbird shares much of the same mountain range and is the usual confusion. The male Broad-tailed has a solid rose-magenta throat rather than separate rays, and he is noticeably larger and longer-tailed. Adult male Broad-tailed also make a loud metallic wing trill in flight that the Calliope does not.

Rufous Hummingbird males are coppery orange across the back and flanks, which the Calliope never shows.

Allen’s Hummingbird overlaps only at the western edge of the Calliope’s range and, like Rufous, carries orange tones.

Costa’s Hummingbird is also tiny, but the male’s violet gorget flares into a solid moustache rather than breaking into rays.

The article on North American species sets out the whole cast, and the size extremes of the family put this bird’s dimensions in perspective.

Range and Habitat

Calliope Hummingbirds breed in the mountain West, from southern British Columbia and Alberta south through Washington, Oregon, Idaho, Montana and Wyoming. From there the range continues into Colorado, Nevada, Utah and the higher parts of California.

The breeding band runs between roughly 4,000 and 11,000 feet. They favour mountain meadows, willow and alder thickets along streams, and open forest recovering after fire. Burned ground that has come back in shrubs and wildflowers is particularly good, which is a useful thing to know if you are looking for them.

The Pacific Northwest, Rocky Mountain and California guides all cover where and when to look across those regions.

In winter they occupy thorn forest and pine-oak forest in southwestern Mexico. Every single Calliope Hummingbird in the world spends the non-breeding season there, which matters more than it first appears.

The Smallest Long-Distance Migrant on Earth

A Calliope weighing under three grams travels around 5,000 miles a year in a large oval.

Northbound in spring, the birds move up the Pacific lowlands, keeping to the warmer low country while the mountains are still under snow. Southbound in late summer, they swing inland and drop south through the Rocky Mountains, following the late alpine wildflower bloom down the spine of the continent. It is the same clockwise pattern the Rufous Hummingbird uses, and for the same reason: it keeps the bird in flowers at both ends of the year.

No smaller bird anywhere is known to migrate this far. The mechanics of how hummingbirds manage journeys like this are covered separately, but the short version is fat, timing and an ability to shut the body down overnight.

Surviving the Mountain Night

Breeding at 9,000 or 10,000 feet means freezing nights in June, and a two-and-a-half gram body has almost nothing in reserve.

The answer is torpor. The bird drops its body temperature and metabolic rate for hours at a time and restarts at dawn. The full physiology of torpor is covered separately, along with where hummingbirds actually spend the night.

The Dive

The male’s courtship display is a steep climb and a fast descent. He rises to around 20 metres, roughly 66 feet, then dives past the perched female.

The sound that comes with it is partly mechanical and partly vocal. Air rushing over the wing and tail feathers at speed makes them vibrate, a mechanism called sonation, and the male adds a vocal component on top. That mixture is unusual. The Anna’s chirp is purely tail feathers, and the Broad-tailed’s trill is purely wing feathers. More on how hummingbirds make sound, with and without their voices, is covered separately.

Breeding

The female does everything, as in every hummingbird species.

She builds a well-insulated cup of soft plant down, camouflaged outside with lichen, moss or bark fragments and bound with spider silk. The finished nest is tiny, an inch and a half to under two inches across on the outside. The inner cup is about three quarters of an inch wide and just over half an inch deep.

Placement is the clever part. She usually builds on an evergreen branch, in lodgepole pine, Douglas-fir or western red cedar, anywhere from 6 to 39 feet up. She often chooses a spot where old pine cones grew. A small lichen-covered lump on a conifer branch reads as a cone rather than a nest, which is the point.

She will also reuse a nest, or build a new one on top of an old one, in later attempts. At altitude, where the snow-free season is short, saving several days of construction matters.

She lays two eggs, incubates them for 15 to 16 days, and the young leave the nest 18 to 21 days after hatching. She may raise one or two broods in a season. The full breeding cycle is covered separately, and how long the survivors go on to live is a separate question again.

What It Eats

Nectar from mountain wildflowers is the fuel. Protein comes from small insects taken on the wing, a technique called hawking.

The third source is the interesting one. Calliopes feed regularly at sapwells, the neat rows of holes that sapsuckers drill into tree trunks. In the high country in early spring, before much is in bloom, those wells can be the only reliable sugar available. The bird is effectively stealing from a woodpecker. The balance between nectar and insects works the same way across the family.

Stable, and on a Watch List

These two things sound contradictory and are not, and the reason is worth understanding.

The population is around 4.5 million and essentially flat. Breeding Bird Survey data show a decline of about 0.06 percent between 1968 and 2019, which is close enough to zero to be noise. The IUCN lists the species as Least Concern.

Yet Partners in Flight scores it 14 out of 20 on the Continental Concern Score, the same as the Rufous Hummingbird, which has lost 72 percent of its population. And it sits on the Yellow Watch List.

The reason is not the trend. It is the concentration. The entire world population of this species winters in southwestern Mexico, in a comparatively small area. A species with everything in one basket is exposed in a way that a stable population figure does not reveal. A bad enough event in the wintering range, whether habitat clearance, drought or a shifted climate, would hit every Calliope Hummingbird alive.

That is a different kind of risk from the one facing the Rufous, and the wider pressures on hummingbirds article covers both.

Attracting Calliope Hummingbirds

If you live in the mountain West within the breeding range, or along the migration corridors, this is a realistic garden bird.

They come to feeders readily. Use plain white sugar in a one-to-four ratio with water and nothing else, and clean the feeder often. The nectar recipe and feeder care page covers the detail.

Plant for them as well. Mountain natives such as penstemon, paintbrush, columbine and scarlet gilia all work, and they are better long-term value than a feeder. The article on attracting hummingbirds covers planting and placement, and when to put feeders out and take them down covers the local timing.

One practical note. Calliopes are small and are routinely bullied off feeders by Rufous and Broad-tailed. Two or three feeders spaced well apart, ideally out of sight of one another, will let the smallest bird in the country get a turn.

Frequently Asked Questions

What is the smallest bird in the United States?

The Calliope Hummingbird, at 3.1 to 3.5 inches long and 2.3 to 3.4 grams. It is the smallest bird breeding anywhere in the United States or Canada.

How do I identify a Calliope Hummingbird?

Look for a very small, hunched hummingbird with a short bill and short tail. Males have separate magenta rays streaming down a white throat, unlike the solid gorgets of every other North American species. Females are green above with a peachy wash below.

Is it Stellula or Selasphorus?

Selasphorus calliope is current. It was moved out of the genus Stellula after genetic work published in 2009. Older sources still use the old name for the same bird.

How far does a Calliope Hummingbird migrate?

Around 5,000 miles a year, in an oval: north up the Pacific lowlands in spring, south through the Rockies in late summer. It is the smallest long-distance migrant bird in the world.

Where do Calliope Hummingbirds spend the winter?

Southwestern Mexico, in thorn forest and pine-oak forest. The entire world population winters there.

How do they survive freezing mountain nights?

By entering torpor, dropping body temperature and metabolic rate for hours and restarting at dawn.

Are Calliope Hummingbirds endangered?

No. The population is around 4.5 million and stable, and the IUCN lists the species as Least Concern. It is on the Yellow Watch List, but for restricted range rather than decline, because the whole population winters in one part of Mexico.

Conclusion

There is a temptation to treat the Calliope as a curiosity, the smallest bird on the list, and leave it there. The size is the least interesting thing about it. This is a bird that nests at 10,000 feet, hides its nest by making it look like a pine cone, and steals sap from woodpeckers. It also flies the length of a continent twice a year on a body weighing less than a nickel. Nothing smaller has ever been found doing any of it.