The calliope hummingbird (Selasphorus calliope) is the smallest breeding bird in North America and one of the smallest birds in the world, with females weighing just 2-3 grams on average. The species is named after the muse Calliope from Greek mythology. The female calliope hummingbird has a very distinctive appearance that sets it apart from other North American hummingbirds.
Size and Shape
The female calliope hummingbird is tiny, measuring just 2.75-3.25 inches (7-8 cm) in length on average. Its wingspan ranges from 4-4.5 inches (10-11 cm). This makes it smaller than other tiny hummingbirds like the ruby-throated hummingbird and the rufous hummingbird. The calliope female has a short, straight black bill and a long, slender body shape. Their tail is rounded and short compared to other hummingbirds.
The diminutive size and delicate build of the female calliope hummingbird reflects its adaptation for specialized nectar feeding. Along with their tiny size, calliopes have long tongues that they can extend to reach nectar deep inside flowers. Their wings beat 55-75 times per second, allowing them to precisely maintain hovering flight while feeding.
Plumage
The female calliope hummingbird’s plumage is primarily grayish-white to pale cinnamon in color. Here are some key features of their plumage:
- Throat and chin – White
- Breast and belly – White with scattered cinnamon-brown spots
- Crown and back – Grayish-brown
- Wings – Dusky with a faint cinnamon wash
- Tail – Dusky black, forked, with white tips on the outer tail feathers
Many people observe that the female calliope hummingbird resembles a dry leaf when perched. Their overall grayish-brown plumage provides good camouflage against bark and dried vegetation.
Distinguishing Features
Several key features can help distinguish the female calliope hummingbird from other similar hummingbird species:
- Very small size – The tiniest hummingbird in North America
- Short, straight black bill – Unlike the longer decurved bills of other species
- White throat/chin – Contrasts against the pale cinnamon breast
- Forked tail with white tips – A key identifier compared to other small hummingbirds
- Cinnamon spots on breast/belly – Create a speckled appearance on the underside
- Dusky wings – Lack the iridescence seen on males and other hummingbird species
Color Changes
The plumage of the female calliope hummingbird can appear to change color depending on viewing angle. The crown and back may flash an iridescent reddish-pink and the throat may appear light orange when sunlight hits at certain angles. However, these are not true color changes, but rather tricks of the light caused by refraction through the specialized feathers on these areas.
Light refraction off the crown and throat feathers leads some to claim that female calliopes transform from drab to colorful as they move. But the feathers themselves remain grayish-brown and white – they do not have any actual pigment color changes.
Immature Females
Younger female calliope hummingbirds may be identified by some key differences in their plumage compared to mature adults:
- Crown is darker gray-brown
- Throat has gray streaking
- Breast is pale gray, lacking cinnamon spots
- Belly has fewer spots which are darker cinnamon
- Tail is shorter with little to no white
These immature features are gradually replaced with adult characteristics as the birds molt and mature over their first year of life. By one year of age, the females attain their definitive plumage.
Geographic Variation
Across the calliope hummingbird’s breeding range, there are some regional variations in the female’s appearance:
| Region | Plumage Differences |
|---|---|
| Pacific Northwest | Browner overall with more rufous on head and tail |
| Rocky Mountains | Palest plumage with more white |
| Southwest Deserts | Brighter cinnamon spots on breast/belly |
| California | Darker tail with little white on tips |
However, these regional variations are quite subtle and female calliopes remain fairly consistent in appearance across their range.
Molting and Appearance Changes
Female calliope hummingbirds molt their plumage one feather at a time after the breeding season. Their appearance can change throughout the molting process, which lasts from July through September:
- Older feathers are dropped and replaced with new feathers
- Patchy look during active molting
- May temporarily lose the white tips on outer tail feathers
- Throat and crown often look scruffier
- By September-October, molt is completed
This molt results in brighter, fresher plumage that is maintained throughout the winter period. In the spring, females may undergo another quick partial molt before breeding to achieve their peak colorful breeding appearance.
Differences from Males
Male calliope hummingbirds look dramatically different than their female counterparts. Here are some key ways males and females differ in appearance:
- Males – Iridescent ruby-red throat, green crown, white breast
- Females – White throat with scattered brown spots, grayish-brown crown, pale cinnamon breast
- Males – Forked tail with purple-black center feathers
- Females – Forked tail with dusky black center feathers and white tips
- Males – Bright iridescent feathers on crown, throat, tail
- Females – Lack iridescent feathers, subdued grayish-brown plumage
The dramatic differences in coloration are related to camouflage needs. Dull-colored females are well-camouflaged while incubating eggs and raising young. Bright males are adorned for courtship displays to attract mates.
Behavioral Differences
Some key behavioral differences also exist between male and female calliope hummingbirds:
- Males – More aggressive and territorial, defending flower patches
- Females – Shyer, avoid conflict with males or other species
- Males – More active courtship displays, diving displays
- Females – Very brief courtships, quietly watch displays
- Males – Do not participate in child rearing
- Females – Build nest, incubate eggs, care for chicks
These differences in behavior align with the gender-based reproductive roles in this species. Females take on all parenting duties, while males focus energy on courtship and mate competition.
Conclusion
The tiny female calliope hummingbird can be identified by its very small size, short black bill, white throat and chin, cinnamon-speckled underparts, forked tail with white tips, and overall grayish-brown plumage. Immatures have some differences like more streaking on the throat and a shorter tail. Females lack any iridescent coloration found in the dramatic ruby-throated males. Their subdued plumage provides camouflage for nesting and feeding young. Though small, the remarkably hardy female calliopes migrate long distances and raise chicks on their own across mountainous western North America.
