The Ruby-crowned Kinglet (Regulus calendula) is a very small songbird, measuring only 4-5 inches in length and weighing 5-10 grams. This tiny bird can be identified by several key characteristics:
Appearance
The Ruby-crowned Kinglet has olive-green plumage on its upperparts and white underparts. As the name suggests, adult males have a distinctive reddish-orange crown patch on the top of their heads. This bright crest is usually concealed, but males will raise it when excited or aggressive. Females lack the colored crown patch.
Both sexes have two white wing bars visible during flight. Their eyes are black and they have a long, thin bill. Their tails are notched at the tip. Juveniles appear similar to adult females, but with some buffy streaking on the underparts.
Size and Weight
Ruby-crowned Kinglets are one of the smallest songbirds in North America. Their diminutive size helps them feed on tiny insects and spiders.
Measurement | Size |
---|---|
Length | 4-5 inches |
Wingspan | 7-8 inches |
Weight | 5-10 grams |
Voice and Sounds
Ruby-crowned Kinglets have a surprisingly loud voice for such tiny birds. Their most common call is a high-pitched, repetitive “tseet.” They also have a buzzy, whistled song and an aggressive “chek” vocalization.
During the breeding season, males sing a fast-paced warbling song to declare their territory or attract a mate. The song consists of a jumble of chirps, pops, and whistles.
Habitat
Ruby-crowned Kinglets are found in coniferous or mixed forests across North America. They prefer habitats with tall trees and dense undergrowth. During migration and winter, they may also be found in deciduous woods, parks, and backyards with appropriate vegetation.
Kinglets build cup-shaped nests high up in the dense branches of conifers. Their nests are well-hidden and made of mosses, lichens, spider webs and other soft materials.
Behavior
Ruby-crowned Kinglets are active, acrobatic foragers. They constantly flutter through vegetation to grab tiny insects and spiders. Their movements are rapid and they rarely sit still for long.
They have high metabolisms and must feed frequently. Cold winter nights are challenging for these tiny birds, so they often enter torpor to conserve energy.
Kinglets are solitary outside of the breeding season. They may join mixed flocks with other songbirds like chickadees or nuthatches. Despite their small size, they are daring and may mob or harass much larger birds.
Diet
The diet of Ruby-crowned Kinglets consists almost exclusively of small insects and spiders. Some of their favorite prey includes:
- Spiders
- Aphids
- Caterpillars
- Flies
- Moth eggs
- Beetles
- Tree sap
They use their thin, pointed bills to probe into crevices and glean tiny morsels. They are expert hover-gleaners, plucking prey from foliage while hovering in mid-air. Kinglets will also occasionally eat berries and tree sap.
Breeding and Nesting
Ruby-crowned Kinglets breed in northern forests from April to July. They are monogamous and solitary nesters.
Interestingly, males contribute very little to building the nest or raising young. The female chooses a nest site and does most of the construction herself. She builds an elegant, lichen-covered cup nest high in a conifer.
The female lays 5-12 tiny white eggs and incubates them for about 14 days. Hatchlings are altricial – naked and helpless. The female broods and feeds the chicks for up to 18 days until they fledge.
Migration
Ruby-crowned Kinglets are migratory birds, traveling between northern breeding and southern wintering grounds each year. Their migrations cover thousands of miles.
Here are key facts about their migration timing and routes:
- Spring migration runs March to May.
- Fall migration occurs August to November.
- They migrate at night, navigating by the stars.
- Common migration routes include Central America and southern U.S. states.
Taxonomy
The Ruby-crowned Kinglet belongs to the following scientific classification:
- Kingdom: Animalia
- Phylum: Chordata
- Class: Aves
- Order: Passeriformes
- Family: Regulidae
- Genus: Regulus
- Species: Regulus calendula
There are four recognized subspecies across its range: R. c. calendula, R. c. grinnelli, R. c. obscurus, and R. c. cineraceus.
Population and Conservation Status
Ruby-crowned Kinglets have an extremely large range across North America. Partners in Flight estimates a global breeding population of 67 million birds. Their numbers are steadily increasing throughout their range.
Due to their huge numbers, the Ruby-crowned Kinglet is evaluated as a species of Least Concern by the IUCN Red List. They face no imminent threats or major population declines.
Conclusion
In summary, key identifying characteristics of the Ruby-crowned Kinglet include its tiny size, lime-green coloration, flashy orange crown patch, and active foraging. This common songbird breeds in northern forests and migrates to southern U.S. states and Central America for winter.
With abundance populations across North America, the Ruby-crowned Kinglet remains a species of Least Concern for conservation. Birders can find this energetic little songbird fluttering actively through both coniferous and deciduous woodlands.