Ruby-crowned Kinglet    Regulus calendula

Migratory Status: Short-distance migrant

PIF Population Estimate: 70 000 000

Percent of western hemisphere population breeding in boreal forest: 68%

BAM Effective Detection Radius (m) : 84.88

PIF Maximum Detection Distance (m) : 125

Canadian BBS Population trend: -1.3 (-2.1 to -0.6)

Life History

The Ruby-crowned Kinglet is a nondescript, tiny but active songbird of coniferous forests. Males and females look similar; greenish-gray above, with pale gray-green underparts. They are long-legged and short-tailed in appearance, and have two bold whitish wing-bars and a white, broken eye-ring. The male has a scarlet crown patch, usually only noticed when the bird is singing or otherwise excited. Juveniles have the same plumage as females.

Ruby-crowned Kinglets have an extensive range in the boreal forest, breeding across the continent from Alaska to Newfoundland. They also nest in bogs and montane regions as far south as New Mexico. The preferred breeding habitat is black spruce (Picea mariana) and black spruce/tamarack (Larix larcina) muskeg, but they will also use other moist, open conifer forests. Territorial densities are highest in muskeg habitats, with an average territory size of 3 ha in some areas.

During migration, Ruby-crowned Kinglets inhabit forest edges, thickets and riparian areas. They typically forage and travel relatively close to the ground, often in small flocks. By late fall, most Ruby-crowned Kinglets have left Canada to winter in the southern United States and Mexico, although some remain in southwestern British Columbia and along the Pacific coast of the United States. During migration and on the wintering grounds, Ruby-crowned Kinglets frequently form mixed flocks, joining with Golden-crowned Kinglets (Regulus satrapa) and other warbler and vireo species.

Both males and females sing, with the male having a more complete repertoire. The full song consists of a series of high “tee” or “zee” notes, followed by a few emphatic “chu” notes, and finished up with a rolling “chi-da-leet, chi-da-leet, chi-da-leet”. Partial songs are common, with shortened versions often heard in winter or during migration. The song is very loud, and carries a great distance; the “chi-da-leet” song can sometimes be detected over a kilometre away. During the breeding season, males frequently sing from the top of a spruce or tamarack, while the females tend to sing quietly while on or adjacent to the nest. Calls are heard year-round, which are a simple two-syllable “ji-dit”.

Reference(s)

Swanson, D. L., J. L. Ingold and G. E. Wallace. 2008. Ruby-crowned Kinglet (Regulus calendula), The Birds of North America Online, . A. Poole, Ed. Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of North America Online database: http://bna.birds.cornell.edu/bna/species/119