Bird of the Month: Ruby-crowned Kinglet
Written by Andy McCormick
Andy McCormick, Volunteer and Former Board President of Eastside Audubon
Ruby-crowned Kinglet
Scientific Name: Regulus calendula
Length: 4.25”
Wingspan: 7.5”
Weight: 0.23 oz (6.5g)
AOU Alpha Code: RCKI
A vibrant tiny grayish bird of the forest, the Ruby-crowned Kinglet maintains a high activity level, lots of chatter, and a swift, erratic flight.
THE LITTLE KING
The Ruby-crowned Kinglet shares the genus Regulus, from the Latin for “little king,” with five other kinglets or crests: Golden-crowned Kinglet (R. satrapa) in North America, Goldcrest and Common Firecrest in Europe, Madeira Firecrest and Taiwan Firecrest in the Canary Islands and Taiwan, respectively. Its species name, calendula, Greek kalandros, a lark, derives from its beautiful song, most often heard in spring (Holloway). You can hear the bubbling warble, ji-dit calls, and contact notes of the Ruby-crowned Kinglet at the Macaulay Library.
HYPERACTIVE IN SPADES
Ruby-crowned Kinglets are active in the extreme hopping from one branch to another seeking insects and whatever is available. They are omnivorous and will eat berries in winter, seeds, and oozing sap at times. They forage at all levels and can often be seen in low bushes, especially in winter. This high level of activity makes these birds stand out despite their small size. They are smaller than the smallest warbler (Dunne).
The Ruby-crowned is a non-descript grayish-olive bird with a distinct broken (mainly at the top) teardrop-shaped eye ring. The ruby crown patch is infrequently seen but can be dramatically exposed when the bird is agitated or during courtship display (Alderfer). It has one clear white wing bar and a black bar across the wing below it. Compare this with the Hutton’s Vireo, which does not have such a bar. Also, during display the Ruby-crowned will flick its wings while tipping its body forward to expose the wing bars (Swanson, et al).
ALTITUDINAL MIGRANT
Ruby-crowned Kinglets migrate in October. The most northern breeding birds are complete migrants and winter in the western and southern United States and Mexico. However, many of these kinglets in the Pacific Northeast are altitudinal migrants and will occupy lower elevations within the breeding range (Swanson, et al). In migration and in winter the Ruby-crowned will often forage in mixed species flocks but will often be found alone (Dunne). Spring migration to northern latitudes and higher altitudes begins in April.
HIGH-ALTITUDE NESTER
The Ruby-crowned nests in conifers in the upper latitudes of North America and at high elevation in the western United States. It nests between 40 and 90 feet above the ground, or lower in the far north where trees are shorter. The female weaves a deep pensile (hanging) nest among twigs below a horizontal branch using a mixture of bark, lichen, spider webs, conifer needles and other materials, she lines it with feathers, plant down, and animal hair (Kaufman).
Between 7 and 8 eggs are deposited (up to 11 in the Pacific Northwest). The eggs are whitish and identical to those of the Golden-crowned Kinglet. Incubation lasts about two weeks. Both parents feed the nestlings, and the young will fledge in another two weeks (Kaufman).
The population of Ruby-crowned Kinglets is quite stable despite some losses during more severe winters. There may also be additional losses due to logging and wildfire, but the wide-ranging diet, use of a variety of habitats, and general all-around adaptability has protected the overall abundance of Ruby-crowned Kinglets.
Photo credit Mick Thompson.
References available upon request from amccormick@eastsideaudubon.org.