- 3.5–4.3 in
- 6.3–7.1 in
- 0.2–0.4 oz
- Smaller than a chickadee or warbler; about the same size as a Golden-crowned Kinglet.
- Roitelet à couronne rubis (French)
- Reyezuelo de Rojo, Reyezuelo Monicolorado, Reyezuelo de Coronilla Colorado, Reyezuelo (Spanish)
- The Ruby-crowned Kinglet is a tiny bird that lays a very large clutch of eggs—there can be up to 12 in a single nest. Although the eggs themselves weigh only about a fiftieth of an ounce, an entire clutch can weigh as much as the female herself.
- Ruby-crowned Kinglets seem nervous as they flit through the foliage, flicking their wings nearly constantly. Keeping an eye out for this habit can be a useful aid to identifying kinglets.
- Metabolic studies on Ruby-crowned Kinglets suggest that these tiny birds use only about 10 calories (technically, kilocalories) per day.
- The oldest known Ruby-crowned Kinglet was at least 4 years 7 months old. It was a banded individual captured (and re-released) at a California banding station in 2007.
Though Ruby-Crowned Kinglets are most often found in spruce-fir forests in the northwestern United States and Canada, they also live in mixed woods, in isolated trees in meadows, in coniferous and deciduous forests, in mountain-shrub habitat, or in floodplain forests of oak, pine, spruce or aspen. These birds nest high in trees, and so prefer older, taller, and denser stands to younger ones.
Ruby-Crowned Kinglets prey on spiders, pseudoscorpions, and many types of insects, including aphids, wasps, ants, and bark beetles. Kinglets usually forage in high tree foliage, hovering and pecking in order to glean insects from the surface of leaves and branches. These birds also eat a small amount of seeds and fruit, from poison-oak berries to the pulp of dogwood berries.
- Clutch Size
- 5–12 eggs
- Number of Broods
- 1 broods
- Egg Length
- 0.5–0.6 in
- Egg Width
- 0.4–0.5 in
- Incubation Period
- 12–14 days
- Nestling Period
- 16–18 days
- Egg Description
- Drab white spotted with red-brown around large end.
- Condition at Hatching
- Helpless and completely naked, without any down.
It takes Ruby-Crowned Kinglet females five days to build their nests, making trips every five minutes or so to gather materials: grasses, feathers, mosses, spiderwebs and cocoon silk for the outer structure, fine plant material and fur for the inner lining. When completed, the globe-shaped nest is 4 inches wide and 5-6 inches deep, and requires regular maintenance to keep it from disintegrating. Inside, it's about 3 inches across and 2 inches deep. The nest is elastic enough that it can stretch as the brood grows.
Ruby-Crowned Kinglets make their nests in trees, occasionally as high up as 100 feet. Females choose a nest site near the tree trunk or suspended from small twigs and branchlets. Because of the nest site's height and often remote location, not much is known about kinglet nesting habits. Their nest sites, chosen by the females, are protected and often hidden by overhanging foliage.
Breeding pairs of Ruby-Crowned Kinglets stay together for two months, until their chicks fledge. Ruby-Crowned Kinglets use their long, bubbly, and amazingly loud songs to establish territories; this is more energy efficient than chasing and less dangerous than fighting. They can be recognized by a constant flicking of their wings.
Ruby-crowned Kinglets are common and their numbers are stable, according to the North American Breeding Bird Survey. The global breeding population is an estimated 90 million, according to Partners in Flight, with 72 percent of these spending part of the year in the U.S., 81 percent breeding in Canada, and 26 percent wintering in Mexico. They are a 6 out of 20 on the Continental Concern Score and are not on the 2012 Watch List. Kinglets seem to handle human disturbance and habitat fragmentation fairly well, though logging and wildfire may reduce their numbers. Their wide use of habitats in winter helps them tolerate human disturbances.
Short-distance migrant. Ruby-crowned Kinglets breed across far northern North America as well as the western mountains. Most migrate to the southern and southwestern United States and Mexico for the winter—but some mountain populations in the West simply move to lower elevations during the cold months.
Find This Bird
Ruby-crowned Kinglets are fast-moving but quiet little birds that you might overlook at first. If you’re scanning roadside bushes or watching a flock of warblers, you might see one dart into view and keep moving through the foliage, almost too fast for you to keep up. Keep an eye out for their characteristic habit of wing-flicking. Don’t rely on seeing this bird’s ruby crown—it’s often kept completely hidden. But do listen for both the male’s loud song (often given during migration as well as in the breeding season) and for the double-noted call, which can be distinctive once you learn it. In much of the U.S., look for this species in the winter or on migration, when they are widespread and quite common. During summer you’ll need to be in northern North America or the western mountains to see them.