The Ruby-crowned Kinglet is a tiny, active songbird that occurs throughout much of Arizona, especially in winter and during migration. Measuring only about 3.5–4.3 inches in length and weighing a mere 0.2–0.3 ounces, it is among the smallest birds regularly found in the state. Males show a brilliant ruby-red crown patch that is usually hidden and only flashed when agitated or in display, while both sexes are olive-green overall with a pale eye ring and constant flicking of their wings, which makes them easy to recognize.
In Arizona, Ruby-crowned Kinglets are widespread during the cooler months, inhabiting a variety of wooded habitats including riparian corridors, pinyon-juniper woodlands, oak-pine canyons, and urban parks. They are common winter residents across much of the state, descending from northern breeding grounds in Canada and the western United States. A smaller number also breed in higher-elevation forests of northern and eastern Arizona, particularly in spruce-fir and mixed conifer zones of the “Sky Island” mountain ranges.
The species feeds primarily on insects, spiders, and other small invertebrates, gleaning them from foliage with quick, darting movements. It will also take berries and sap during leaner months. The Ruby-crowned Kinglet is noted for its surprisingly loud, complex song, which carries far beyond what its small size suggests, and is especially conspicuous during spring migration and in breeding areas.
