The Ruby-crowned Kinglet (Regulus calendula) is a very small songbird.

Adults are olive-grey on the upperparts with light underparts, with a thin black bill and a short tail. They have white wing bars and a white broken eye ring. The adult male has a red patch on his crown which is usually only visible when he is agitated (see photo).

Their breeding habitat is coniferous forests across Canada, Alaska, northern New England and the western United States. They nest in a well-concealed hanging cup suspended from a conifer branch and may lay as many as twelve eggs in a clutch.

The recent counting indicates that the Ruby-crowned kinglet population is on the rise. This is mainly due to discovery of less disturbed territory farther north. This allows more successful breeding.

These birds migrate to the southern United States and Mexico. Some birds are permanent residents in the west.

They forage actively in trees or shrubs, mainly eating small insects and spiders, some berries and tree sap. They may hover over a branch while feeding and sometimes fly out to catch insects in flight.

Their song is a melodious warble and fairly loud, but at least in winter habitat, the most common vocalization is a wren-like scolding "jdit", often repeated several times in close succession.