A small, colourful thrush, the eastern bluebird (Sialia sialis) is named for its bright blue plumage and its distribution in eastern parts of North America. One of the continent’s most easily recognised birds, the male eastern bluebird is a vivid blue on the back, tail, wings and head, with a contrasting red-orange throat, breast and flanks and a white belly. The female eastern bluebird is duller than the male, with greyer upperparts, a bluish tail and wings, and paler orange on the underparts. As in the male, the belly and undertail are white. Both male and female eastern bluebirds have a large, rounded head, a plump body, a relatively short tail and legs, and a short black bill that is slightly notched at the tip. The legs, feet and eyes are black, and there is a thin white ring around the eye. Juvenile eastern bluebirds have dull, brownish upperparts with whitish spots, as well as white spots and streaks on the greyish-brown breast. The wings and tail are bluish, with juvenile males being brighter blue than juvenile females. The eastern bluebird only shows slight variations in size and appearance across its large range. Eightsubspecies are recognised, but the differences between them are relatively minor, and there is much overlap. The eastern bluebird is quite similar in appearance to the closely related western bluebird (Sialia mexicana) and mountain bluebird (Sialia currucoides), but the male western bluebird has chestnut shoulders and a blue rather than red-orange throat, while the male mountain bluebird is lighter blue and lacks a reddish breast. The females of these species can be harder to tell apart. The most common call of the eastern bluebird is a soft, low-pitched, melodious ‘tu-a-wee’ or ‘tura-lee’, while its song is a fairly low, short, varied series of warbles and whistles. This song is usually given by the male from a high perch or in flight, although the female may sometimes also sing if a predator is spotted near the nest. The eastern bluebird typically hunts from a low perch, dropping down to the ground to capture prey, which it can spot from some distance away. Male eastern bluebirds attract a female by taking nesting material to a potential nest site, going in and out, and perching above it with waving wings. One of the main threats to the eastern bluebird has been competition for nesting cavities with introduced birds such as house sparrows and European starlings.