Eastern Bluebird

## Description

The eastern bluebird (Sialia sialis ) is a small North American migratory thrush found in open woodlands, farmlands, and orchards.

The bright-blue breeding plumage of the male, easily observed on a wire or open perch, makes this species a favorite of birders. The male's call includes sometimes soft warbles of jeew or chir-wi, or the melodious song chiti WEEW wewidoo.It is the state bird of Missouri and New York.

## Appearance

Eastern bluebirds are beautiful, well-known, popular songbirds that live in eastern North America. These little birds are easily recognized by the male's bright royal blue upper plumage, chest of the reddish-brown and white abdomen. The female is duller in color than the male, with grayer upper parts; but with an elegant look from the blue tinges to her wings. These bluebirds are the most common of the three bluebird species. Today many of the eastern bluebirds in North America nest in birdhouses intended for them on "bluebird trails." When not nesting, these birds fly in small flocks around the countryside.

## Distribution

Eastern bluebirds are found in eastern North America and Central America, from southern Canada to Nicaragua. There is a number living in Bermuda. Eastern bluebirds are partial migrants; the more northerly populations tend to move southwards in winter, with those further south generally remaining resident year-round in the breeding areas. These birds prefer to live in open country around trees, but with little understory and sparse ground cover. Original habitats probably included open, frequently burned pine savannas, beaver ponds, mature but open woods, and forest openings. Today, they are most common along pastures, agricultural fields, suburban parks, backyards, and even golf courses.

## Behavior

Eastern bluebirds are diurnal and very social birds. They sometimes gather in flocks numbering one hundred or more. They are also territorial and will defend a feeding and nesting territory around their nest site during the breeding season, as well as, in winter, a feeding territory. When feeding, they often fly from their perch to the ground in order to catch a prey item such as an insect. Sometimes they use gleaning or flycatching. Eastern bluebirds have good eyesight and they are able to locate small food items from distances of more than 100 feet. They fly quite low to the ground with a fast and irregular wing beat. Territorial males chase each other at fast speeds, sometimes fighting with their feet, plucking at feathers with their bills, and hitting their opponents with their wings.

## Diet

Eastern bluebirds are carnivores (insectivores, vermivores); they eat insects and their larvae, including caterpillars, butterflies, moths, and grasshoppers. They also eat berries, earthworms, spiders, snails, and other invertebrates.

## Reproduction

Eastern bluebirds are monogamous, and a pair may remain together for more than just one season. Breeding usually occurs in April, though the season runs from February to September. A male will display at a potential nest site to attract a female, bringing nest material, going in and out of a suitable hole, then perching above it, waving his wings. He will select several nest sites, and the female may begin to build nests in different sites before choosing one and completing a nest. The cup-shaped nest is often located in an old woodpecker hole, a dead tree, or a nest box. It is made from dry grasses, weed stems, and rootlets. 3 to 5 white or sky blue eggs are laid, and incubation is by the female, for around 12 to 14 days. The altricial chicks hatch within one or two days of one another and their mother broods them at this time. Both parents tend to their young, brooding them at night if it is cold. The chicks fledge at around 16 to 22 days and are dependent on their parents for a further 3 to 4 weeks. They become reproductively mature at one year of age.

## Population

### Population threats

Eastern bluebird numbers fell in the early 20th century as European starlings, house sparrows, and other aggressive introduced species caused available nest holes to be increasingly difficult for the bluebirds to use. Other potential threats include increased use of pesticides as well as the use of metal fence posts in preference to wooden ones, decreasing the possibility of nesting holes in rotting posts.

### Population number

According to the IUCN Red List resource, the total population size of the Eastern bluebird is 23 million mature individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are increasing.

### Ecological niche

Being insectivorous, these birds affect insect populations in their range.

## Fun Facts

The Eastern bluebird is the official state bird for Missouri and New York in the USA.

The song of these birds is one of its most distinguishing characteristics. They use different songs for mating and territoriality, as well as other purposes. The most common bluebird call sounds like “chur lee” or “chir wi”. When repeated a number of times, the call sounds like the words “truly” or “purity”.

A male of this species may sing as many as 1,000 songs an hour in his attempt to attract a mate.

If faced by a predator, an Eastern bluebird will flick its wings and warble, and a male will make song-like warning cries.