American Robin and Eastern Bluebird by Genkicoll

American Robin

The American Robin (Turdus migratorius, also called North American Robin) is a migratory songbird of the thrush family. It is named after the European Robin because of the male's bright red breast, though the two species are not closely related. The American Robin is widely distributed throughout North America, wintering south of Canada from Florida to central Mexico and along the Pacific Coast. It is the state bird of Connecticut, Michigan and Wisconsin. It has seven subspecies, but only T. m. confinis in the southwest is particularly distinctive, with pale gray-brown underparts.

The American Robin is active mostly during the day and assembles in large flocks at night. Its diet consists of invertebrates (such as beetle grubs and caterpillars), fruits and berries. It is one of the first bird species to lay eggs, beginning to breed shortly after returning to its summer range from its winter range. Its nest consists of long coarse grass, twigs, paper, and feathers, and is smeared with mud and often cushioned with grass or other soft materials. It is among the first birds to sing at dawn, and its song consists of several discrete units that are repeated.

The adult robin is preyed upon by hawks, cats and larger snakes, but when feeding in flocks it is able to be vigilant and watch other birds for reactions to predators. Brood parasitism by the Brown-headed Cowbird occurs, but is rare because the robin usually rejects the cowbird eggs.

Description

The nominate subspecies of the American Robin is 23–28 centimeters (10–11 in) long with a wingspan ranging from 31–41 centimeters (12.2–16 in), and averages about 77 grams (2.7 oz) in weight. The head varies from jet black to gray, with white eye arcs and white supercilia. The throat is white with black streaks, and the belly and undertail coverts are white. The Robin has a brown back and a reddish-orange breast, varying from a rich red maroon to peachy orange. The bill is mainly yellow with a variably dark tip, the dusky area becoming more extensive in winter, and the legs and feet are brown.

The sexes are similar, but the female tends to be duller than the male, with a brown tint to the head, brown upperparts and less bright underparts. However, some birds cannot be safely sexed on plumage alone. The juvenile is paler in color than the adult male and has dark spots on its breast, and whitish wing coverts. First-year birds are not easily distinguishable from adults, but they tend to be duller, and a small percentage retains a few juvenile wing coverts or other feathers.

Distribution and habitat

This bird breeds throughout most of North America, from Alaska and Canada southward to northern Florida and Mexico. While Robins occasionally overwinter in the northern part of the United States and southern Canada, most migrate to winter south of Canada from Florida and the Gulf Coast to central Mexico, as well as along the Pacific Coast. Most depart south by the end of August and begin to return north in February and March (exact dates vary with latitude and climate).

Eastern Bluebird

The Eastern Bluebird, Sialia sialis, is a medium-sized thrush found in open woodlands, farmlands and orchards, and most recently can be spotted in surburban areas. It is the state bird of Missouri and New York.

Adults have a white belly. Adult males are bright blue on top and have a reddish brown throat and breast. Adult females have lighter blue wings and tail, a brownish throat and breast and a grey crown and back. Eastern Bluebirds are found east of the Rockies, southern Canada to the Gulf States and southeastern Arizona to Nicaragua.

The bright blue breeding plumage of the male, easily observed on a wire or open perch, fluttering down to the mowed grass to capture a grasshopper, cricket or beetle 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 (Sibley, 2000).

Conservation status

The population of the Eastern Bluebird declined seriously enough in the past century to reach critical status by the mid-1900s. The decline was due to:

1. Habitat destruction (loss of fields and nesting cavities in split-rail fences; clearing of dead trees)

2. Pesticide use

3. Nest predation by House Sparrows and European Starlings; both of which are non-native, introduced species.

The species was rescued by a network of birding enthusiasts who erected nesting boxes for Bluebirds, with close monitoring necessary to prevent House Sparrows from nesting in them. They remain thoughtful of conservation, however, with competition still prevalent from other species (e.g. Tree Swallows, which are a native species and which also nest in cavities) and in certain states of the US they can still be difficult to spot. It is worth noting that due to the increase in their numbers in the past few decades, they are not protected under CITES or U.S. Endangered Species Act.

The Bluebird is the state bird of Missouri and New York.

The Eastern Bluebird is also found in Bermuda, where the population may constitute a sub-species. Bermuda Bluebirds have become endangered by the loss of 8 million Bermuda cedar trees in the 1940s, and by nest predation from introduced Sparrows, Starlings, and Kiskadees. Kiskadees, introduced in 1957, have also contributed to declines of other species, such as the Cardinal and the Catbird. In 1987, Hurricane Emily destroyed much of Bermuda's forest habitat, adversely affecting the Bluebird and other tree-dependent species.

Food

Approximately two-thirds of the diet of an adult eastern bluebird consists of insects and other invertebrates. The remainder of the bird's diet is made up of wild fruits. Favored insect foods include grasshoppers, crickets, katydids, and beetles. Other food items include earthworms, spiders, millipedes, centipedes, sow bugs, and snails. Fruits are especially important when insects are scarce in the winter months. Some preferred winter food sources include dogwood, hawthorn, wild grape, and sumac and hackberry seeds. Supplemental fruits eaten include blackberries, bayberries, fruit of honeysuckle, Virginia creeper, Eastern Juniper, and pokeberries. Bluebirds feed by perching on a high point, such as a branch or fence post, and swooping down to catch insects on or near the ground. The availability of a winter food source will often determine whether or not a bird will migrate. If bluebirds do remain in a region for the winter, they will group and seek cover in heavy thickets, orchards, or other areas in which adequate food and cover resources are available.

Source: Wikipedia

Updated 2010-11-17

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