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Nesting Season: Crows.net Project.

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Nesting Season for American Crows

Razzle the crow collects nest lining material. Photo by Renee Thompson.

As the buds begin to swell and spring-like days come more frequently, nesting activity may start in warmer parts of the continent. Crows may be seen carrying nesting material, preening each other, being involved in brief "flurry fights" over territory or dominance, and may be heard making various vocalizations other than the familiar cawing. Clicking or rattling sounds, soft "coo-ah" noises and a variety of others seem to be associated with mating activities, though what their actual role is remains unclear. The timing of nest building and egg laying varies with location and climatic conditions , as well as with the particular temperature range in any given year. Generally crows are among the earliest birds to begin the nesting process, so if you see any other birds involved in nest building or sitting on nests, you can be pretty sure that your local crows are at least as far along in the process.

During the first few days of nesting, the female may be quite noisy, vocalizing short somewhat raucous calls frequently, often several times a minute for long periods of time. Later on, after eggs are laid, the mating pair becomes much quieter and more secretive, so as to not give away the nest location to potential predators. If suddenly the crow noises in your neighborhood diminish dramatically and if crows come silently to your feeding station, without the usual discussion over whether its safe to dine, then you can be relatively certain that there are eggs or young birds in the nest.

NESTING SEASON IS IN FULL SWING. If you observe any nesting season activity such as, nest building, eggs, nestlings, or fledgling crows, please send us a report giving your location, the date of the observation, and just what you have observed. We will post it on the Nesting season map below.

MAP OF CROW NEST BUILDING, NESTING, AND FLEDGING Yellow pointers show 2011 data. Blue pointers show 2010 data. Drag map to show locations not visible, or click below the map for a larger version.


View American crow: Fledging Dates in a larger map

NESTS:

One of the more common misconceptions about birds is that they actually live in nests like humans live in houses or, at the very least, sleep in them at night. In reality, birds use nests only to incubate eggs and to hold the young birds until they are ready, or almost read to fly (fledge). After the young have fledged, the nest is generally abandoned, either permanently or until the next breeding period.

Click here to view a typical crows nest.

Crows nests are quite large, measuring up to two feet or more in diameter and nine or more inches high. The outer portion of the nest, which comprises the major portion of the structure, is composed primarily of dead branches, although many other materials may be used if sufficient branches of the proper size are not available. Within this large outer structure is an interior “cup” composed of softer materials in which the eggs are laid and incubated and the young reared. This interior cup is much smaller than the outer nest with a diameter of six or seven inches and a depth of four or five inches.

Both male and female crows work in constructing the nest sometimes aided by one or more “helpers”, generally their offspring from previous years. When possible, nests are located well hidden in crotches high up in tall trees. If no suitable trees are available, crows may nest in shrubs, man-made structures, and rarely on the ground. Crows tend to build new nests each year, seldom reusing a nest from a previous year. The new nests, however, will generally be located close to the old nests within the area claimed as the territory of a particular pair, or family, of crows.

Crow eggs. Photo by Renee Thompson.

EGGS:

Crows generally lay from 3 to 7 eggs, with 4 or 5 being the most common number. The coloration and pigment pattern of the eggs can vary widely even within a single clutch with eggs being bluish-green to pale olive and variously marked with brown and gray and can vary from almost unmarked sky blue to very heavily blotched or spotted dark green. In size they average about 1.15 inches (29.13 mm) by 1.6 inches (41.40 mm) and about .0.6 ounce (17.0 g).

Eggs may be laid as soon as the nest is finished but some crows may wait two weeks or more between completion of the nest and laying of the first egg. Eggs are usually laid one a day, generally in the late morning, with occasionally a day or two skipped between eggs. The female will generally begin incubation of the eggs before all of them have been laid, usually beginning to sit continuously after the laying of the third egg. This results in an interval between the hatching of the first and last bird of about 3 days. The female commonly is the only one of the pair that incubates the eggs, which hatch after about 18 days.

Nestling. Photo by Renee Thompson.

NESTLINGS:

When crows hatch they are blind and helpless covered with a small amount of down, and weigh a bit over an half ounce (15.5 g). The mother will brood the young birds more or less continuously for up to two weeks, with rare breaks to collect food. After two weeks the breaks become more frequent and of longer duration until, somewhere between 30 and 40 days after hatching the young are ready to leave the nest. While the female is brooding the young the male, and frequently one or more helper crows, will collect food and carry it to the nest in their throats and/or “sublingual pouches”. They may feed the young birds directly or pass some of the food to the brooding female who may eat some of it or pass it along to the nestlings.

FLEDGLINGS:

When young crows leave the nest, their flight feathers are not fully developed and they may not be capable of taking to the air for at least several more days. Ideally they will hop about in the nest tree while they gain the full ability to fly, but sometimes they fall to the earth where they may spend several days on the ground or in low vegetation . Even when they are on the ground, the parent birds will look after them and feed them if possible and as long as they are not taken by predators or “rescued” by helpful humans, they will eventually rejoin their family.

Young crows will be completely dependent upon their parents for food for a couple of weeks after leaving the nest and it may be three or four months before they are completely able to obtain all of their food themselves.

Click here to view a fledgling American crow.

The fledgling in the photo shows the characteristics that distinguish these young birds from adult crows and from other species. The fledgling differs from an adult crow in that it has yellow coloration on its bill, eyes that appear gray or blue rather than dark brown, and poorly developed tail feathers. Its large size, along with its black legs and feet, distinguish it from any species other than the raven or other varieties of crow.

(This section will be added to on a continuing basis. Your comments and suggestions are welcomed. Other parts of the site are also under construction. This site will continually expand as the Crows.net Project grows.)

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