Common Grackle Life History

Habitat

Habitat Open WoodlandsCommon Grackles do well in human landscapes, using scattered trees for nesting and open ground for foraging. Typical natural habitats include open woodland, forest edge, grassland, meadows, swamps, marshes, and palmetto hammocks. They are also very common near agricultural fields and feedlots, suburbs, city parks, cemeteries, pine plantations, and hedgerows. Unbroken tracts of forest are the only places where you are unlikely to find Common Grackles.Back to top

Food

Food OmnivoreCommon Grackles eat mostly seeds, particularly agricultural grains such as corn and rice. Other seeds include sunflower seeds, acorns, tree seeds such as sweetgum, wild and cultivated fruits, and garbage. In summer, one-quarter or more of a grackle’s diet may be animals, including beetles, grasshoppers, caterpillars, spiders, crustaceans, mollusks, fish, frogs, salamanders, mice, and other birds.Back to top

Nesting

Nest Placement

Nest TreeThe female chooses the nest site, with the male sometimes following along as she surveys. After beginning to build, females often seem to change their minds and select another site. Typically the nest is high in a coniferous tree between two vertical limbs or on a horizontal branch (although they’ve been recorded as low as 8 inches off the ground and in deciduous vegetation, cattails and other sites). Nests are often built near water. Rarely, Common Grackles nest in unusual places such as birdhouses, woodpecker holes, cliff crevices, barns, and still-occupied nests of Osprey and Great Blue Herons.

Nest Description

Females typically build the nest, with males sometimes helping or making repairs. The nest can take as little as a week to as long as six weeks to finish. It’s a bulky cup made of twig, leaves, and grasses along with bits of paper, string, cloth, corn husks and other incidental materials. The female reinforces the nest cup with mud and then lines it with fine grasses and horse hair. The finished nest is 6-9 inches across, with an inside diameter of 3-5 inches and a depth of 3-9 inches.

Nesting Facts
Clutch Size:1-7 eggs
Number of Broods:1-2 broods
Egg Length:1.0-1.3 in (2.5-3.3 cm)
Egg Width:0.8-0.9 in (1.9-2.3 cm)
Incubation Period:11-15 days
Nestling Period:10-17 days
Egg Description:Light blue, pearl gray, white, or dark brown, usually spotted with brown.
Condition at Hatching:Blind and naked except for sparse brownish down; poorly coordinated, weighing just under a quarter-ounce.
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Behavior

Behavior Ground ForagerCommon Grackles are large, noisy, and gregarious birds that often flock with other blackbirds, cowbirds, and starlings, especially in winter. At feeders they tower over other birds and push them aside to get at food. Grackles typically forage on the ground and roost high in trees or on power lines. Common Grackles sometimes nest in loose colonies of up to 200 pairs, showing little territoriality except in the immediate area of the nest. In spring when birds are pairing, you may see three kinds of playful chases: first, a group of males will fly after a slow-flying female; second, a single male will chase a female at high speed; and third, a male and female will fly slowly and conspicuously alongside each other. In normal flight, grackles fly in a direct path on stiff wingbeats.Back to top

Conservation

Conservation Common Bird in Steep DeclineCommon Grackles are abundant and widespread, though populations declined by almost 2% per year between 1966 and 2014, resulting in a cumulative decline of 58%, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 61 million, with 100% spending part of the year in the U.S., and 10% breeding in Canada. They rate an 8 out of 20 on the Continental Concern Score and the 2014 State of the Birds Report lists them as a Common Bird in Steep Decline.Back to top

Backyard Tips

This species often comes to bird feeders. Find out more about what this bird likes to eat and what feeder is best by using the Project FeederWatch Common Feeder Birds bird list.

During migration, set up bird feeders in your yard with a variety of mixed grain and seeds. Spreading grain or seed on the ground helps, as this is where Common Grackles prefer to feed – and if they come to the ground they may let smaller birds continue to use the feeders. Bear in mind that too much grain scattered on the ground can attract rodents, so it's best to sprinkle just as much as the birds are likely to eat at any one time.

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Credits

Ehrlich, P. R., D. S. Dobkin and D. Wheye. 1988. The birder's handbook. A Field Guide to the natural history of North American birds, including all species that regularly breed north of Mexico. New York: Simon and Schuster, Inc.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

North American Bird Conservation Initiative. 2014. The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.

Partners in Flight. 2017. Avian Conservation Assessment Database. 2017.

Peer, Brian D. and Eric K. Bollinger. 1997. Common Grackle (Quiscalus quiscula), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center 2014b. Available from http://www.mbr-pwrc.usgs.gov/bbs/.

Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

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