The glossy-iridescent Common Grackle is one of the more common and widespread birds nesting in Tennessee, and in winter it forms enormous flocks containing hundreds of thousands of individuals. It can be found in a variety of habitats from farmland and suburban areas to wetlands and forest edge. Common Grackles range over most of North America east of the Rockies, breeding into central Canada and wintering in the southeastern portion of the range.
Description: The male Common Grackle is an elegant, glossy, iridescent purple-black bird with a long, keel-shaped tail; the female is slightly smaller and duller. Both sexes look black at a distance and have pale eyes. The juvenile (June-September) is dull brown with dark brown eyes.
Weight: 4 oz
Voice: The song is a series of harsh, metallic notes resembling the squeak of a rusty hinge.
- All other blackbirds found in Tennessee are smaller with shorter tails and bills.
Habitat: Common Grackles are found in a variety of open areas with scattered trees, including open woodland, swamps, marshes, agricultural areas, urban residential areas, and parks.
Diet: Common Grackles are omnivorous, eating insects, minnows, frogs, eggs, berries, seeds, grain, acorns, and even small birds.
Nesting and reproduction: Males begin courtship activities in mid-March, but there is little territorial defense and birds nest as isolated pairs or in small loose colonies. Peak egg laying is in late April, and females raise one brood per season.
Clutch Size: Range from 3 to 7 eggs, with 4 to 5 eggs most common.
Incubation: The female incubates the eggs for about 13 days.
Fledging: Both adults feed the nestlings, which leave the nest in 12 to 14 days. Large flocks of adults and juveniles form by late June.
Nest: The female builds the large, bulky cup-nest from grasses and weed stems, and lines it with mud and fine grasses or hair. The nest is well concealed in dense deciduous or coniferous trees and shrubs, occasionally in tree cavities and nest boxes, and usually near water. Most Tennessee nests are high in red cedars or pines. The average height is 26 feet with a range of from 2 feet to 100 feet.
Status in Tennessee: The Common Grackle is one of the most numerous and widespread birds nesting in Tennessee, and is a locally common winter resident. Wintering flocks, sometimes with hundreds of thousands of birds, are most common in the western two-thirds of the state. Common Grackles in the state, as well as rangewide, are declining.
Dynamic map of Common Grackle eBird observations in Tennessee
Conservation: Common Grackles are one of the most significant agricultural pests today, causing millions of dollars in damage to sprouting corn. Lethal control measures are used in some areas to control numbers. Regardless, Common Grackles are still one of the most successful and widespread species in North America, with an estimated total population of 73,000,000 individuals. Because of a long-term declining population, they are a National Audubon Society Watch List Species (see link below).
- Male Common Grackles may abandon their mate before the young have fledged to pair and re-nest with another female.
- The oldest recorded Common Grackle was 23 years, one month old, although most don't live nearly that long. Only about half of all Common Grackles reach adulthood.
- Common Grackles eat other birds' eggs and nestlings, and occasionally kill and eat other adult birds, particularly adult House Sparrows.
- Common Grackles are very gregarious, even during the breeding season. Grackles that are not incubating often congregate at night in roosts that may contain thousands of individuals. Other species, including Red-winged Blackbirds, European Starlings, and Brown-headed Cowbirds can be found in these roosts.
- The Common Grackle commonly engages in anting, allowing ants to crawl on its body and secrete formic acid, possibly to rid the body of parasites. In addition to ants, it has been seen using walnut juice, lemons and limes, marigold blossoms, choke cherries, and mothballs in a similar fashion.
Obsolete English Names: blackbird, bronzed blackbird, purple crow blackbird, crow blackbird, bronzed grackle, purple grackle
Best places to see in Tennessee: Common Grackles are found nesting in every county in Tennessee. Winter populations are largest in the western two-thirds of the state.
For more information:
Nicholson, C. P. 1997. Atlas of Breeding Birds of Tennessee. Univ. of TN Press, Knoxville.
Peer, B. D. and E. K. Bollinger. 1997. Common Grackle (Quiscalus quiscula), The Birds of North America, No. 271 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists' Union, Washington, D.C.
Sibley, D. A. 2000. The Sibley Guide to Birds. A. A. Knopf, New York, NY.