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Great-tailed Grackle Life History


ScrubWhere people have gone, Great-tailed Grackles have followed: you can find them in both agricultural and urban settings from sea level to 7,500 feet that provide open foraging areas, a water source, and trees or hedgerows. In rural areas, look for grackles pecking for seeds in feedlots, farmyards, and newly planted fields, and following tractors to feed on flying insects and exposed worms. In town, grackles forage in parks, neighborhood lawns, and at dumps. More natural habitats include chaparral and second-growth forest. You’re unlikely to see them in dense forests, or in deserts or prairie habitats that lack access to water. Back to top


InsectsGreat-tailed Grackles eat plant material year round, including grains such as corn, sorghum, and oats as well as fruits. In summer and early fall, animals make up half or more of their diet, with females eating up to 80% animal matter. Prey includes grasshoppers, beetles, spiders, bees, wasps, snails, worms, slugs, and moths. Grackles also feed on tadpoles, frogs, lizards, snakes, fish, and small mammals such as mice and shrews, as well as bird eggs and nestlings. Back to top


Nest Placement

TreeFemales choose the nest site, picking a place as high as possible in a tree or shrub with several upright twigs for anchoring the nest, and water and foraging areas nearby. Nest heights may reach more than 60 feet off the ground. Where trees aren’t available, females choose sites in rushes, cattails, and other marsh vegetation, or on human-made structures such as duck blinds and telephone poles. She may abandon her initial nesting attempt in favor of a new site, or a new social mate.

Nest Description

Females weave a bulky cup of grasses, bark strips, weeds, rushes, and other plants, anchoring the rim to upright twigs or small branches. Weaving material can include plastic strips and bags, ribbons, flagging tape, feathers, and string. She lines the nest cup with mud or cow dung and adds a soft inner layer of fine grasses. Building the nest can take 5 to 17 days, with the male sometimes guarding the site from other females trying to pilfer nesting material. The finished nest is 4 to 13 inches deep and 7.5 inches across, with a cup measuring 2 to 4 inches deep and 4 inches wide.

Nesting Facts

Clutch Size:1-5 eggs
Number of Broods:1-2 broods
Egg Length:1.1-1.5 in (2.7-3.7 cm)
Egg Width:0.8-0.9 in (2.1-2.4 cm)
Incubation Period:13-14 days
Nestling Period:20-23 days
Egg Description:Bright blue to pale bluish gray, marked with dark brown to black swirls and splotches.
Condition at Hatching:Blind and mostly naked, with pale, salmon-colored skin and long, sparse gray down.
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Ground ForagerGreat-tailed Grackles are loud, social birds that can form flocks numbering in the tens of thousands. Each morning small groups disperse to feed in open fields and urban areas, often foraging with cowbirds and other blackbirds, then return to roosting sites at dusk. This evening routine includes a nonstop cacophony of whistles, squeals, and gunfire-like rattling as birds jostle for preferred positions. In early spring, males establish breeding territories in one or more trees, which they fiercely defend against other males. Territorial “ruff-out” displays of erected feathers, fanned tail, and bill held skyward may erupt into wrestling matches, with competing males locking talons and rolling on the ground. Dominant males mate with one or more “social mates” within their territory and may try and mate with other females, while females have a single social mate but may copulate with other males. Females brood and feed the chicks, which the male defends from intruders. Back to top


Low Concern

Great-tailed Grackles thrive in human-altered landscapes and have spread rapidly in areas of irrigated agriculture and urban development. Populations were stable or slightly increasing across their range between 1966 and 2019, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 30 million and rates them 5 out of 20 on the Continental Concern Score. In the western U.S., Great-tailed Grackle range has expanded more than any other native bird, and these birds are often treated as pests for their habit of eating young corn and sorghum sprouts, feeding in grapefruit and other citrus groves, and raiding the nests of White-winged Doves. Grain and citrus growers shoot and haze birds or use chemical repellents.

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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. Simon and Schuster Inc., New York, NY, USA.

Johnson, Kristine and Brian D. Peer. (2001). Great-tailed Grackle (Quiscalus mexicanus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. (2020). Longevity records of North American birds. Version 2020. Patuxent Wildlife Research Center, Bird Banding Laboratory 2020.

Partners in Flight. (2020). Avian Conservation Assessment Database, version 2020.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2019). The North American Breeding Bird Survey, Results and Analysis 1966–2019. Version 2.07.2019. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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