Monday, April 9, 2012

Common Grackle - Quiscalus quiscula

Common Grackles, or Crow Blackbirds as they are sometimes called, are blackbirds that look like they've been slightly stretched. They very common almost everywhere east of the Rockies Longer than most blackbirds, slimmer than most crows, Common Grackle males are very iridescent and have long tails with a distinct crease down the center. Generally, their heads, necks and breasts are glossy purplish-blue or bluish-green. However, common grackles in different parts of North America have somewhat different colored plumage.

In New England and in the West, the subspecies has a brassy bronze body coloration. Often called the Bronzed Grackle: it has a black head with blue-green iridescence. Sharply defined bronze back. Long, black tail with purplish iridescence. Called the Purple Grackle, this one has a black head, back, and sides with purple iridescence. May have iridescent barring on the back. Long, black tail with possible blue-green iridescence. Tail displays a longitudinal ridge or keel when in flight. Pale yellow eyes, though not always. Found from central Louisiana and Alabama north to southern New York and Connecticut, west of the Appalachian Mountains and in New England. East of the Allegheny Mountains, the body is purple, and in the southeast the feathers have a greenish hue.

Females are not as iridescent or as colorful, and their tails are not as distinctive, nor do they keel their tails much.
The iridescence of the head is different from that of the body, and changes abruptly behind the neck and breast; this applies to all forms of common grackle. The central feathers of the long, rounded tail are often depressed, so that the tail is displayed in flight with a deeply keeled V-shape, especially with breeding males in flight. Common Grackles taller, with long, strong legs and longer tailed than a typical blackbird, with a longer, and more tapered bill; bill and legs are black.

Grackles walk around lawns and fields on their long legs or gather in noisy groups high in trees, typically evergreens. They eat many crops (notably corn) and nearly anything else as well, including garbage. In flight their long tails trail behind them, sometimes folded down the middle into a shallow V shape, especially during breeding time. The adult female, beyond being smaller, is usually less iridescent; her tail in particular is shorter, and unlike the males, does not keel in flight. The juvenile is brown with dark brown eyes and faintly streaked on breast. These are one of the earliest passerine migrants in spring.

Common Grackles are large, lanky blackbirds with long legs and long tails. The head is flat and the bill is longer than in most blackbirds, with the hint of a downward curve. In flight, the wings appear short in comparison to the tail. Males are slightly larger than females.

Sized for Both Sexes:
  • Length: 11–13.4 inches
  • Wingspan: 14.2–18.1 inches
  • Weight: 2.6–5 ounces
  • Relative Size: Larger than a Red-winged Blackbird; about the same size as a Mourning Dove, though its long tail makes it appear larger.
Color Pattern
Common Grackles appear black from a distance, but up close their glossy purple heads contrast with bronzy-iridescent bodies. A bright golden eye gives grackles an intent expression. Females are slightly less glossy than males. Young birds are dark brown with a dark eye. As you know, there are many Leucistic birds; this is a Leucistic Common Grackle, below. Click the tag 'Leucistic' (at the end of this article) for more information.

Their diet consists of a wide variety of animal and vegetable food, including insects and invertebrates but also insects, crustaceans, earthworms, frogs, and small rodents and occasional eggs and nestlings. In rare instances, Common Grackles will attack and eat small birds and lizards, and in coastal areas they forage at the tide line for small invertebrates, even wading into the water to capture live fish. During the winter and migration months, their diet shifts to plant food, such as seeds and waste grain. Because of their predilection for agricultural grain and seeds, especially corn, Common Grackles have earned a reputation as a significant pest in certain areas of North America. The omnivorous grackles feed in farm fields, pastures, and suburban lawns by walking, rather than hopping, and they act aggressively toward, even stealing food from, other ground-foraging birds such as robins.
Sharp-shinned Hawks, Great Horned Owls and Red-tailed Eagles are predators of Grackles, not to forget predators of all birds; cats and dogs, skunks, raccoons, snakes and people.


The Lone Pine Field Guide to Birds describes the Common Grackle as a "poor but spirited singer who, despite his lack of musical talent, remains smug and proud, posing with his bill held high". Their call is a loud chuck, while their song is short creaky koguba-leek. Call: a loud and deep chuck. Song: a mechanical, squeaky readle-eak. Variety of whistles, clucks, and hissing notes. Both sexes sing.

Cool Facts

  • Those raggedy figures out in cornfields may be called scare-crows, but grackles are the #1 threat to corn. They eat ripening corn as well as corn sprouts, and their habit of foraging in big flocks means they have a multimillion dollar impact. Some people have tried to reduce their effects by spraying a foul-tasting chemical on corn sprouts or by culling grackles at
    their roosts.
  • Common Grackles are resourceful foragers. They sometimes follow plows to catch invertebrates and mice, wade into water to catch small fish, pick leeches off the legs of turtles, steal worms from American Robins, raid nests, and kill and eat
    adult birds.
  • Grackles have a hard keel on the inside of the upper mandible that they use for sawing open acorns. Typically they score the outside of the narrow end, then bite the acorn open.
  • You might see a Common Grackle hunched over on the ground, wings spread, letting ants crawl over its body and feathers. This is called ‘anting’, and grackles are frequent practitioners among the many bird species that do it. The ants secrete formic acid, the chemical in their stings, and this may rid the bird of parasites. In addition to ants, grackles have been seen using walnut juice, lemons and limes, marigold blossoms, chokecherries and mothballs in a similar fashion.
  • In winter, Common Grackles forage and roost in large communal flocks with several different species of blackbird. Sometimes these flocks can number in the millions of individuals.
  • Rarely, Common Grackles nest in places other than their usual treetops, including birdhouses, old woodpecker holes, barns, and in still-occupied nests of Osprey and Great Blue Heron.
  • The oldest recorded Common Grackle was 22 years 11 months old.
The Common Grackle builds nests of twigs, grass, hay, sometimes cemented with mud lined with fine grass between six and sixty feet high on branches preferably in coniferous trees, although not picky and sometimes in tree hollows and abandoned cavities, often near or over water. Sometimes they nest in numbers in the same tree for safety and sometimes even nest in a small opening in the lower parts of an Osprey's nest of sticks.

  • One smart Grackle!

    Watch this one problem solve.

    Where are Common Grackles found and how are they moving?

(Darker red showsa greater concentration of these birds.)
  • Sources:
    • Wikipedia
    • Cornell’s All About Birds
    • The Crossley Guide – Eastern Birds
    • Kaufman Focus Guide – Birds of North America
    • Smithsonian Field Guide to Birds of North America
    • Stokes Field Guide to Birds of North America
    • Wikipedia
    • YouTube

3 comments: said...

I live in Windsor, ON Canada where the common grackle is well, common. I know they are an omnivorous bird but I was astonished to see one eating a house sparrow the other day underneath our backyard birdfeeder! I'd seen blue jays before eating featherless nestlings taken from smaller
birds' nests and perhaps this hapless sparrow may have been a juvenile as it was fully-feathered, I don't know as I didn't get to see it close up 'cause when I went outside to get a better look, the grackle flew off with the carcass. I don't know if it actually killed the sparrow or the bird was already dead. Is this unusal behaviour?

Beverly said...

Absolutely! Nearly any large bird will eat a smaller bird; Jays are notorious nest robbers, as are all the grackles. My neighbor Polly watched one peacefully feeding near other birds when it suddenly attacked a small sparrow and shook it hard, thumping it on the ground to kill it. And then it ate it. I have watched grackles swallow dead mice (from my house traps) that I toss one gulp.

Anonymous said...

is there a proper way of culling these grackles? When I look up to see other species of birds flying, the ratio of grackles overwhelm the sky.

5 years ago there was a vast population of other birds with sweet songs filling my ears. Now my eyes watch these horrible black birds kill off others either by nest robbing or flying in large numbers and then ganging up and killing adult species who aren't able to reproduce because of these grackles.

Doesn't anyone see this forthcoming problem? Save the mockingbirds!