Common Grackles Mating, Nesting, Feeding Habits

In Spring, hundreds of Grackles arrive in my neighborhood causing havoc. Filling the trees like black leaves and making an enormous amount of noise.

Usually, they gather in the morning, flying from tree to tree and squawking until a large number have gathered.

Then, out of nowhere, a group flies off. Seconds later, another group follows.

This continues until all are gone. And just like that, everything gets quiet again.

Common Grackle Perched on Power Line

Common Grackle

The Common Grackle is related to the Red-winged Blackbird. But unlike the Red-winged Blackbird, Grackles nest in colonies and only protect the area of the nest.

Their mating, nesting, and feeding habits are better observed as a group and not as a single pair.

Since they are colonial, to distinguish a pair of birds from a flock can be difficult.

Common Grackle Call

Description

Measuring about 12 inches in length. Males are black with iridescence on the head, back, and belly.

The iridescence on the body is purplish on birds from Southeast to S. New England, and bronze on birds elsewhere.

Females are similar to males but with a shorter flat tail and less iridescence.

Mating Habits

Beginning around mid-March and through the month of April, the Grackles mating season gets underway.

Following one female, several male Common Grackles will land around the female and perform several displays to attract the female.

In-flight, you can identify the males. They will fly with the V-tail flight display during mating season.

As the mating and courtship season continues, the number of males following a female decreases until there is just one male to one female.

Common Grackle Nesting Habits

Both males and females will bring nesting material to the nest site. This process takes from 1 to 4 weeks, but it's not the actual act of nest building.

The actual nest building is done after this period, and by the female only. She completes the nest in about 5-days.

The nest is made of grass, twigs, reeds, and mud. The inside is lined with finer materials.

You can find the nest in a shrub or tree 3 to 30 feet above the ground or water.

The female will lay 4 to 7 eggs that are pale greenish brown with dark marks.

Incubation of the eggs will last about 13 to 14 days, with the young leaving the nest in about 12 to 16 days after hatching.

Common Grackle Nesting Stats
Eggs 4 - 7
Incubation 13 - 14 days
Nestling Phase 12 - 16 days
Broods 1

During this time, the male Grackle may guard the nest while the female feeds. Also, the male may pair with a second female during this time.

In such cases, he rarely returns, leaving the female to raise the brood by herself. Only 1 brood is raised each season per nest site. Second broods are rare.

Feeding Habits - What Common Grackles Eat

Grackles will frequent backyard feeders during spring and summer in large numbers. They feed on a variety of seeds. Two of their favorites are sunflower seed and cracked corn.

Sometimes, they can be a problem at feeders. They will empty the feeders so quickly and keep smaller birds away.

If they've become a problem for you, try selecting a type of feeder that restricts larger birds from getting to the seed.

Grackles will steal the young from other birds just as the other young hatch. I've seen newly hatched Cardinals get attacked by these aggressive birds.

They tend to attack very early in the morning. Usually, several will arrive at a nest site and cause the adult Cardinals to try to protect the nestlings.

While the Cardinals are chasing one Grackle, another Grackle bird steals the young.

Keeping Grackles Out of Bird Feeders

While you can alway use bird seed that they don't like, such as safflower and nyjer seed. That's not always practical.

Limiting the type of seed you offer works, but it also limits the birds that come to your feeders.

My favorite way of keeping them out of the feeders is by using Caged Bird Feeders. These allow the smaller birds in while keeping the large birds out.

In Fall, they'll form large roosts that by winter, will include Red-winged Blackbirds, and Cowbirds that can number in the tens of millions and be a nuisance if located near urban areas.

Large flocks can damage grain crops.

Other Behavior

The Common Grackle nest communally and has a habit of using swimming pools to drop the waste of their young.

Some believe this is because they have a sense of rivers and streams washing the waste downstream, away from nest sites.

This practice works to their advantage as it makes it difficult for predators to find the nest due to no scent.

Unfortunately for the pool owner, hundreds of droppings from several nests will make daily cleanup a necessity.

There isn't anything one can do except wait for the young to leave the nest. This will end the need to carry waste away from the nest.

Predators of Common Grackles

Predators include squirrels and snakes eating eggs and young. Cats, raccoons, along with some Hawks and Owls prey on them.

The Common Grackle is protected by the Migratory Bird Treaty Act.


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