A Complete Guide to the Common Grackle's Behaviors
Introduction
The Common Grackle is related to the Red-winged Blackbird. But unlike the Red-wings, Grackles nest in colonies and only protect the area of the nest.
Their mating rituals, nesting habits, and feeding behaviors 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: Size and Field Marks
Measuring about 12 inches in length, the Common Grackle (Quiscalus quiscula) is a medium-sized blackbird with a distinctive appearance.
Common Grackle
It has a long, tapered tail and a strong, slightly curved bill.
Adult males have iridescent black feathers that can appear purple, green, or blue in certain lighting conditions.
Their eyes are a striking pale yellow, which contrasts with their dark plumage.
Females are slightly smaller and less glossy than males, with a more brownish hue to their feathers.
Both sexes have long legs and a somewhat flat head shape, which gives them a unique silhouette.
Mating and Breeding Habits
The breeding season for the Common Grackle begins around mid-March and through the month of April. By May most pairs are formed.
Mating rituals are simple. Following one female, several male Common Grackles will land around the female and perform several displays trying to attract her.
In-flight, you can identify the males as they 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.
Nesting Habits: Building and Materials
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.
Egg Laying, Incubations, Fledging
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 - Diet
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 Them 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.
These roost can number in the tens of millions and be a nuisance if located near urban areas. Large flocks can damage grain crops.
Lifespan
Studies show that Common Grackles live longer than most of our backyard birds. Lifespans of 6 - 7 years is common. Maximum lifespan recorded is 22 years.
While some have lifespans beyond 7 years the percentage drops significally after 8 years. UNM edu citation
Do They Mate for Life?
While Common Grackles are considered mostly seasonally monogamous, they do not mate for life.
Some males may even breed with other females while the first female is incubating eggs.
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
Predators of the Common Grackle include squirrels and snakes which eat the eggs and young birds. Cats, raccoons, along with some Hawks and Owls also prey on them.
The Common Grackle is protected by the Migratory Bird Treaty Act.
