WILDLIFE :: GRACKLE

Common 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 a single pair. Since they tend to be colonial in nature, distinguishing a pair from a flock can be difficult.

Description: The Grackle is about 12 inches in length. The Grackle appears all black at a distance, but is actually highly iridescent, with colors varying from blue to purple to green to bronze, depending on the light. Grackles have bright yellow eyes. Female grackles are duller and somewhat smaller than male grackles.

Nesting: Both male and female Grackles will bring nesting material to the nest site. This behavioral habit is done over a period of time lasting from 1 to 4 weeks. The actual nest building is done after this period, and by the female only, which she completes 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 located in a shrub or tree 3 to 30 feet above the ground or water.

Mating Habits: Following one female, several male Grackles will land around the female and perform several different displays in an effort to attract the female. In flight you can identify the males as they will fly with the V-tail flight display during mating season. 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. 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, and the female then raises the brood by herself.

Diet: The grackle is an opportunistic feeder, varying an insect and grain diet with both the eggs and the young of small birds. Their diet consists of a wide variety of animal and vegetable food, including insects and invertebrates but also 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. 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. These 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.

Problems: Grackles can cause a variety of bird control problems. When Grackles are in their flocking phase, thousands of these pest birds can literally overwhelm trees or buildings in an area. Large scale buildup of their sprayed feces (a whitewash look) can lead to structural damage as the uric acid in the pest bird droppings can corrode stone, metal and masonry and damage paint finishes on cars and other painted surfaces. These birds can also present a very serious health risk. Common grackles are one of the most significant agricultural pests today, causing millions of dollars in damage to sprouting corn. The roosting sites of common grackles and other blackbirds may harbor the fungus, which causes histoplasmosis, a human respiratory disease that can be fatal.

Solutions: Grackles are protected by the Migratory Bird Treaty Act, a federal mandate. However, if the birds become a public nuisance and a public health risk, actions can be taken to control these pests if they get to the point of damaging property.

The grackle epidemic peaks this time of year, as common grackles migrate from the northern regions of the U.S. and Canada to the state's warmer climate.  They join an already huge population of native great-tailed grackles, a large, noisy bird with a 25-inch wingspan, iridescent purplish-black plumage and a V-shaped rudder of a tail.  After feeding all day in rural pastures and fields, the grackles gather by the thousands in colonies and head for favorite roosting spots in cities.  Grackles adapt well to urban life where it is warmer among buildings and there are few predators. 

Grackles have become one of those readily adaptable species.  They are aggressive birds that consistently outwit the tools utilized to scare them away.  The City of San Antonio first attempted displacing roosting grackles ten years ago, by dropping firecrackers into galvanized metal trash cans placed under the trees.  The birds just moved to the next tree.  Next the city began using noise-making "cracker shells" fired from shotguns, with shotgun-wielding crews deployed to different parts of the city to chase grackles from tree to tree.  The grackles simply moved to another location only to continue being a nuisance.

The City of Fort Worth, in attempts to rid downtown of the birds, has attempted numerous techniques over the years but to no avail. They are currently attempting to use lasers, lights aimed at the flocks, cracker shells, and a grape based fog in an effort to permanently displace the birds.

The City of Arlington's Animal Services Division continually monitors new techniques employed to deter grackles, but has not identified an effective means of permanently displacing the birds. 

There are numerous non-lethal products and techniques available to combat nuisance grackles from nesting on private property. No endorsement of specific brands or any product line, provided below, by the City of Arlington is implied or intended by inclusion here.

Grackles can be moved with audio visual (noisemaker) bird scare products if the bird scare products are implemented quickly when the birds move into an area.

Strobe Lights—Some acoustical alarms (above) incorporate strobes. Inexpensive strobe lights are sold by many home gadget retailers. The following vendors sell larger, more expensive units designed to evict roosting birds:

A new technique for grackle problems that has found some success is fogging with methyl anthranilate, a grape extract that reacts with the birds olfactory sense like pepper spray.