Sun, 06 Jan 2013 19:52 UTC
In Houston, they tried air cannons so loud neighbors called in the SWAT team. In New Mexico, it took a half-dozen men and thousands of explosives. In Austin, technicians go out night after night with heavy-duty lasers. All to battle an 8-ounce, highly adaptive bird that's colonizing the country -- and leaving behind inch-thick layers of droppings as it goes.
The great-tailed grackle, called by some the devil bird, is lovely to look at. Males are jet-black with a violet-blue iridescent sheen to their feathers that made them prized by Aztec kings in their original range in Central America. But while they once were seen only in the most southern tip of Texas, today they're in 23 states, as far north as Montana and as far west as Washington.
That might make them nice for bird watchers. But for residents of areas they colonize, not so much. Grackles tend to congregate in large flocks and like shopping centers and fast-food store parking lots, where there's trash for food and trees or light posts for perching. Their droppings can spread disease, and they can damage citrus crops.
They're also known for their annoying, almost mechanical call that begins at dawn and dusk. Add to that their frequent attacks on other birds, and they're simply not good neighbors.
"They're an unstoppable machine," said Alan Clark, a bird biologist at Fordham University in New York City. "They're really hard to scare, they're hard to kill and they're in such huge groups that even poison isn't particularly effective."
In October, a group arrived in San Francisco, part of their relentless march north and west. "Up to six males and at least one female have been seen in the area. They are part of an overall range expansion," said Joseph Morlan, an ornithology instructor at the City College of San Francisco.
When they arrive in flocks, they cause trouble. The Kroger supermarket on West 43rd Street in Houston has been fighting a grackle invasion for over three years. "We were inundated with thousands at a time," said manager Jeff Bailey. They buzzed customers' heads and their droppings were everywhere. The live oaks and sycamores around the perimeter of his parking lot would be "just black with birds," he said. The noise, especially in the mornings and evenings when they roost, was deafening.
Last year, workers tried using a "bird cannon" on the store roof to scare them away. Unfortunately, the loud noise it made was so much like mortar fire that when they set it off neighbors called 911 and squads of police cars arrived with sirens wailing and lights blazing.
This year, the store hired a new pest management company that sprayed a grapeseed extract on the trees. It doesn't harm them, but the birds don't like the smell and don't like their feet to touch it. "Knock wood, but so far it's working," Bailey said.
Portales, N.M., has been fighting the grackle species for about a year, said Public Works Director John DeSha. At night and in the morning, he has seen as many as 5,000 in the trees on the town's square. Human health became an issue. "They have a lot of feces involved with them. You'd clean it up one day and the next day there might an inch or 2 inches of bird feces out there," he said.
After multiple deterrents were tried, the town finally found a labor-intensive method that has worked so far. Just at dusk, a half-dozen city workers hang tin buckets containing a string of 50 Black Cat firecrackers in the trees. Each tree has a staffer assigned to it, all with two-way radios. Then "we'd light them all at the same time," DeSha said. "The sound and light and vibration, the shock waves, would drive the birds up in the air." Several nights of this trains the birds to find somewhere else to roost. To avoid calls to police, his office did a "huge media blitz to let everybody know what we were doing," he said.
Rodney Beaman of Texas Bird Services has contracts with multiple cities and businesses to get rid of grackles.
His Arlingtoncompany has found high-powered lasers most effective. "You move it back and forth" on the trees and "their senses cannot adapt," Beaman said. He sends out teams of three to seven technicians just before dusk who spend several hours shining lights at the trees where the birds are roosting. After three to 10 nights, the flock leaves. But in the spring and fall, new flocks arrive almost daily, so he has to have staffers out every night for about four months.
For really stubborn flocks, he'll hire a falconer who will fly hawks into the tree. "They take out a few grackles, and then the rest leave," Beaman said. "But it's only good for a few trees, you can't do a whole neighborhood."
Grackles get their name from graculus, the Latin word for jackdaw, a European black bird. The great-tailed grackle is distinguished from its close cousin the common grackle by its larger body, and the male has a long, keel-shaped tail. The two species tend not to interfere with each other, said Dan Cristol, director of the College of William & Mary's Institute for Integrative Bird Behavior Studies in Williamsburg, Va. The great-tailed grackles are originally a Central American species, and now they're on the move. "In the 1800s, they barely touched Texas," Clark said. Now they "increase the area they occupy by about 4% each year."
Great-tailed grackles have managed this because they're desert-dwelling generalists that adapt easily to new situations. They're fond of irrigated farmland, which has increased exponentially in the past 50 years. "They need water, trees and grain, and that's the new West," Clark said.
Another thing that's propelled their expansion is the growth of cattle feedlots across the West and Midwest, where grackles like to congregate in the winter to gorge on grain, said Mike Bodenchuk, director of the Department of Agriculture's Wildlife Services office in San Antonio. That is a major problem for cattle operations because the birds not only contaminate the feed with their droppings but can transfer diseases from one feedlot to another.
Grackles can also be a major problem for farmers. In citrus orchards, they poke holes in fruit, Bodenchuk said. In fields, large flocks can cause serious damage.
Many people in areas where they're a nuisance believe that because the birds are covered under the Migratory Bird Treaty Act of 1918 it's illegal to kill, harm or harass them. However, a special standing order has been added regarding great-tailed grackles that allows them to be "harassed and removed without permit," said the USDA's Bodenchuk. The order applies if the birds are harming crops, damaging plants, affecting human health and safety or even if they're simply a nuisance.
"If you've got a tree outside your bedroom window and they're keeping you awake, you can go out and kill them if it's OK in your area," Bodenchuk said.
The problem is that killing them doesn't do much, he said. "If you kill 10, 10 more will show up."