Two weeks ago in Florida, as we watched boat-tailed grackles fly by one after the other, my wife remarked, “I’ve heard they are becoming less common.” When I looked into it, I found that she had heard about the common grackle (Quiscalus quiscala). The species has become a little too common and population control measures against it seem to have been effective. Its eastern population has declined by 50% since 1966.
When crows gather in a group, they are called a “murder.” When Q. quiscala gathers, it is “a plague of grackles.” Along with the red-winged blackbird, grackles make the most significant inroads on agricultural crops. And for that they are not only despised, but killed. In spite of being classified as “Near Threatened” because of their steep decline, you are not in danger of never seeing a grackle again. The population has decreased from a high of 190 million to the current 71 million. In addition, the species is spreading westward and increasing in that part of its range.
This grackle breeds from the Northwest Territories in Canada southward through Colorado to central Texas. In the east it ranges from Newfoundland down to Florida. We live at the northern edge of the vast area south of which the grackle is a permanent resident. They return to my neck of the woods in very late March or early April. They are not particularly common in my immediate vicinity because our area is so heavily forested. Grackles prefer open country, and it was the spread of agriculture after European settlement that caused the species to become so common and to continue to extend its range to the present day.
The grackle eats anything: mostly berries, seeds, and grain (averaging 70-75% year round), but also invertebrates, small vertebrates, and eggs. They also have an unfortunate habit of pulling seedlings out of the ground and not eating them. They forage mostly on the ground and, in the non-breeding season, often alongside other blackbirds and starlings. Their bill is an adaptable and formidable tool; it is serrated and can be used to score acorns until they are fragile enough to be cracked open by biting down on them.
Although you will usually see them walking on the ground moving things around with their bills—not their feet—to see whether it is edible or not, they have other means of finding food. Along shorelines they will wade in to snap invertebrates out of the water column or hover over the surface and snatch minnows from just below the surface. They follow plows to look for insect larvae that are turned up, but if a mouse is flushed, they are not above pecking it to death and eating it. Finally, they have been known to rob the nests of other species of both their eggs and nestlings. Grackles are tough customers.
In addition to eating grains (including rice), grackles are also excessively fond of sunflowers, blueberries, peanuts and sweet cherries. A 1981 study found that grackles were responsible for >$81 million in damages to agriculture. Not only do they eat grain and destroy seedlings, but their depredations require farmers to take expensive measures to prevent further losses. Methiocarb, a chemical banned by the European Union because of its toxicity to many kinds of organisms, is in the United States sprayed on corn seedlings to prevent grackle and blackbird damage.
Deterring and killing grackles has become an industry. Type “grackle population control” into your browser. The first site that came up for me was a company which offered products to scare them away with audio, frighten them with visuals, shock them, exclude them with netting, or discourage them with “taste repellents” (of which methiocarb is an extreme example).
In 2020 the U.S. Department of Agriculture published a “technical paper” in their Wildlife Damage Management series called simply “Grackles.” After teaching you how to identify the bird and describing the damage they cause, it moves on to “Management Methods.” These escalate from “habitat modification” through all of the above described methods to shooting, trapping, and preferred methods of euthanasia.
In case you are wondering how it is legal to do all this to a “songbird,” the USDA explains, “All grackles are federally protected by the Migratory Bird Treaty Act, but actions to control damage, including lethal take, is allowed under a “Standing Depredation Order” (50 CFR 21.43) which allows take of grackles ‘…when found committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock or wildlife, or when concentrated in such numbers and manner as to constitute a health hazard or other nuisance.’ The federal standing depredation order overrides state regulations or the need for a state permit.”
The part about “a health hazard” refers to the transmission of disease. Like most blackbirds, grackles gather in large numbers to roost for the night. If they use a location for more than a few years, it becomes infected with Histoplasma capsulatum, a fungus that causes histoplasmosis, a sometimes fatal respiratory disease. In this context the birds are killed with a surfactant, PA-14-a, which causes their feathers to become wettable and the birds die of exposure.
In one dramatic incident in Austin, Texas in 2007 (reported in Time magazine), grackles began falling out of the sky, dead, onto the streets of the city. Autopsies revealed them to be riddled with parasites throughout every organ and bone in their bodies. Thus weakened, they were dying in mid-air due to an unusual cold snap. Parasites are spread when animal populations are extremely dense. This is seen not only among birds, but with chronic wasting disease in white-tailed deer.
The lesson of the grackle is that when humans alter the landscape with monoculture crop growing there is going to be an ecological response. Grackles became over abundant because there was just too much food available to them. The long-term solution is not to keep killing them.
Bill Chaisson has been a birdwatcher for over 50 years. He lives and works in Wilmot.
The View from Shin Hollow 