Even though grackles might seem like they are taking over the city, University of Texas biology professor and longtime birder Peter English doesn’t consider grackles invasive or even dominant because they are not taking resources away from another bird species.
“Grackles aren’t dominant; they are just successful,” he says. “A dominant species is one that is expanding its niche to exclude others. White wing doves expanded to the detriment of mourning doves and Inca doves and the things that used to be common here. Blue jays are pushing scrub jays out of Westlake, and ravens and crows have moved in because of the drought. These birds weren’t here when I was a kid,” he says.
Residents of Austin have a complex relationship with great-tail grackles, which are known to flock grocery stores, restaurants and parking lots in large numbers.
Grackles take advantage of the ecological “dead zones” in the parking lots of big stores and shopping centers. “The grackles didn’t make the parking lots with trees that are exactly the right size for them and that are spaced widely enough to allow them to have independence and yet be part of a larger group,” he says. “We made that.”Meet the Grackles: The secret history of Kevin Russell’s early-’90s band
Grackles have what’s called a high carrying capacity, which is the number of individuals that can live in an area without causing the resources to be depleted. Because humans create so much food waste and so many power lines for perching, grackles have a naturally high carrying capacity.
“Grackles aren’t moving anybody else out,” English says. “Starlings, on the other hand, compete for hole nesting, and cowbirds lay eggs in other birds’ nests. Those would be considered invasive.”
Other birds in the area might eventually figure out that there’s a free food source and try to compete for it, but that’s the only threat to grackles, English says.
Not even the starlings are giving grackles a run for their money.
“It’s like saying, ‘Here’s unlimited food forever and no predators,’” he says. “If you are going to create a habitat that is tailor-made for a species, give it unlimited food and then complain about it? That’s your problem.”?MORE: Experience all things grackles with Grackle Week 2018?