Meanwhile, the DTC will hire people to go on permanent poop patrol because the city's sidewalk maintenance "is not [big] enough to keep up with the birds," she says.

City crews spray the sidewalks less than once a week. But the poop needs to be washed off sidewalks, benches, and other surfaces every day. The $75,000 a year "is a pretty big single expenditure" for the DTC, but a necessary one, Goronkin says.

"Frankly, it's a mess," Goronkin says of the birds' ability to coat the downtown area. "I've had them poop on my head."

Goronkin says that the developers of north Scottsdale's Kierland Commons planted numerous ficus trees along the streets of the outdoor mall, wanting to replicate the shady sidewalks of Mill Avenue.

"I'm hoping," Goronkin says, "the grackles and starlings go there."

Trouble is, there are grackles aplenty to infest both places.