It's bird poop. Lots of it.
The culprits: thousands of grackles, starlings, and other birds that have made Mill Avenue their home in the past few years, despite numerous efforts to deter them.
The unluckiest Mill Avenue visitors don't just see the problem; they feel it. A stroll down the shade-tree-lined street risks multiple wet plops of warm, white avian feces. In your hair. On your clothes. Meals eaten on the outdoor patios of some restaurants may include an un-ordered side dish.
They're not just gross — the blackbirds are noisy as hell, too. Especially the grackles, which sing particularly loud and obnoxious songs.
When the twilight sky glows orange during peak bird season — from autumn until the first month of summer — countless thousands of birds descend on Mill. They whistle and shriek as though they've been nipping fermented fruit. It's a din by evening.
An online bird guide by Cornell University describes the grackles' chorus as sounding like a "rusty gate" and their call "a sharp, harsh chack." The birds can be aggressive and have been known to peck humans. They have taken over cities other than Tempe and are even the subject of a 2005 movie, Day of the Grackle, about a man vexed by one of the bothersome creatures.
The bird situation is revolting to the Valley's premier college town, which has built a reputation as perhaps the only place in metro Phoenix that feels urbanized.
Feeding off the energy of nearby Arizona State University, downtown Tempe's Mill Avenue evolved from a strip of biker bars in the 1970s to a quaint collection of storefronts and eateries in the 1980s to a slick (some would say soulless), slightly upscale collection of corporate chain storefronts and eateries in the 1990s and 2000s. Mill has a patina of city life, where bums and screaming Bible thumpers don't get tossed like they would from a shopping mall, and where heavily tattooed freaky people mingle with freshly scrubbed yuppies pushing strollers.
Walking on Mill past all these stores, restaurants, bums, and freaks — while nicely shaded by tall ficus trees — is part of the experience that draws people to the place.
But something's literally pooping on the parade.
In desperation, the city of Tempe tried various inexpensive methods over the past three years to scare away, or otherwise roust, the birds from their roost. Nothing's worked.
Now Tempe's given up and tossed the problem to the city's merchant-funded Downtown Tempe Community association. But the DTC hasn't figured out an answer, either.
So it's begun treating the symptoms instead of the problem. In its 2008-09 fiscal-year-operations budget of about $550,000, the organization's put $75,000 toward a new program of intensive, daily sidewalk and brick power-washing.
You read it right: The DTC's now aimed about one-seventh of its annual budget at cleaning up bird droppings.
No doubt it's going to be money well spent, because visitors and tourists to downtown Tempe might stop coming if Mill Avenue continues to get crapped on.
Grackles, like rats and coyotes, enjoy human civilization for its excesses. The small, aggressive blackbirds thrived in the New World for millennia before European settlers arrived, and (unlike many an unfortunate native species) they're still thriving.
Arizona is home to a slightly larger version called the great-tailed grackle, which (like many of the human beings here) originally hailed from Mexico. Their expansion into what is now the southwestern and midwestern United States coincides with the country's development. They don't migrate, though they do flock in lesser numbers during summer.
Like coyotes, great-tailed grackles look scrappy and tough. They have beady, yellow eyes. The black feathers on their heads and bodies seem iridescent.
The other type of bird infesting downtown Tempe, the European starling, has been equally successful at exploiting the world built by mankind. According the 2007 book The World Without Us, they were first released in North America in the 19th century by a New York City resident who (no shit!) labored to bring in every type of bird mentioned in William Shakespeare's plays.
Pigeons, doves, and finches also are attracted to Mill Avenue. Birds must love all the crumbs dropped by partiers who snack between bars. The twice-annual arts and crafts festivals and many other special events (before cleanup, anyway) must look like pure heaven to the avian scavengers.
But it's not the food that draws the flocks of grackles and starlings. It's the trees.
The city planted 120 ficus trees along Mill in 1985 to beautify the street and to provide shade. The trees grew wonderfully in the following two decades. Their trunks are fat and healthy, their tops bushy and packed densely with bright green leaves.
The grackles and starlings have been enjoying the ficus trees for years. But about three years ago, after the canopies were fully matured, the birds apparently told all their friends that Mill's the place to be, because that's about when Tempe's arborist, Steve Amelotte, noticed the area had been hugely invaded.
On-street parking and more outdoor dining patios added since 2002 exacerbated the problem. To continue the air-assault theme, it could be said that all those extra birds flocking to Mill found a target-rich environment.
The birds use the trees as sleeping quarters at night and for rest stops during the day. All the while, their digestive systems drizzle poop on the hapless humans and infrastructure below.
But they aren't fouling their nests, which are dispersed through the Valley, says ASU grackle expert, ecologist, and assistant professor Kevin McGraw. Sleeping at nest sites draws too much attention from predators. Another facet of their survival wisdom, McGraw says, is roosting together in large numbers near electric lights: They're more likely to see approaching predators and less likely to be eaten by larger birds.
Grackles are aggressive.
"If you put out seeds," McGraw says, "grackles will sift through the seeds to find what they want and chase other birds away."
Grackles aren't easily put out, or snookered.
With a budget of only a few hundred dollars, Amelotte and his crews tried thinning the ficus branches, but they couldn't thin them enough. If branches are thick enough for shade, there's enough wood for the small feet of the resting birds. Amelotte tried playing amplified recordings of distressed birds, but the real birds weren't fooled. He tried coating the branches with slippery foam, but it dried quickly and the birds paid it no attention.
"A grackle's an amazing bird!" Amelotte says, begrudgingly. "That bird does what it wants to do exactly when it wants to."
Amelotte says he consulted with a Chandler man who runs a business called The Pigeon Guy. Oddly, Tempe officials and the city's business association, the DTC, never bothered to call ASU in the past three years to find out whether anyone could help.
McGraw, who works in a lab in the Life Sciences building on ASU's main campus, is an expert on both grackles and bird removal.
But he's unsure what should be done about the grackles.
Oh, he knows how to get rid of the birds. But the solution's drastic and controversial — he wants no part of it.
Basically, he says, you'd have to keep all humans off Mill Avenue for a couple of days, during which time you'd send teams carrying net cannons to catch thousands of birds. The grackles would then be released beyond their typical homing range so they wouldn't find their way back. Even then, McGraw says, it's possible the grackle population on Mill would build up again over time, requiring another relocation a few years later.
Not only that, but the non-native starlings couldn't simply be reintroduced elsewhere, per federal regulations. They'd have to be killed.
"That's not something I'd feel comfortable doing," he says.
It's also not something the Valley's many animal-rights advocates would stand for. A few other bird-control options have yet to be attempted, and aren't likely to be effective. One mentioned by McGraw is spinning, ultraviolet reflectors that look like cheap wind chimes. Possibly, the reflectors would stress out the birds enough to make them leave.
Lasers (strong enough to bother, but not blind, the birds) could be aimed into the trees. In the Dallas-Fort Worth area, which has seen an invasion of grackles in parks and downtown areas, a DTC-like group hired a company that uses a hawk to hunt and kill grackles. In theory, the presence of the hawk (after a couple of days) scares the grackles enough to make them find other homes. So far, the brave blackbirds haven't backed down, says George Kruzick, a Fort Worth parks supervisor.
Propane cannons have proved an effective, albeit temporary, deterrent. Cannons, mounted on trucks that drive by infested trees, automatically blast sound and heat every minute or two at the birds. A few days of the blasts force the grackles to skedaddle for a week or more before determining it's safe to return. But there's a downside to this method: "It does disturb people," Kruzick says. "No doubt about it."
Because of the noise, officials have decided not to use cannons in downtown areas or places where tourists gather. Noise-wise, the solution is worse than the problem.
That's why cannons probably won't be used on Mill, says Pam Goronkin, the DTC's executive director. But she's definitely on the lookout for some kind of fix.
At the end of the summer, before the birds come back in force by October, the DTC will pay landscapers to trim the ficus branches even more. That will reduce some of the shade, but it should lessen the number of birds and, thus, slow the build-up of feces.
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.