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.