Until recently, when people thought about biodiversity along midtown's Arroyo Chico, they might have pictured neighborhood kids on mountain bikes, or bedraggled souls in homeless camps.
They might want to think again. Today, from Kino Boulevard to Campbell Avenue, biologists are busily cataloguing the flora and fauna of this overgrown drainage. And their work is occurring at breakneck speed, as construction nears for a huge flood retention project that will completely transform the lush area south of Broadway Boulevard.
What's emerging from their field work is the picture of a surprisingly diverse habitat, right in the heart of the city. In particular, Arroyo Chico is home to a little creature called the regal horned lizard. And on most days this summer, you could find UA herpetologist Phil Rosen counting those distinctively crowned lizards, beneath a canopy of renegade oleanders and eucalyptus that have immigrated from surrounding neighborhoods.
Rosen says there's a very short window of time to tally lizard numbers, figure out how many need to be relocated and devise a strategy for reintroducing them once the 29-acre Arroyo Chico basin is complete.
The work is particularly important now, because biologists worry that the lizard's numbers may be plummeting. "There's a strong population in Arroyo Chico," says Rosen. "But this September, they'll be bulldozing everything and creating basins. Then they'll try to re-vegetate and create some viable ecology in there. But in the meantime, they would almost certainly completely extirpate the horned lizard population there."
The plan, he says, is to remove the lizards before the bulldozing, "and find out if there are places in Tucson where they can be 'stashed.' And then finding out ultimately whether flood-control basins are providing habitat for the lizards."
Still, the fact that Pima County is taking the time and spending the money—around $60,000 for environmental consultants from RECON Environmental Inc., which hired Rosen—signals a growing recognition that conservation doesn't begin at the city limits. We're not alone: Across the country, cities and counties are including wildlife needs in their planning processes, and enhancing urban environments that have become increasingly critical to species survival.
Indeed, it's becoming increasingly clear that cities are veritable harbors of biodiversity; in New York alone, scientists have found more than 3,000 species of plants, including 1,000 that are considered exotic or nonnative.
But while a greater recognition of urban ecology is encouraging, it's also a trend fraught with potential missteps, says Kieran Lindsey, co-author of the seminal 2005 book Urban Wildlife Management, and director of the Natural Resources Distance Learning Consortium at the Virginia Polytechnic Institute.
"There has been a move toward recognizing that there's no place that isn't habitat," says Lindsey. "And that is not the way we always thought about it—even though we've always been surrounded by wildlife. There's a growing appreciation that, at least for species that are adaptable, if there is a place to live and a way to live there, there will be non-humans who will try to take advantage of that."
But while this growing recognition does color the design of urban projects such as the Arroyo Chico basins, she says, it doesn't let us off the hook for ravaging habitat in the first place. "People want it both ways. They want to do what they want with the land, whether it's a building or a road or whatever. I have a belief that most people want to do the right thing for wildlife as well.
"But when wildlife moves back into an area that's been developed, it may not be the same species that was there before the development. It may not be the same biological community that was there previously."
Therein lies the challenge of Arroyo Chico. Much of what's living there now will be removed, says RECON project manager Carianne Funicelli Campbell. That includes nonnative plants ranging from Russian thistle to red brome. They'll be replaced by native vegetation, such as mesquite and palo verde, with a goal of re-creating some semblance of habitat improvement.
Topping the list is the regal horned lizard, which relies on a certain habitat—namely one containing lots of tasty ants—for its survival. "And what's special about this project," she says, "is that there's an intact population of the horned lizards right in the urban core."
That did not go unnoticed by planners, says Thomas Helfrich, water resources division manager for the Pima County Regional Flood Control District. Helfrich is a veteran of such projects, having been deeply involved in the 60-acre Rillito Swan Wetland, a $3.5 million project aimed at re-creating willow and cottonwood-lined habitat along a portion of the Rillito River. Completed in 2008, the project diverted three neighborhood washes onto an abandoned construction landfill. It involved a measure of flood control, as well as habitat preservation and restoration after Rosen discovered large populations of toads in the area.
Workers carefully avoided disturbing active breeding sites for several toad species, says Helfrich. "After construction, we then began monitoring the site. And we've observed over the last couple of years that toad populations are pretty healthy in there even after our construction. There were tadpoles in many of the ponds that we either preserved or created as part of the micro-landscaping. The habitat is re-establishing itself and a lot of wildlife exists in that area."
Helfrich says his department is pushing for that level of ecological sensitivity across the board. The goal "is to have projects that are not only successful from a public safety perspective, but also work with the environment and the wildlife. Flood Control, I feel, is one of the leaders in doing this. From our upper management down, it's been supported."
That carries over to Arroyo Chico. "It is a public safety project," he says. "However, we looked at the plant and animal species that lived in that area, with a couple of species of interest."
Once again, primary among them was the regal horned lizard population first identified by Rosen. "Can we relocate them?" asks Helfrich. "Can we mitigate destruction of their habitat or their food source? How will they re-adapt to that area once our project is complete? We really don't know. This is something the Flood Control District has been trying to do for the last four or five years, and we are learning from it."
But even with that knowledge, there's always a choice about what does or doesn't get saved, says Lindsey. "Chances are there's not going to be one solution for every species that's living in a particular area. So you come back to a value judgment, where you're trying to decide, 'What is it we're most concerned about?
"Is it that we have a species in jeopardy or is it that we're trying to improve public safety? What is it we're accomplishing and which species are we trying to have an impact on?'"