Native Southwest plants and animals are rapidly disappearing from our area of the state. Jennifer Patton, a local landscape architect, and her husband and business partner Ben Wilder investigate the reasons why, and what can be done to stop the extinction.

The fading daylight and steady drizzle make it hard to see the hole in the trunk of the mesquite tree that we have been watching for the last half hour in hope of hearing or seeing the owl we believe will come out for the evening. My husband Ben and I are in northwest Tucson, having spent the day on this site tagging saguaro and barrel cacti, mesquite, palo verde, and ironwood trees as part of a native plant inventory, required prior to the site being graded for a proposed residential development. During the day we startled a large covey of Gambel’s quail, observed a red-tailed hawk constructing her nest in a multi-armed saguaro, flushed a pair of great horned owls from an immense and ancient foothills palo verde tree, and surprised a small flock of reclusive black-throated sparrows. And toward the end of the day, as we were tying a red flag around the branch of a mesquite slated for removal, we noticed movement inside a cavity of the tree. Something feathered and gray, watching us.

We have never seen a cactus ferruginous pygmy owl in the wild (few have, as this species is rapidly diminishing in Southern Arizona due to habitat loss). But we know we are in prime pygmy owl habitat — the parcel we are inventorying, 40 acres or so, is undisturbed and thick with ironwood and saguaro — key habitat for the bird. It could be a pygmy owl. With the aid of a game camera and several visits back to the site, the mystery bird revealed itself as a ladder-backed woodpecker. A year later, while doing research for this article, we realize that the site we were on is right in the middle of the 1990s battleground of the pygmy owl versus development. At that time, roughly 20 owls made their home in Northwest Tucson. Today — none. Another victory for development. Another loss for diversity.

What is Species Loss?

Extinction is the disappearance of a species from the planet. The ivory billed woodpecker, the western black rhino and the passenger pigeon are well-known examples of animal species that were driven to extinction. In Southern Arizona, the jaguar and ocelot, both endangered species, have headlined recent news stories, as shrinking habitat and loss of connectivity threaten to extirpate these species from Arizona, and heighten the eventual likelihood of their extinction. These majestic cats capture our attention more than numerous other species in our region facing similar fates, including six species of chub fish (Sonoran, Gila, bonytail, Yaqui, humpback, Virgin River), desert pupfish, the Sonora tiger salamander, the Chiricahua leopard frog, and the southwestern willow flycatcher. Gaining even less coverage than amphibians are hundreds of insect and plant species disappearing before many of us have ever noticed them.

Extirpation is extinction on a local scale. A species once common in an area is no longer found there, although populations still exist in other areas. The pygmy owl is an example of local extinction. Once common in Southern Arizona, and recently (1990s) in Northwest Tucson, the owl is now found only in Mexico. When the desert is bladed for development, the animals living there must find somewhere else to go, and as the human footprint increases, there is more frequently becoming no “other place.” In addition to the loss of local population, the remaining species as a whole suffers, as there is less genetic diversity and less resilience to further loss in numbers. Extinction follows on the heels of extirpation.

Cactus wrens, phainopepla, blackthroated sparrow, black-tailed gnatcatcher, flicker — once common birds in Tucson — are seeing declines from 30 to 80 percent since the 1960s. Even the verdin, a small energetic bird that is a mainstay of urban areas, is declining. The National Audubon Society attributes this to the loss of habitat and insufficient native vegetation, as well as the corresponding drop in insects that the birds depend on for food.

Sweetwater Preserve

Sweetwater Preserve, a picturesque 880-acre Pima County Natural Preserve and Trails Park.

The Main Culprits

Species loss is typically due to a confluence of factors. Shrinking and splintered habitat, water depletion, invasive species, pollution, overhunting – each is like an axe blow to the trunk of the biome. Enough blows, and eventually the tree is felled.

Randy Serraglio

Randy Serraglio, Southwest Conservation Advocate with the Center for Biological Diversity

”For many species there is more than one threat,” observes Randy Serraglio, Southwest Conservation Advocate with the Center for Biological Diversity. “It’s when you pile on one threat and another and another, and a species habitat gets fragmented into increasingly smaller pieces. Then this little population winks out, and that little population winks out, and all you’ve got left is one small group and it’s extremely vulnerable to single localized events. The resilience is gone and the genetic diversity suffers. They’re less able to deal with stresses. It’s a scientific domino effect once things start getting carved up like that. It’s a slippery slope to extinction.”

The current world population is 7.8 billion people, increasing by roughly 83 million people each year (227,000 people per day). Every person born demands a chunk of the planet to supply it with food, water, space, and an ever-improving standard of living. The demands tax the planet’s resources and stress the other species with which we share the planet.

Human expansion leading to extinction is not a new problem. With each technological revolution the human population expands. Technology may reduce our per capita ecofootprint, but it also enables us to press ever more of the planet into our service. At some point, unless we have sci-fi type technology breakthroughs, we will have to command the entire planet to service our collective hunger and wants. Imagine a planet with us, our pets, our domestic livestock, our food crops, and not much else.

At 7.28 million people today, Arizona is the 14th largest state by population and the 7th fastest growing state by either percent or number. It is estimated that new construction devours 10 square miles of desert every year.

Along with land, humans gulp up water. The year-round flow of the Santa Cruz River, once flanked by cottonwoods and willow, dried up by the late 1800s. As groundwater pumping increases to keep up with human demand, the water table drops — falling several hundred feet in the last 50 years. Humans deepen wells and pump in water in response. Plants and animals cannot. Instead, they take up residence in more favorable habitat or disappear.

The desert bighorn sheep, with herds once ranging throughout the Southwest, is emblematic of the struggle that species face with increasing human population. Bighorns historically roamed between mountain ranges, trekking through the Santa Catalina, Tortolita, Rincon, and Tucson Mountains. They move to find mates, water, food and to avoid predation. Genetic mixing between smaller populations makes for a healthy gene pool. But as human population increases, areas of suitable habitat become smaller and more fragmented. Roadways, walls, population centers, the CAP canal, even solar fields have created barriers leading to isolated populations.

In areas that bighorn remain (often through re-introduction), fire suppression degrades habitat. Underbrush thrives, hindering movement and blocking sightlines to predators. On top of this, humans hike, bike, and bring their dogs into these remaining “natural” areas. Without ample room to meet their basic needs, and no way to move to other areas, these small, in-bred populations are easily wiped out with the onset of once survivable drought or disease.

People travel to Tucson and marvel at the stands of saguaros massed on southern-facing slopes, or the expanses of wildflowers after sufficient fall rains. We are in awe of the resilience of the trees, shrubs, and cacti that flourish on only 12 inches of rainfall per year, and we enjoy in the intoxicating fragrance of creosote and bursage after a monsoon rain. Why is it then, that people eradicate the desert plants that flourish around their home, replacing them with plants from the Mediterranean, Asia, South America, and other continents? Our lust for exotics comes with a high price to the birds and animals that depend on native plants for food and cover.

Take a guess at what percentage of vegetation cover in urban Tucson is native. Only 10 percent, believe it or not. The showy birds of paradise and mounds of yellow lantana that are staples in developed landscapes originate in Central and South America. People are drawn to the bright flowers and longlasting blooms, ignorant or uncaring of the fact that these plants have little value for our native wildlife (nectar-seekers visit the flowers, but the plants do not support the larvae of the pollinators). Fountain grass, produced in a multitude of varieties by the nursery industry in response to consumer demand, now choke nearly every watershed in the valley. African sumac, a tree popular due to its lack of thorns and evergreen appearance, clogs our washes, displacing native riparian and xeroriparian plants.

Non-native species also are introduced for erosion control and animal forage. Buffelgrass — now wreaking havoc with our Sonoran Desert ecosystem and carrying fire into areas that are not fire-adapted (saguaro cacti do not recover from burning) — was introduced by the U.S. Soil Conservation Service in the 1930s. Due to its drought tolerance, high seed production, and ability to withstand heavy grazing, it was determined to be a perfect candidate to hold soil in place and feed a growing cattle population. What could possibly go wrong?

The American Bullfrog was stocked in our watercourses for sport hunting through the early 1980s. Today, the bullfrog eats its way through native populations of fish, frogs, turtles and gartersnakes. Non-native fish that have been stocked in our lakes wreak havoc on our native amphibian species. Save the bees? It is the hundreds of species of native bees we need to save. The introduced European honeybee consumes enormous amounts of pollen and nectar, leaving that much less food for native insect, bat and bird pollinators. To boot, the European honeybees are less effective pollinators of our native plants – so they take the pollen, but don’t do the plant any reproductive favors.

Why don’t our native species successfully compete with invasives? An introduced plant that becomes invasive here is not invasive in its place of origin. Introduced plants often lack predators that keep them in check in their home range. In their new environment, they may exhibit characteristics such as early flowering, abundant seed production, and rapid vegetative growth that catapult them to the top.

Native animal species are highly correlated to native vegetation. The presence of thorny desert scrub plants such as desert hackberry and catclaw acacia is associated with the presence of ash-throated flycatchers, Gambel’s quail, northern cardinals, and verdins. Desert scrub plants provide great foraging (they host a variety of insects), protection (due to thorns and density) and nesting sites. Every non-native plant takes the place of a native that could be providing food and habitat. Retention of native wildlife species requires retention of native vegetation – it is that simple.

Barriers to Survival

Pull up Google Earth and look at the landscape between Arizona and Mexico. This land, in the heart of the Sonoran Desert, is a tapestry of mountain ranges flowing between Tucson and Hermosillo. These Madrean “Sky Islands” provide an incredible diversity of elevation and species. American biologist/naturalist/author E.O. Wilson lists the Madrean Archipelago as one of the “best places in the biosphere.” Conservation International calls it a “biodiversity hotspot.”

This area also is becoming a “last-stand” for numerous environmental issues. The border wall, the Rosemont Mine, and the proposed Villages at Vigneto are hotly contested in part because they are threatening one of the last still relatively wild places in Southern Arizona and beyond into Mexico.

No matter how you cut it, or what your politics, the border wall will limit movement of plants, animals, and natural drainage in addition to people; the mine will open a huge hole in the ground and bury a canyon; and the Villages will add 100,000 new residents to the Benson area. All three will have serious implications for the water table, native vegetation and wildlife.

At a height of up to 30 feet, bollards tightly spaced and supported with massive footings reported to be up to 3 feet wide and 10 feet deep, the border wall is a formidable barrier. With longer ladders and deeper tunnels, humans will assuredly breach the wall, but wildlife and native flora likely will not. With the wall comes a 60-foot cleared no-man’s land on either side. Lit up and frequented by border patrol vehicles, the lights, noise, and absence of vegetative cover are a kind of barrier. In addition to the roads along the wall, border patrol has blazed a network of roads and trails through the desert, including through Organ Pipe National Monument. Disturbed soils, roads and vehicle tires are conduits for invasive species, bringing another environmental threat to this embattled area.

Serraglio explains that the wall is a barrier for more species than we might think. The ferruginous pygmy owl, still surviving in these borderlands after being extirpated from urban Tucson, is unlikely to breach a wall of this height. Pygmy owls tend to fly low to the ground. They, like many other birds, also prefer areas with vegetative cover that allow them to hide. The question is not whether they could fly over the wall, but whether they would. The wall will likely further divide the owl population, creating smaller sub-populations that are more susceptible to extinction.

People use a lot of copper. Copper is essential for making and powering the multitude of devices we can’t live without. Copper deposits are finicky, their locations pre-determined and not necessarily in locations advantageous for extraction. In the case of Rosemont, the concentrated copper deposit is in the heart of the already besieged, ground-water-thirsty Cienega Creek Watershed. The mine would cover 4,400 acres, and include an open pit 3,000 feet deep and more than a mile wide. The footprint includes roughly 2900 acres of piled waste rock and tailings placed at the headwaters of Davidson Canyon, which flows into Cienega Creek.

Water use at Rosemont is estimated to be 5,000 acre-feet per year. The mine will pump groundwater to meet this demand. To offset the extraction of groundwater, CAP water is being banked and proposed to be piped and pumped to recharge basins within the Cienega Creek watershed to offset the demand.

The only way to reduce the need for copper mines is to reduce the demand for copper. And that gets back to the numbers of humans on the planet. For those of us who enjoy modern conveniences, it might be time for us to step up and know our copper mine. It is obvious the Rosemont site is fragile and deserves protection. But what about all the other mine sites in Arizona, the U.S., and other countries?

Sprawling across 13,000 acres of undisturbed grasslands between the Whetstone Mountains and the San Pedro River, The Villages at Vigneto promises to bring 28,000 homes, 100,000 new residents (almost doubling the current population of Cochise County), five golf courses, and retail and commercial centers over the next 20 years.

Vigneto sits one valley east of the proposed Rosemont Mine. The San Pedro River, dubbed “the last free-flowing river in the Desert Southwest” meanders to the development’s east. The river’s flow has been reduced over the last 100 years due to the influx of humans and resulting increased well drilling and groundwater pumping. Today, stretches of the San Pedro only flow intermittently, in response to rainfall. The average depth of a well drilled today is 150 feet deeper than a well drilled 50 years ago.

Many of the endangered and threatened species described earlier in this article exist in the San Pedro River basin area, dependent on the stretches of perennial water. Like the mine, the Villages pit those trying to preserve the state of the terrain against those who preach the benefit of economic development, new jobs, better schools, and ways to keep local kids from leaving Benson after graduating.

Just how much water would 100,000 new residents use? A typical four-person household uses about one-third of an acre-foot, or around 108,000 gallons of water per year. For the estimated residents at the Villages, this adds up to 8,286 acre feet per year (household water use only), or approximately 65 percent more than the Rosemont Mine would use in each one of its 19 years of operation.

Nurturing the Wild

Most people — even miners and developers, and regardless of political party — love the wilderness. We are part of nature, and there is something about the bleating call of the spadefoot toad during the summer monsoon, the knowledge that jaguars still roam the mountains, and the ability to gaze out at a desert horizon, unbroken by houses or humans, that thrills us.

So how do we reconcile meeting our human needs with preservation of sufficient habitat to keep the wild wild? Ecologists and conservationists have been discussing this concept for decades. Wilson, a biologist, author, and passionate proponent of the preservation of biodiversity, proposes Half- Earth — the setting aside of “half the land and sea to safeguard the bulk of biodiversity, including ourselves.”

Michael Rosenzweig, ecologist and former Director of Tumamoc Hill in Tucson, authored “Win-Win Ecology” in which he details how economic activities such as mining, development, and agriculture can go hand-in-hand with the conservation of species. Rosenzweig states that, ”Right now, our footprint is too big. Going barefoot is not the answer but the time has come to trade in our jackboots for the grace and elegance of ballet slippers.”

What Wilson and Rosenzweig are saying is that we cannot take wildlife for granted. Human impact, while always large, has become so enormous that the rest of nature is forced out at every turn. It isn’t some distant rain forest that is threatened, it is our home here in the desert.

Carolyn Campbell

Carolyn Campbell at the Sweetwater Preserve.

Carolyn Campbell is the Executive Director and founding member of the Coalition for Sonoran Desert Protection, an alliance of 30 conservation and neighborhood groups working to preserve connectivity between mountain ranges, along watercourses, and through urban areas. In the spirit of “win-win,” the Coalition’s stance has been to focus development in less environmentally sensitive areas rather than protest it all together. When I ask how she stays optimistic in light of the habitat loss that is occurring, she lists the many positive impacts made with the support of the Coalition. These include the construction of the first wildlife overpass in the Sonoran Desert, crossing over Oracle Road in Northwest Tucson, the upcoming construction of an overpass on State Route 86 near Kitt Peak to accommodate bighorn sheep movement, and the championing of the 2004 open space bond that allowed for the protection of more than 200,000 acres of open space.

“Well that’s the only way I can keep going because there have been so many victories,” Campbell says. “Sometimes I think of it as you have to get really high when you have a success and you can’t get too low when you have a little defeat.”


Carianne Campbell

Thanks to packrats and the preserved biological artifacts in their middens, we know a bit of the timeline of this plant migration. As the northern ice sheets and our local pinyon-juniper-oak woodland retreated 12,000 years ago, the desert began its return march north, from where it had been biding its time in the warmer southern regions. Saguaros and brittlebush arrived first after 1,000 years. Two thousand years later the desert scrub arrived. Last to return, 7,500 years after the end of the glaciation, were the legume trees (ironwood and foothills palo verde) and organ pipe cactus, completing the plant community that we recognize today.

How do plants move? Some seeds are spread by wind, others sprout where they fall, and many plants rely on animals to carry their seed. Seed may get caught in the fur of a coyote, or be ingested and carried by a bird, deposited far from its origin. The survival of plants and animals are intertwined, and the ability to move freely and adapt to changing environments is critical.

Carianne Campbell, owner of Strategic Habitat Enhancements, is a restoration specialist, working in wild and urban landscapes in the Southwestern U.S. and Northwestern Mexico. She has been involved with projects of vastly different scales and notes that, “It is possible to make a difference for native plants and wildlife in small urban spaces. These areas — especially when linked together — can provide a refuge for many native species even when wildlands are suffering.”


Since 1900, human consumption of copper has risen times 50. Copper plays a ubiquitous role in our standard of living: energy, transportation and electronics. As the rest of the developing world aspires to the same standard, copper use will increase.



World copper mine production in 2018 was 20.6 million tonnes (metric tons).

Raw copper consumption in the U.S. in 2018 was 1.8 million tonnes.

Arizona is a copper state; 66 percent (0.8 million tonnes) of the annual U.S. copper production is mined in Arizona. There are 12 copper mines currently active in the state, and nine new mines are slated for production.

Over its 19-year life, Rosemont is expected to produce 1.9 million tonnes of copper, or enough to build 9.5 million single family homes, or about six years of homebuilding in the U.S. at today’s rates.

To convert the non-renewable based portion of the U.S. power grid to solar, ignoring the additional resource requirements of battery storage, would require 5.5 million tonnes of copper.

To convert the non-renewable based portion of the U.S. power grid to wind, ignoring the battery requirement, would require 3.9 million tonnes of copper.

To swap all internal combustion passenger vehicles in the U.S. with electric ones would require 21.5 million tonnes of copper.

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