Where did they come from? Why are they such a serious threat? Can anything be done to control them?

A R I Z O N A - S O N O R A D E S E R T M U S E U M

BIOINVADERSof the Sonoran Desert

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xotic. Non-native. Alien.These are just a few of the

terms that have been appliedto the approximately 30,000 foreignplants, animals and microbes thathave taken up residence in theUnited States since Europeans firstset foot on her shores. Many ofthese introduced species havecaused little harm; others havecaused irreparable damage, displac-ing native plants and animals anddisrupting entire ecosystems. Theterm “invasive species” is used todifferentiate the latter group.

How serious is the problem?A study published in 1998 byBioScience magazine reports thatinvasive species constitute a greaterthreat to endangered species thando pollution, overharvesting, anddisease combined; only habitat lossranks higher. Invasive plants, forexample, now infest over 100

million acres in the United States.Three million acres, an area twicethe size of Delaware, is lost to theseinvasive plants each year.

Unlike the kudzu-drapedforests in southeastern UnitedStates, invasive species in theSonoran Desert are less apparent tothe untrained eye. Unfortunatelythey are just as damaging to biodi-versity and ecosystem processes.This special edition of sonorensisupdates some of the informationprovided in the winter 1999Bioinvaders issue of sonorensis,which took a close-up look at howthe invasive species problem is man-ifesting itself in the Sonoran Desertalong with potential solutions.

To achieve success in the waragainst invasive species, we mustmake use of all the tools available tous, such as public policy reform,public awareness programs, and

environmentally friendly controlmethods. Most importantly, wemust form collaborative, inclusivepartnerships that can effectively and efficiently coordinate responsesto a common threat. The joint production of this publication byour respective organizationsrepresents one such partnership.

Richard H. DaleyCEO and President

Arizona-Sonora Desert Museum

Patrick GrahamArizona State Director

The Nature Conservancy

Luther PropstExecutive DirectorSonoran Institute

Vis i t us at www.deser tmuseum.org

IntroductionCONTENTSs o n o r e n s i s

Exotic. Non-native. Alien.

Red bromeSahara mustard

JohnW

iens

1 Introduction

3 Exotic Species: An Introduction Native Species: An Epitaphby Gary Paul Nabhan

6 Controlling Invasive Exotics—The Right Tool for the Jobby Barbara Tellman

7 Salvinia molesta—A Growing Threatto Arizona’s Waterwaysby Barbara Tellman

8 Bullfrogs—The Dinner Guests We’re Sorry We Invited!by Cecil Schwalbe and Phil Rosen

11 The Conservation Dilemma of Non-native Versus Native Fishesby W. L. Minckley

14 The Sonoran Desert’s Ten Least Wanted

16 Plant Stories of the Sonoran Desertby Peter Gierlach

18 Battling Buffelgrass:You Can’t Win If You Don’t Playby Sue Rutman

21 Red Brome and Wildfiresby Jerry Asher

22 Pulling Together:The DesertMuseum Battles a BiologicalWildfireby Patty West and Barb Skye

24 Invasive Plant Managementin the Sonoran Desert: An Updateby Nina Chambers, John A. Hall, and Barb Skye

26 Exotic Grasses andNative Wildlife by Jane H. Bock and Carl E. Bock

28 What Can You Do?

Rick D

aley

T. R. V

anDevender

E

Cover photo of red brome and prickly pear by David W. Lazaroff

This issue of sonorensis was revised and reprinted as a jointpartnership among the Arizona-Sonora Desert Museum, TheNature Conservancy of Arizona, and the Sonoran Institute

to further public awareness and understanding ofinvasive species and their impacts on the nativeplants and animals of the Sonoran Desert.

The publication of this special edition ofsonorensis was made possible by funding

received through The Nature Conservancy of Arizona and the Sonoran Institute from the

Department of Defense Legacy Resource Management Program and the Ford Foundation.

2021 N. Kinney RoadTucson, AZ 85743-8918

7650 E. Broadway Blvd., 203Tucson, AZ 85710

1510 E. Ft. Lowell RoadTucson, AZ 85719

Special Edition • Winter 2002

f you climb Camelback Mountain inPhoenix, then “A” Mountain in Tucson,then the hills behind “Sandy Beach” at

Cholla Bay, Sonora, you will meet someof the same stragglers in all three places—plants and animals which did not occur inthe Sonoran Desert a century ago.Africanized bees may buzz around yourhead, or try to suck up the last bit ofmoisture in your coffee cup. At your feet, and in your socks, you willfind the seeds of several exotic grasses andmustards. Sahara mustard. Red brome.Buffelgrass, or its ornamental kin, foun-tain grass. These relative newcomers to theSonoran Desert can be found in nearby protected areas as well, from thePinacate Biosphere Reserve, to SaguaroNational Park, to the Sierra Bacha, homeof the “boojums” on the Sonoran coast of the Gulf of California.

Whether we walk around in theheart of a desert city, or retreat to themost remote stretches of so-called wilderness in the U.S./Mexico border-lands, it is likely that at least one of 600species of non-native plants and animalscan be found within a few steps of wherewe stand. They are welcoming us to thePlanet of the Weeds.

They are with us today, but are theyhere to stay, as David Quammen worriesthey will be? That depends, of course, onhow honest we are in acknowledging themagnitude of this ecological dilemmaand how diligent we are in our efforts tokeep Sonoran Desert landscapes native.

Few people understand the severityof the current impact of exotics uponnatives in the U.S./Mexico borderlands.The eco-tourist viewing desert wildliferefuges, national parks, biosphere reserves,and nature conservancy areas might wellassume that large tracts of NorthAmerica’s desert wilderness have remainedintact, unaltered by humans. In realitythese desert landscapes have been shapedby thousands of years of human influ-ence. Indigenous cultures dispersed plantsand animals into desert locales far beyondtheir natural ranges; agaves, beans, corn,gourds, chuckwallas, macaws, spiny-tailediguanas, and turkeys are among the manyorganisms which prehistoric inhabitantsof the desert moved and manipulated.Soon after the arrival of Europeans,human impact intensified. Seeds andstems recovered from the adobe walls of early missions prove that Jesuits andFranciscans brought more than bibles,grape vines and bread wheat with themfrom Europe; weed seeds were carriedalong in bags of crop seeds, and in thehooves of livestock.

Many environmental historians havethought that the aridity of deserts pro-tects them, more than any other biome,from the effects of invasive species. Yet wefind considerable evidence to the con-trary: invasive species occur abundantlyin Sonoran Desert habitats, even in areasremote from running rivers and flowingstreams, or from metropolitan or irrigatedagricultural areas. Researcher Ray Turner

notes that MacDougal Crater, near thewestern flanks of the Sierra Pinacate, now hosts Sahara mustard on the craterfloor, despite the fact that grazing andother human-managed activities havebeen negligible there. Punta Cirio in the remote Sierra Bacha has also beeninvaded by this Mediterranean annual,even though it is miles away from agricul-ture. Tumamoc Hill in Tucson, the oldestscientific area free of domestic livestockanywhere in the deserts of the world, hasadded feral dogs, cats, and 52 exoticplants to its biota over the last century,but has lost at least 20 native species—18 plants and 2 mammals—over thesame period, according to researchers Jan Bowers and Turner. Managers haveestimated that as much as 60 percent ofthe vegetative cover of the Sonoita Creek-Patagonia reserve, the first Nature

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Gary Paul Nabhanformer Director of Conservation and Science

Arizona-Sonora Desert Museum

Exotic Species:An IntroductionNative Species:An Epitaph

“Having recently passed the great age of biogeography, we will have

entered the age after biogeography, in that virtually everything will live

virtually everywhere, though the list of species that constitute ‘everything’

will be small.… Earth will be a different sort of place—soon, in just

five or six human generations. My label for that place, that time, that

unavoidable prospect, is the Planet of Weeds.”

David Quammen Harper’s Magazine (1998)

Even remote areas, such as the floor ofMacDougal Crater, near the westernflanks of the Sierra Pinacate, are notsafe from invasive species.

View of a 1994 fire burning in Saguaro National Park. Red brome was probably theprimary culprit.

2Exotic species: An overview

Mer

ritt S

. Kea

sey

Jerr

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sher

Mark D

imm

itt

Breathtaking Sonoran Desert wildflower displays can be threatened by invasive species.

I

signed by President Clinton in early 1999should help implement the strategy.Although Mexico does not yet have such anational agenda, it has an ambitious strate-gy for controlling exotics on the midriffislands of the Gulf of California thatincludes the use of witty and colorfulcomic books to alert fishermen to the perilsof invasive animals. The real need is foragencies in both countries to be “pullingtogether” in the same direction, so that

one agricultural agency is not intentionallyintroducing cold-tolerant buffelgrass strains while another is attempting to eradicate it from a protected area just a few miles away.

We have many questions to answer ifwe are to deal effectively with the ecologi-cal invasions in the region as a whole:

○ Do plants invade agricultural areas first,or roadsides?

○ How do exotic aquatic animals dispersefrom waterhole to waterhole?

○ Are ungrazed desert vegetation patchesless prone to invasions than grazed areas?

○ How do El Niño years fuel the spread ofexotic animals and plants?

○ Do the same control methods work indrought years as in wet years?

We face an even tougher questionwith many severe infestations: Do we needto use controls that carry additional risk,such as chemicals or the introduction ofnatural enemies of the invaders, which arethemselves exotics?

Recently 33 field scientists rankedexotic grass plantings seventh and biologi-cal invasions tenth among the greateststresses affecting the biodiversity of theSonoran Desert region. If these two categories are combined, exotic plantingsand related invasions rank among the fiveworst threats to our biodiversity. It is timeto concede that we are beginning far too late to grapple with a problem of this magnitude, but that starting to deal with it earnestly today is better than never acting at all.

This article is adapted from a chapter by the same name in the future Arizona-Sonora DesertMuseum publication, Invasive Exotic Species in the Sonoran Desert (working title), edited by Barbara Tellman.

A native or non-native species that is unwanted and invasive in a landscape or agricultural setting.

An aggressive species that displacesother species; most commonly a natu-ralized species occupying a disturbedniche, although the most destructiveinvasives also displace natives in intactcommunities.

A non-native species that is reproduc-ing in a new region without help (forexample, irrigation) from man.

One that evolved in one region andwas taken to another distant region byhuman activity where it would not nat-urally have migrated because of somebarrier, such as an ocean. Also referredto as INTRODUCED SPECIES,EXOTIC SPECIES or ALIENSPECIES.

One that evolved in a particular regionor that evolved nearby and migrated tothe region without help from humans.

NATIVE SPECIES

NON-NATIVE SPECIES

NATURALIZED SPECIES

INVASIVE SPECIES

WEED

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Fountain grass along the King Canyon Trail in Saguaro National Park (west unit).

desert mallow

rain lily

African daisy

redstem filaree

Sahara mustard

Conservancy area in Arizona, is dominat-ed by exotics, and that introduced fishpose a recurrent danger to its threatenednative fish. Larry Stevens believes thatinvasives have played a major role in thecontinued loss of one native species peryear from Grand Canyon National Parkover the last two decades.

A high proportion of NorthAmerica’s micro-areal endemics, that is,unique plants and animals with restricteddistributions, occur only in deserts.Invasive species endanger them. On themidriff islands of the Gulf of California,where endemism is highest in the region,Eric Mellink found that feral rats and catshave already threatened several smallmammal and nesting bird species. TheBaja California peninsula, also rich inendemics, is under conversion to buffel-grass pasture just as Sonora is, but on thepeninsula this grass’s escape into adjacentareas threatens many more natives withrestricted ranges. Other areas rich inendemism—the oak woodlands of “skyislands,” the cienegas of the DesertGrasslands, and the oases of SonoranDesertscrub—are also vulnerable to mass extinctions as a result of accidentalintroductions.

While competition with natives isusually given as the blanket reason forwhy exotic species are “bad,” their ecolog-ical impacts vary widely in effects andmagnitudes. Some invasive species such asred brome, Lehmann’s love grass and buf-

felgrass compete with natives for groundsurface, soil moisture, and nutrients, butthey also alter fire regimes and nativeplant regeneration patterns. Tamarisks notonly compete for space and water inriparian habitats, they also disrupt streamflows, especially during flood stages.

Secondarily, these altered regimesmay reduce resources for migratory polli-nators and insectivorous waterfowl, there-by having a ripple effect throughoutentire regional landscapes. In short, theecological impacts of invasives are diverse,from cowbird predation on eggs to giardiainfestations in vertebrate guts.

If most invasive species are so disruptive to the health and productivityof native biotic communities, what can bedone about them? The answer is complex,and we need to consider both short-termand long-term causes of habitat change.Whatever actions we take should certainlylink prevention, education, detection,control, restoration, and monitoring. Thelocation of the Sonoran Desert within the

U.S./Mexico border region challenges usto detect species moving both ways acrossthe international boundary. Althoughubiquitous species such as tropical whiteflies and tumbleweeds cannot be stoppedat the border, it may be possible to slowthe intentional introduction of additionalexotics by informing importers and bor-der customs officials—as well as the pub-lic in general—of the high long-termcosts of casually-introduced invaders.

The message needs to reach a wideraudience. The Arizona-Sonora DesertMuseum conference on the subjectreceived front page coverage in Tucsonnewspapers, as well as a follow-up Sundayeditorial entitled, “Beware TheseInvaders.” It appeared that science jour-nalists in southern Arizona were astound-ed by how little they had known aboutthe economic costs of bullfrogs, carp,tumbleweeds and tamarisks. The problemwas called “a subtle, late-breaking andquietly astonishing crisis of ecologicalidentity.” Many Arizonans learned forthe first time that invasive plants and animals are among the top threats toendangered species and biodiversity globally, and by some accounts, thegravest threat to desert diversity.

In a positive initiative known as “Pulling Together,” private and public U.S. organizations joined forces to map out and endorse a national strategy for dealing with invasive plants.An Executive Order on Invasive Species

Steve Phillips

Mammals 6Birds 7

Reptiles & Amphibians 13

Fishes 57

Invertebrates 179

Plants 232

Number of Exotic Species of Various Taxonomic GroupsEstablished in the Sonoran Desert

In a positive initiative known as

“Pulling Together,” private and

public U.S. organizations joined

forces to map out and endorse

a national strategy for dealing

with invasive plants.

5Photos, top to bottom: Al Morgan, Steve Phillips (lily and daisy), David Lazaroff, John Wiens

he first line of defense in controllinginvasive exotics is to not let the invasion start. Don’t let potential

invasives in and if they do invade, eradicatethem immediately. The U.S. Departmentof Agriculture spends millions of dollarseach year to keep plants and insects fromcrossing the border; but even so, many newspecies are brought into the country eachyear accidentally or on purpose. Some ofthese thrive at the expense of natives,resulting in infestations such as the bull-frogs in many ponds and cienegas, andbuffelgrass in Sonoran thornscrub. Areinvasive exotics completely out of control?In some cases the answer is probably “yes,”but we can still manage a good many ofthem, even if we can’t eliminate them com-pletely. There is, however, no one solutionthat will solve all the problems.

Basically, we have several choices:

○ Remove them manually or by machine.These methods are usually very labor-intensive and sometimes result in evenmore plants if they resprout from theroots or grow from fragments.

○ Remove them with chemicals. Use ofchemicals can be risky unless they arefirst proven harmless to desirable speciesand without long-term effects.

○ Use other species (natural enemies) toremove problem species—“biocontrol.”Because the new species may themselvesbecome problems, biocontrol is nowstrictly controlled in the united States.

The control agent must harm only thetargeted species. Extensive trials arerequired. An advantage of biocontrol isthat the change occurs gradually, allowingtime for natives to replace the exotics.

○ Interfere with their reproduction. Thesemethods have reduced numbers of white-flies after sterile males were released. Theyhave also successfully yielded sterileyoung in exotic fish species.

○ Change land management practices toencourage native plants at the expenseof exotics. Many exotics only thrive insituations where human disturbance hascreated ideal conditions for them. Whendisturbance is reduced, natives may beable to compete successfully.

None of these methods carry 100percent guarantees, nor are they totallyrisk-free. Often it takes a combination ofmethods to do the job, along with a lot ofmoney and/or a lot of volunteer hours.Often repeat treatments are needed.

While there are some cases wherecontrol has been tried and has not succeed-ed, we do have some success stories in thisregion. The projects described in this issueby Sue Rutman and by Cecil Schwalbeand Phil Rosen are good examples of thechallenges and initial signs of success.

Some other examples:

○ At The Nature Conservancy’sHassayampa Preserve volunteers cutdown tamarisk (saltcedar), then treat it

with chemicals to prevent regrowth.While there is still some tamarisk at thepreserve, the targeted areas have beenkept relatively free of it, allowing thenative cottonwoods and willows toresprout in this relatively natural stream.

○ In Sabino Canyon the Arizona Gameand Fish Department and the U.S.Forest Service cooperated to eliminateexotic green sunfish from a three-milesection of the creek in order to improveconditions for native fish. They electro-shocked the stream so that they couldcatch the native chubs and move themto a safe area, then dosed the creek witha fungus-derived substance that targetsgill-breathing creatures. The sunfish aregone and other creatures such as frogsand turtles suffered no ill effects. A second treatment should ensure complete eradication.

○ At The Nature Conservancy’s RamseyCanyon Preserve, an introduced land-scape plant, Vinca major, dominatedmany areas along the creek. Volunteers(especially one dedicated local resident)systematically uprooted plants. Nativeplants have begun to recolonize manyareas, but planting will be also be needed. Uprooting was not successful in rocky areas where the entire root systems couldn’t be removed.

○ Removal of livestock that grazed along a portion of the middle San Pedro River brought about a reduction in the number of saltcedar trees.

Controlling Invasive Exotics—The Right Tool for the Job

Controlling invasives

Salvinia molesta–A Growing Threat to Arizona’s Waterwaysn aquatic fern from South America has land managers in

our region alarmed. Sold bynurseries for use in ponds, Salviniamolesta has now invaded the lowerColorado River. It grows rapidly evenfrom tiny fragments of the plant, andunder the right conditions it candouble its mass in one to threeweeks. It can survive in any watersthat do not freeze over.

Salvinia forms floating mats upto two feet thick that block sunlightand oxygen, causing problems andeven death for a variety of aquatic

life. Labeled the world’s worst weedin the Guiness Book of World Records,Salvinia is a major problem in India,Subsaharan Africa, South-east Asia,and from the Southeast UnitedStates into Texas. The greatest imme-diate concern here is for the wildliferefuges vital to waterfowl along thelower Colorado River. Managers alsofear that the weed will migrate toother rivers, lakes, stock ponds, irri-gation systems, power plants, andcanals. Recreational boats present thegreatest potential for rapidly spread-ing Salvinia along the Colorado

River and to other waterways.There is no easy way to remove

it. Herbicides, biocontrol, manualremoval, and drying up the waterbody are the main choices. Since theplant grows among other vegeta-tion—cattails, willows, and saltcedar,for example—it is difficult to spraychemically or remove manually, andthe proposed herbicides damage anyvegetation they touch. Biocontrolwith a weevil that only destroysSalvinia has been successful else-where, but there is concern aboutintroducing another exotic species.

Water removal is an option for smallponds or canals, but not for theColorado River. Besides, even afterthe plant has dried it can recoveronce water is again available. Most ofthese control tactics require permits;obtaining them can be a long andsometimes difficult process.

An interagency task force isconsidering options. Meanwhileavoid spreading it with your ownwatercraft, and if you sight the weed, please report the location to the U.S. Fish and Wildlife Service, (602) 640-2720.

by Barbara TellmanWater Resources Research Center

The University of Arizona

by Barbara Tellman

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○ On the other hand, The NatureConservancy used controlled grazingto manage exotic Johnson grass atthe Sonoita-Patagonia Preserve.They are replanting the area withnative sacaton grass. Although theyinitially used fire to control the

Johnson grass, it thrived on fire,coming back better than ever.

Although there is hope of controlfor at least some infestations, theprospects for controlling others are limited, and the costs are generally high.Prevention is still the best approach.

Volunteers removing tamarisk at The NatureConservancy’s Hassayampa River Preserve.

Salvinia molesta (both photos)

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every time they flee. Leopard frogs don’tsquawk when fleeing; they also differ inhaving light-colored ridges running downeach side of their backs and “leopardspots” surrounded by light halos. Bull-frogs are most commonly green, but colors vary widely, from olive to bronze tobrown, sometimes with spots resemblingcamouflage clothing. Adult males sportbright yellow throats and conspicuouseardrums (much bigger than their eyes).Bullfrogs range from three-gram pipsqueaks to one-kilogram, eight-incheating machines.

Our struggles to eliminate bullfrogsover the past decade and a half havetaught us hard lessons. Bullfrogs seemimpossible to remove from complex wet-lands. Our hunting pressure producedwary frogs; we could not approach within50 yards of some frogs before they left thewater and sought refuge in pack rat nests.Merely launching a canoe spooked frogsout of a pond and into the adjacentmarsh. Our intensive hunting and trap-ping efforts did reduce adult populationnumbers by 90 percent or more duringthe summer, but within a year, dispersaland rapid growth of young frogs almostrestored adult population numbers.

Bullfrogs are extremely prolific, pro-ducing up to 20,000 eggs per clutch, fiveto ten times that of their native cousins inArizona. Bullfrog tadpoles may also out-compete tadpoles of other true frogs.Additionally, unlike leopard frog tadpoles,

they are distasteful to fish, which givesbullfrogs a great advantage now thatintroduced predatory fishes are all overthe Southwest.

Unlike fish, bullfrogs travel overland, a factor complicating their removal.On a night with summer rain, we com-monly see small bullfrogs a quarter to ahalf mile from their ponds. At BuenosAires National Wildlife Refuge this pastsummer, frogs traveled as far as two milesfrom the “home” pond, and we foundevidence suggesting that dispersal four to five miles is likely.

Bullfrogs eat any prey they can getinto their very large mouths, using theirfront feet to shove large items into theirgullets. They most frequently eat inverte-brates. Interesting stomach contents haveincluded tarantulas, beetles, moths, centipedes, scorpions, dragon and damselflies, and toe biters (the three-inch longpredacious true bugs that have beenobserved eating small frogs). One frog,apparently with a penchant for spicyfood, had three tarantula hawks (largewasps that supposedly pack the mostpainful sting in the Southwest) in his stomach.

By weight, vertebrates play a majorrole in bullfrog diets. We found represen-tatives of every non-marine vertebrateclass in their stomachs. Some more spec-tacular items include a cotton rat, severalother rodent species, bats, a nestling Red-winged Blackbird, Common Yellow-

throats (warblers), alligator and lesser ear-less lizards, Mexican and checkered gartersnakes, western patchnose snakes,Sonoran mud turtles, leopard frogs, andthreatened native fish. Even small bull-frogs can be fearsome predators on vertebrates. The smallest bullfrogs eatmany small fish such as topminnows and chubs—probably because the small

fish frequent the same shallows—but the numbers of fish taken by bullfrogs still doesn’t impact fish populations significantly. A 1.75-ounce bullfrog, atonly half its weight at maturity, can easilyeat newborn garter snakes or small lizards.The bullfrogs that had eaten bats werepost-adolescents weighing about 3.5ounces each. That supports observations

8

Bullfrogs—The Dinner Guests We’re Sorry We Invited!

eeek! Splash! A bullfrog hits the water. This sound, while a fond memory of our childhood hikes elsewhere, is now

a clarion call to battle in a war that our nativefrogs, and even garter snakes, are losing to ahost of introduced aquatic predators.

All six native species of true frogs inArizona have suffered large losses since theearly 1970s, with four in danger of disap-pearing from the state, and one alreadygone. The lowland leopard frog (Rana yava-paiensis), still common in central Arizona,has disappeared from southwestern Arizona,California, and New Mexico. The Mexicangarter snake (Thamnophis eques), in direstraits in the U.S., and the declining narrow-headed garter snake (Thamnophisrufipunctatus) of central Arizona are bothaffected by introduced species.

Wetland loss was important in thedecline of our native frogs, but the majorcurrent problem is non-native aquatic preda-tors (fishes, crayfish, and the bullfrog Ranacatesbeiana) from the eastern U.S. andEurasia. Add newly discovered frog diseasesto the mix, and the threats to native frogsthroughout the American West are daunting.

We became acutely aware that therewas a bullfrog problem while surveying theMexican garter snake in 1985-86. At SanBernardino National Wildlife Refuge, eastof Douglas, we found bullfrogs superabun-dant. The Mexican garter snakes consistedalmost entirely of adults too big for bull-frogs to eat, yet most of the snakes had frog-chomped tails. Leopard frogs, common at

this refuge as recently as 1981, were reduced to a single site—too shallow forlarge bullfrogs—from which the leopardfrogs disappeared during a drought in the late 1980s. Initial efforts to control bullfrogs allowed young garter snakes time to mature into adults, but these effects were not permanent.

The bullfrog’s natural range stretchedfrom Florida north to Canada, and west toNew Mexico, but it is now established inevery western state. Before 1900 the bull-frog was spread as a food and game animal.It thrives in deep, permanent, relatively stillwaters, most often found here in man-madeponds, lakes, or slow-flowing streams. Theabsence of its natural predators—especiallysnapping turtles and large water snakes—has helped it flourish. Arizona’s garter snakesrelish small bullfrogs, but large bullfrogsturn the table, eating juvenile garter snakes.

The bullfrog is the only frog or toad in Arizona that squawks when it leaps tosafety—often setting off a mass bullfrogexodus—though all bullfrogs don’t call

Cecil SchwalbeU.S. Geological Survey, Biological Resources Division

and Phil RosenDepartment of Ecology and Evolutionary Biology

The University of Arizona

All six native species of true frogs

in Arizona have suffered large

losses since the early 1970s, with

four in danger of disappearing

from the state, and

one already gone.

Bullfrog DamageBullfrogs have almost eliminated the Mexican garter snake from the San

Bernardino National Wildlife Refuge. The snakes remaining are almost all old,large females, with tails chewed by bullfrogs (inset).

Bullfrogs

This bullfrog swallowed another of itskind. Bullfrog cannibalism in Arizona

allows population densities up to 30times those reported from the bullfrog’snatural range in eastern United States.

Julia

Ros

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Cecil Schw

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Phil

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W. L. MinckleyDepartment of Biology

Arizona State University

hen the Spanish arrived, thepristine Sonoran Desert region

had little surface water and relatively few fishes, with at most only 36 species within Arizona’s present borders. Far more water is impoundedtoday in reservoirs and the number ofspecies has soared! About 80 species, morethan 50 from elsewhere, now swim inArizona waters. Of the original 36, only 6 species persist throughout much of theirnatural ranges. One is extinct, 12 areendangered, 7 threatened, and 10 are of special concern. Although 8 of thethreatened or endangered species survivein adjacent states, they have vanished from Arizona.

Early in this century large dams wereconstructed and canals built for waterdelivery, disrupting natural habitats. Carp, buffalofish, and catfish were stockedas foodfish before the 1920s. Human

populations skyrocketed during and afterWorld War II, increasing demands forsportfishing. By 1960, at least 20 exoticfishes were already established. In the1950s and 1960s non-game species wereremoved so that gamefish could morereadily colonize. Fish toxin was applied tohundreds of miles of western rivers beforediverse trouts, basses, and catfishes wereplanted. A few exotic species arrived acci-dentally with gamefish shipments, whileothers, such as guppies, descended fromdiscarded store-bought pets. Some specieswere planted to control noxious insects or plants; shad and minnows were stockedas food for gamefish or proliferated fromdiscarded bait. Ever-larger predators—flathead catfish, northern pike, walleye,and striped bass—were imported andstocked. People moved some illegally tobring them closer to home. The intro-duced species spread through canals anddesert streams stabilized by dams, artificialhabitats which were to their liking, andmany invaded natural streams from newcenters of abundance, impacting nativefish populations.

Why were exotics promoted andnatives ignored or exterminated? First,government policy was to spread the“most desirable” fishes, mostly easternspecies, throughout the nation. Second,most immigrants were from easternUnited States and preferred the familiarspecies they knew from home overnatives. Finally, management agencies

continued experimenting. If public inter-est waned or a stock declined, a “new”kind was planted; interest in noveltiesraised license sales.

Habitat destruction and alterationare often blamed for native fish disappear-ance. Clearly, as habitats dry, become polluted, or are otherwise made uninhab-itable, fish die and species’ ranges arereduced. Alterations such as temperaturechanges brought about by diversions anddams, and from watershed damage fromgrazing, logging, and road-building mayalso cause declines. Structures blockmigrations, a change to colder water stopsreproduction by warm-water species, andstreams are degraded by increased runoffand erosion from barren hillsides. Just ascertain, however, is the fact that whenexotics appear, as they invariably do inreservoirs or other stabilized habitats,native species decline, then vanish.

Among problems facing nativeswhen exotics are present, predation seemsmost important. Carp, basses, sunfishes,catfishes, and other non-natives eat eggsand juveniles of suckers and chubs. Eventhough long-lived native fishes can persistfor decades, too few young survive toreproduce, so populations disappear whenold fish die. Alien mosquitofish eat babytopminnows and shred fins of adults,making them vulnerable to infections.Brown and brook trouts eat native troutswhile also competing for space and food.Furthermore, rainbow trout, planted in

by Arizona Game and Fish personnel andour field crew that bullfrogs seen jumpingout of the water to catch bats on the wingwere young adult frogs, not extremelylarge ones.

Surprisingly, bullfrogs’ most com-mon vertebrate prey is other bullfrogs.On several occasions, we found a bullfrogwithin a bullfrog within a bullfrog. AtArivaca Cienega we once witnessed amedium bullfrog swallow a smaller one,and then get swallowed by a larger bullfrog, all within a two-minute timespan. We only half-jokingly refer to

bullfrogs as the “great white sharks ofArizona’s waters.”

The absence of natural predatorsand the many abilities of bullfrogs have permitted them to dominate numerous perennial wetlands in the West.Cannibalism enables bullfrogs to remainmore abundant than their base of preyspecies would allow. Some of our studyponds had an adult bullfrog every twoyards along the bank watching for move-ment of any potential food item. Adultpopulation densities are abnormally highhere—10 to 30 times those reported elsewhere. Leopard frogs, young gartersnakes, or baby mud turtles have almostno chance of surviving in the waters of bullfrog-dominated ponds.

Clearly extraordinary measures are needed to eradicate bullfrogs fromaquatic systems (see sidebar at left) andgive native frogs, Mexican garter snakes,and other bullfrog prey items a fighting chance.

The Conservation Dilemma of Non-native Versus Native Fishes

HOW DO WE GET RID OF THESE UNWANTED GUESTS?

In 1999 we started a leopard frog conservation project on Buenos AiresNational Wildlife Refuge (BANWR) in the Altar Valley west of Tucson. We neededto rid the stock ponds of bullfrogs before attempting to reestablish native Chiricahualeopard frogs. Because BANWR is much drier than the San Bernardino refuge, wecontend with much simpler aquatic systems there. However, eliminating bullfrogseven from individual stock ponds with no extensive springs or marshes still requireda combination of techniques.

Fencing (to exclude or contain bullfrogs), drying of ponds, manual removal,and chlorination (to eliminate tadpoles or frogs hiding in the mud of drying ponds)seemed to be effective in eradicating frogs from five of six ponds on the refuge dur-ing this past summer. We will not know how effective those removals were until were-survey the ponds next May and June. Attempting to remove bullfrogs anywhere islikely to take substantial efforts for some years, perhaps a decade or longer, and willrequire bullfrog-free buffers of at least several miles. The importance of livestockponds as habitat for the threatened Chiricahua leopard frog warrants vigorous efforts to develop and maintain bullfrog-free stock ponds on both sanctuaries andworking ranches.

The absence of natural

predators and the many

abilities of bullfrogs have

permitted them to dominate

numerous perennial wetlands

in the West.

Some native fish recovery efforts appear tobe working. For instance, reintroductions of

Gila topminnows have almost doubled thenumber of sites where they live.

A bullfrog exclosure fence around leopard frog ponds. Bullfrogs areso adept at climbing that exclosure fences must have eaves.

Chiricahua leopard frogs were eliminated from the San BernardinoNational Wildlife Refuge by bullfrogs and drought. They now arefound on the refuge only inside bullfrog exclosures.

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health agencies to suppress insects is acase in point. Mosquitofish are advertisedin the public media as available onrequest for pickup or delivery. Such stock-ing violates ESA rules against “take” if theknown predator is planted with topmin-now, perhaps even if the introductionresults in later invasion of topminnowhabitat. A conservation-minded citizenmight easily contaminate a topminnowrefuge by mistake. Who would then beresponsible? Other problems exist, exam-ples being a lack of agency emphasis onnative fishes in the controversial SanPedro River and exclusion of theColorado Delta in Mexico from imperiled-species plans.

The ESA has been manipulated,amended, and indicted, but it remainsthe most significant environmental lawyet enacted. Funding to conserve nativefishes is mostly from development agen-cies, industry, and conservation groups,sometimes under pressure to comply withthe ESA, but often voluntarily. Manyconcerned people are confident thatenough is known to perpetuate most

Sonoran Desert fishes, but support fornew or revised conservation legislation isimperative if progress is to continue.

Finally, native fish survival dependson human wants, needs, and understand-ing. Explosive growth in human popula-tions is placing ever-greater demands onthe environment. And most human resi-dents are new to the desert, with littleunderstanding of resource limitations and certainly no idea that the familiartrouts, basses, catfishes, and other fishesthey caught elsewhere as kids are not natural here.

Thus, education is sorely needed.Differences between natives and non-natives and contrasts between naturaland artificial aquatic systems must bemade clearer, and the roles and impor-tance of native species better communi-cated. Life underwater is largely out ofsight, thus out of mind. The growingpublic desire to perpetuate wildness and wilderness must be extended underwater if native fishes are to remain part of our Sonoran Desert biotic heritage.

A green sunfish removed from Sabino Creek.

essentially all cooler waters, hybridizewith native trouts to swamp them geneti-cally. Moreover, non-native fishes carryalien parasites; an Asiatic tapeworm ispresently spreading among natives, withunknown effects.

Since all native fishes tested so far do well in artificial waters without exotics,many indict non-native fish species astoday’s greatest deterrent to conservingour native species. Along with exotic fish-es, other aliens including plants, crayfish,clams, snails, and bullfrogs, are provingjust as dangerous.

Agencies charged with promotingnon-native gamefish that impact natives,for which they also are responsible, have ahard time doing both jobs. The U.S. Fish& Wildlife Service (USFWS) administersthe Endangered Species Act (ESA) forfreshwater fishes. All federally funded programs fall under the ESA, so westernstates that depend heavily on USFWShatcheries and funding are automaticpartners, and managing fish resources ismostly their responsibility. State agenciessometimes resent federal control to adegree, and they may find little publicsupport for non-game species. TheUSFWS has problems too. After all, itwas instrumental in establishing non-native fisheries and helps maintain them.Now it must persuade development agen-cies, industry, sportfishing groups (thenation’s most influential conservationists),and others to implement the ESA and

protect native fishes as well. Despite all this, progress is being

made. Recovery efforts are underway andsome are working. Naturally spawnedrazorback sucker larvae were captured,grown in predator-free ponds, then repa-triated when they were too large to beeaten. Soon, young adults were reproduc-ing with old ones, so a life-history linkagewas re-established. Reintroductions oftopminnows have almost doubled thenumber of sites where they live. Otherspecies too rare to manage in naturalhabitats are grown in hatcheries for rein-troduction, or held there as stock for the future.

Here rises the dilemma. Non-nativesimpact natives in so many ways that onlyone solution seems to exist to ensurenative species’ survival — remove non-natives or provide habitats from whichthey are excluded. But exotics already areso wide ranging that total eradication isimpossible, and furthermore, connectionsthrough canals, along with non-natives’invasiveness, make exclusion difficult atbest. But isolation is possible. Exotics canbe removed by the same chemical methodused in the past to clear the way forgamefish. Stocks of imperiled natives,genetically pure trouts, for example, arethen reintroduced. Now such efforts torenovate streams are being extended tobenefit native warm-water species, mostrecently at Bylas Springs and in Sabinoand West Turkey creeks, Arizona. Barriers

such as artificial waterfalls are installedafter renovation to stop invasion or reinvasion by non-natives. “No-fishing”rules and bans on transport of live fish or use of live baitfish are designed to stopreintroduction.

All these changes in regulationsrequire cooperation among conservationauthorities, land managers, and privatelandowners, and reflect a positive changein attitude toward native fishes. A num-ber of places are set aside for native fishconservation; Aravaipa Canyon, SanBernardino-Leslie Creek NationalWildlife Refuge, Canelo Cienega, andWest Turkey Creek are some examples in Arizona. But even in such refuges,invasive exotic species remain major problems.

This is not to say that attitudes andpractices have turned around entirely.Continued use of mosquitofish by public

Exotic green sunfish removal project in Sabino Canyon. The stream is being electroshocked so that native chubs can be removed before eradicating the sunfish.

Will Hayes, Arizona Game & Fish Department12

Native f ishes

U.S. Bureau ofFisheries deliverycar and fish-deliv-ery truck. ArizonaGame & FishDepartment photo,ca. 1918.

Non-natives impact natives in

so many ways that only one

solution seems to exist to

ensure native species’ survival

— remove non-natives or

provide habitats from which

they are excluded.

Will H

ayes, Arizona G

ame &

Fish Departm

ent

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THE SONORAN DESERT’S TEN LEAST WANTED 1 3

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Jerry AsherT. R

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David W

. Lazaroff

SAHARA MUSTARD Brassica tournefortii

ORIGIN: Probably native to North Africa andcentral Asia

DESCRIPTION: Sahara mustard is a perniciousweed with no natural controls in North America.Known here for less than half a century, it now dominates thousands of square miles of sandy, low elevation desert, often to the nearly completeexclusion of native annuals. It is a major threat to our famous spring wildflower displays.

BUFFELGRASSPennisetum ciliare

ORIGIN: Native to eastern Africa’s Great Rift Valley

DESCRIPTION: Buffelgrass was introduced by government and private agencies in Sonora andArizona during the last four decades as a forage cropfor lower elevation areas. It has become a scourgefrom Hermosillo, Sonora to central Arizona, reducingbiodiversity by outcompeting native plants and byfueling fierce fires that cacti and other natives are not adapted to withstand.

JOHNSON GRASSSorghum halepense

ORIGIN: North Africa

DESCRIPTION: Johnson grass was brought to theU.S. during the late 1700s by a South Carolina fami-ly; it was introduced to Arizona as cattle fodder in the1890s. It spreads quickly and is very difficult to eradi-cate, although many attempts have been made. It iscommon throughout southern Arizona at low- tomid-elevations. When under stress (frost or drought)the plant can become toxic to cattle and wildlife.

RED BROMEBromus rubens

Origin: Mediterranean region

DESCRIPTION: This weedy annual was establishedin California by 1848; it is seasonally abundant andwidespread in the Sonoran Desert region. Redbrome’s propensity to carry fires represents a real andgrowing danger to cacti and other native SonoranDesert plants, which are not fire-adapted.

TAMARISK (also called saltcedar)Tamarix ramosissima

ORIGIN: India

DESCRIPTION: This deep-rooted shrub or smalltree consumes a great amount of water, thus leavingsome areas high and dry. Its ability to out-competewillow, cottonwood, and other riparian plants has adramatic effect on wildlife as well. During the winter,for instance, tamarisk stands have only 39 percent ofthe density of birds as other vegetative communities.Only a few native animal species use tamarisk.

FOUNTAIN GRASSPennisetum setaceum

ORIGIN: Africa

DESCRIPTION: This robust perennial clumpinggrass is a common landscape ornamental in southernArizona, where it is slowly spreading into naturalhabitats, including the Tucson Mountains, especiallywashes. A few plants found in 1986 in Organ PipeCactus National Monument suggest that it may bespreading southward into Sonora, Mexico.

ARABIAN/MEDITERRANEANGRASSSchismus arabicus, S. barbatus

ORIGIN: Africa and Mediterranean region

DESCRIPTION: During years with wet winters,these closely-related winter annual grasses can beabundant across much of the northern part of theSonoran Desert, forming extensive, dense carpets.The first stems and leaves often spread out close tothe ground, effectively excluding or preventing otherannuals from sprouting.

MALTA STARTHISTLECentaurea melitensis

ORIGIN: Europe

DESCRIPTION: Malta starthistle perhaps wasintroduced to the Southwest as a contaminant in grain seed. In California it grows as a winterannual. Humans, animals, or wind can transportseeds. Dense infestations displace native plants and animals and degrade rangelands. The scale of infestation in Arizona may be relatively low atpresent, which enables an effective early response.

BULLFROGRana catesbeiana

ORIGIN: eastern United States

DESCRIPTION: This is the largest frog found inthe United States. All bullfrogs west of the RockyMountains are the result of artificial introductions.Bullfrogs were introduced into Arizona as a food ani-mal by the Game and Fish Department in 1926.These extremely prolific breeders are ravenous feeders,eating small rodents, lizards, snakes, turtles, fish,insects, and frogs, including other bullfrogs. They arequite detrimental to populations of native frogs, fish-es, and aquatic snakes.

CRAYFISHProcambarus clarki and Orconectes virilis

ORIGIN: Many species are native to the bayou country of the southern U.S.

DESCRIPTION: Crayfish have been introducedinto freshwater systems around the United States. Inthe Santa Catalina Mountains near Tucson, they arecommon in most drainages with permanent waterand can easily be observed in the biologically diverseSabino Canyon. Sonoran Desert fishes evolved without such predators that also feed on plant material and compete forthe substrates on which endangeredor threatened species lay their eggs.

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Antoinette Secade

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he desert that surrounds Tucson,Arizona, is beautiful. I wasn’t aware of that when I first arrived in the fall

of 1967. Born and raised in Kentuckyand fresh out of three years in a boardingschool, I wasn’t quite prepared for theUniversity of Arizona campus and itsimmense red brick buildings, studentpopulation almost equal to that of myhometown, and flood-irrigated landscapewith plants that I’d only seen in books. Iprobably should have read the catalog alittle more closely, because I wasn’t readyfor the mandatory ROTC either.

If you were to ask me what Tucsonwas like, all I could tell you about was thearea around campus. Not until I startedleaving the campus and Tucson itself did I see what the desert was about—anincredibly diverse landscape full of plantsand animals that were so different fromanything I had experienced. And, oh mygosh, if you climbed a small hill youcould see for miles through a forest ofironwood trees and palo verdes andsaguaros! It was so much better than thedesert of the Western movies and booksof my youth, because I was in it and itwas real! Tucson itself was a landscape fullof exotic species—palms, African sumacs,pepper trees, Italian cypress, and Alleppopines—with just a smattering of plantsnative to the desert that surrounded it. It was as if people needed to surroundthemselves with plants that were a lushreminder of where they had come from.But for me, the Sonoran Desert was beau-

tifu—so different from where I grew up,but so beautiful.

Now, so many years later, I supposeit makes sense that for a living I growplants native to the Southwest. (The “fora living” part is debatable, but I do grownative plants.) And the more I growthem, the more I come to love the unusu-al region we live in—an arid land wheremountain ranges rise up to create “skyislands.” It is a land of little rain, yet witha diverse mix of plants and animals livingtogether in incredible relationships. It’s aland of wonderful ecology, a land of won-derful stories, a hot land with cool plants.I want to tell you about just a few of theseplants that grow in the desert. They maynot be the usual plants you think of whenyou think of the desert, but they areplants with stories that grow in the glori-ous arid land that surrounds you and me.

Chuparosa, or Justicia californica,grows in the low desert. Its gray-greentwigs are bare during dry times, but witha little rain those twigs fill with leaves andred tubular flowers—lots of red flowers.On warm, rocky slopes or along arroyosyou’ll see their incredible splashes of red.And yes, chuparosa does attract humming-birds. In fact, in Spanish “chuparosa”means hummingbird and those red tubular blossoms full of nectar keep hummingbirds very busy and nourished.

Years ago I was hiking in the CoyoteMountains west of Tucson. It was lateFebruary and we’d had good winter rains.The slopes were covered in blooming

chuparosa and the ocotillo had leafed outto green canes topped with red flowers. Ihad never seen so many hummingbirds. Iwore a red cap that day and as I sat on awarm boulder, I became a part of thatlandscape as hummingbirds flew fromplant to my cap to plant.

When I’m learning about a newplant, I like to look in books to see if it

Plant Storiesof the Sonoran Desert

Peter GierlachSpadefoot Nursery

Host of “Growing Native” with Petey Mesquitey on KXCI FM community radio

Coral bean

Pete

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has any medicinal uses or if indigenouspeople used it and if they passed thoseuses along. These things make plants evenmore interesting and give them stories.

Pipe vine, or Aristolochia watsonii,has stories. The genus is derived from theGreek words meaning “best for birth, ”and another common name for it isbirthwort. Modern herbalists still declareits many uses. But what I like best is thatwithout pipe vines there would be nopipe vine swallowtails. The incredibly ill-smelling foliage of the pipe vine is the lar-val food of the pipe vine swallowtail but-terfly. Many times when I see the plant, it is covered in caterpillars.

Caterpillars remind me of anotherill-smelling desert plant called Passiflorafoetida. “This native passionflower vinewill bring gulf fritillary butterflies to youryard. It’s their larval food,” I said to anursery customer. Later that fall I askedher if she had seen the butterflies and shesaid no, she hadn’t, but she had spent thesummer picking caterpillars off the vine.

Among the warm boulders justabove the desert floor you’ll findErythrina flabelliformis, or coral bean to those afraid of that botanical name.Actually, you may not see coral bean butinstead find its bright red, hard beans onthe ground. Look around you and youmay see some naked, brittle branchespushing out of the cracks in a boulder,maybe a dried pod hanging on them.That’s coral bean. Isn’t it glorious?! If youcome to the same spot in the late spring

or early summer, the tops of those nakedbranches will have flame-red flowers andthe fan-shaped (hey, that’s what flabelli-formis means) leaves will cover thosebranches and long green pods will danglewhere once there were flowers. In the fall,the leaves of coral bean turn a beautifulyellow and drop, leaving long pods. Thepods dry and open, revealing a row ofbright red beans—coral beans. The beansare said to be poisonous, but they are sohard I can’t imagine anyone getting poi-soned without breaking some teeth.

Once a fellow who had grown up inTucson came into my nursery, and he rec-ognized that I was growing coral beans.“Oh, that’s burning bean plant,” he saidto me. “What?” I said. “When I was a little boy we’d take those hard beans and rub them on a rock ‘til they were real hot and then touch each other withthem—burning beans!” It’s glorious.

For many years I lived northwest ofTucson in what is called the IronwoodForest. It is a desert full of ironwood trees,palo verdes, mesquites, acacias, saguaros,barrel cactus, cholla, prickly pear—oh,just too many plants to list—but that area was my education. My love of thedesert grew there, and I came to feel asense of place in that desert. There was acactus there called “queen of the night”(Peniocereus greggii) or the beautifulSpanish name, la reina de la noche. It isalmost always found under a tree becausethe seed from the fruit is spread by birds.Dead-looking ribbed branches attached to

a large tuberous root stick out of theground. They are hard to find except onone night in June or early July when theybloom. Immense, funnel-shaped whiteblossoms, six inches tall and four inchesacross, suddenly appear on the dead-looking branches. An incredible fragrancepermeates the air and attracts the sphinxmoths. My wife and I would take ourdaughters into the desert to see la reina dela noche. We’d call friends and they wouldcome to see, because it is only one night.We told stories, and those nights becamestories, stories about plants and animals,not just old stories, but new stories. Our stories remind us over and over about the beauty of the Sonoran Desert.

Years ago I was hiking in the

Coyote Mountains west of

Tucson. It was late February and

we’d had good winter rains.The

slopes were covered in bloom-

ing chuparosa and the ocotillo

had leafed out to green canes

topped with red flowers. I had

never seen so many humming-

birds. I wore a red cap that day

and as I sat on a warm boulder,

I became a part of that land-

scape as hummingbirds flew

from plant to my cap to plant.

T

Pete

r G

ierla

ch

Peter Gierlach

Coral bean

18

side-blotched lizard three inches long challenged my walk in the desert. His

blue shoulder markings flashed ashe did his push-ups to impress me with hisvigor and to defend his territory. I posedno threat to him, but a more serious andsilent intruder was on its way. Buffelgrasswas invading Organ Pipe Cactus NationalMonument.

Buffelgrass was brought to Tucsonfrom Africa, the Middle East, and India in 1939. Scientists with the U.S.Department of Agriculture, PlantMaterials Center in Tucson experimentedwith buffelgrass for decades. They hopedthis rapidly growing, drought-tolerantgrass would provide abundant livestockforage and stop soil erosion. Buffelgrassinevitably escaped from the experimentalplots and began spreading exponentially.Only 45 years or so after its arrival inTucson, buffelgrass was found more than100 miles away at Organ Pipe CactusNational Monument. In the mid-1980s,Dr. Richard Felger described the species as being “uncommon, perhaps rare” but increasing at Organ Pipe. Over thenext 10 years, buffelgrass populations rapidly expanded and the species becameestablished on more than 20 square milesof wilderness.

Buffelgrass aggressively colonizes andrapidly alters Sonoran Desert communi-ties. Mature plants can be as tall as threefeet, larger than most native grasses.Buffelgrass competes with native plantspecies for water, nutrients, and space.Seedlings of many native plants can notsurvive under the thick layer of buffelgrass.Neither can many lizards, which dependon sunny areas when they need to raisetheir body temperatures. Rodent popula-tions shift from species that prefer opendesert habitats to species more typical ofgrasslands. Gambel’s quail and otherground-feeding birds have difficulty mov-ing through the dense grass and lose theiraccess to a nutritious mix of seeds, greens,and the invertebrates important to hatch-ling diets. It’s no surprise that nectar-feeding birds and insects also lose theirfood sources when wind-pollinated grassestake over. Monotonous grass fields replacewinter and summer wildflower shows.

Of all the effects African grasses havehad on the Sonoran Desert, fire is themost serious. Fire did not naturally occurin the desert because plants are too farapart for fire to spread. Grasses and othernon-native plants provide the fuel thatconnects the sparse native plants. Since the arrival of non-native grasses, fires inthe desert have increased in frequency and magnitude. Most native desert plantsdie when burned and do not re-establishquickly in burned areas. Burned buffel-grass can push up new stalks within days after a fire and new seedlings sprout

Battling Buffelgrass:You Can’t Win If You Don’t Play

Sue RutmanOrgan Pipe Cactus National Monument

Volunteer Tom Wilder holding a largebuffelgrass plant that is several years old.Plants this size can produce thousandsof seeds per year.

readily on the barren ground. Burnedareas become fields of buffelgrass that aredifficult to eradicate.

The arrival of buffelgrass on OrganPipe evoked visions of a dismal future. Ifuncontested, the ecological effects of thisspecies would be severe, widespread, andperhaps permanent. The National ParkService would fail at its most fundamen-tal mission: to preserve and protect thearea for future generations. Would wesoon be presiding over an African savan-na? The risk of doing nothing was toogreat, but how were we to respond?

Experts were doubtful or pessimisticabout controlling buffelgrass. No one hadtried eradicating the species on a largescale. Academic ecologists advised againstmechanical control (digging up plants)because the disturbance of digging wouldlikely favor the species, not eradicate it.But herbicides didn’t kill the plants and

neither did burning. Given no otheroptions, we started experimenting withmechanical control.

We started work on a convenientlylocated test area in November 1994.Sixteen employees and volunteersremoved buffelgrass from along ArizonaState Route 85 near the visitor center atOrgan Pipe. In two hours we removedmore than 50 large trash bags of buffel-grass from about 0.1 mile of roadside.The bags were taken to the municipaldump and were buried.

The results gave us reason to beoptimistic. One year after the test project,we spent one day removing seedlings.Two years after the test project and there-after, we removed one to three seedlingsper year.

Buoyed by the success of the testproject, we moved on to a large infesta-tion covering several square miles west of Quitobaquito Springs along theU.S./Mexico International Boundary.During the spring of 1996, a group ofstudents from Earlham College, Illinois,spent two days in the area and removedseveral tons of buffelgrass. We were sur-prised to see very little reestablishment,even now after several years.

These small and encouraging effortsimplied that mechanical removal couldbe successful if eradication sites were visited for at least two years. During thesecond year, seedlings could be removedbefore they produced seeds. With noinput of seeds the buffelgrass population

could not reestablish or expand. Withcontinual, but low-effort maintenance,buffelgrass control seemed possible andeffective.

The buffelgrass control program atOrgan Pipe shifted into high gear duringthe winter of 1997-1998. That winter,two volunteers and employees spent atotal of 890 hours removing buffelgrass.By the spring of 1998, nearly the entireMonument, with the exception of theextreme southwestern corner, had beencleared of buffelgrass. During the winterof 1998-1999 volunteers and employeesspent about 1,000 hours removing buffel-grass from the southwest corner and Dos

The arrival of buffelgrass on

Organ Pipe evoked visions of a

dismal future. If uncontested,

the ecological effects of this

species would be severe,

widespread, and perhaps

permanent.

In this monotonous buffelgrass field in Sonora,Mexico, the needs of one species—cattle—has leftfew resources for native plants and animals.

19

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Because of frequent and severe buffelgrass fires (left),many wooden fence posts in Sonora have been replacedby concrete ones (right).

T. R. V

anDevender (all)

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nprecedented and unnatural wildfires are destroying native plant communities of the

Sonoran Desert. Within the last seven years destructive wildfires haveconsumed large tracts of some of themost scenic and species-rich parts of the desert.

Red brome, an annual grassnative to the Mediterranean region,arrived in southern Arizona around1900. It grows in dense stands of close-ly spaced, erect stems, providing abun-dant fuel between the widely-spacednative plants. Red brome grows backmore vigorously after fire, and withmore red brome, there’s more fire—anaccelerating self-perpetuating fire cycle.

Even though some native plants resprout, populations of mostperennial plants are catastrophicallyreduced or eliminated, especially afterrepeated fires. Many mature saguarosand most young saguaros are oftenkilled with a single fire. Smaller cactisuch as pincushions, hedgehogs, prickly pear, and all species of chollaare usually killed, as well as palo verde trees. While the damage fromred brome (and to a lesser degree other non-native grasses) is alreadyextensive and landscapes permanentlyaltered, we have only begun to see the scope of the degradation that is set to occur on a grand scale.

Red Brome and WildfiresJerry Asher

USDI Bureau of Land ManagementOregon State Office

The top photograph was taken 22 miles north of Oracle, Arizona,prior to a May 1995 fire involving red brome. The middle photo

shows the aftermath of the fire and its devastating effects on native vegetation. The bottom photo was taken less than one

year after the fire. Note the increased abundance of red brome.

Red brome

20

Lomitas area (the southeast boundary),and surveying areas in the west-centraland northwestern part of the Monument.Small (room-sized) outlying populationswere found and eradicated. By the springof 1999, we estimated that 100 tons

of buffelgrass had been removed from Organ Pipe.

The buffelgrass control program onOrgan Pipe Cactus National Monumenthas been a success so far. Time and moni-toring will determine how long the suc-cess story will last. Of particular interestwill be the response of buffelgrass to theabove-average rainfall of the summer of 1999.

Given the vast populations of buffelgrass in neighboring Sonora,Mexico, their seeds will surely hitch ridesinto the Monument with truck tires anddust devils. It is unlikely that Organ Pipewill ever be able to totally escape thispotentially devastating species. But if weremain vigilant against new occurrencesand root them out when we find them,our goal of minimizing buffelgrass infestations seems attainable—at least for now. We owe as much to that side-blotched lizard!

It is unlikely that Organ Pipe will

ever be able to totally escape

this potentially devastating

species. But if we remain vigilant

against new occurrences and

root them out when we find

them, our goal of minimizing

buffelgrass infestations seems

attainable—at least for now.

Constant vigilance will be necessary to protect and preserve this beautiful desert landscape frombuffelgrass and other invasive species.

Steve Phillips Buffelgrass

U

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the general public about the preservationof biological diversity through invasivespecies control with hands-on trainingand outreach classes. In less than twoyears, over 500 Weedwacker volunteershave removed fountain grass and buffelgrass from more than 5,000 acres of Tucson Mountain parklands.

We generated comprehensive, defini-tive lists of non-native plants and animalsin the Sonoran Desert including the florasof the Tucson Mountains and Ragged Top.Currently, ASDM scientists, in coopera-tion with BLM, are compiling a biologicalinventory at the Ironwood NationalMonument. The Desert Museum plans to create other educational materials oninvasives, among them a guide to threaten-ing non-natives on islands in the Gulf ofCalifornia. We contributed to a manage-ment plan for these islands that emphasizesnon-native species control.

We initiated a program in whichmembers of the Seri Indian communityare trained in methods to control non-native weeds and rats, integrating modernbiological techniques and ideas with

traditional knowledge. The trainees areuniquely qualified to fill research andconservation posts on the islands andcoast of the Gulf of California, a benefitto their economy as well as to their environment. When possible, we will par-ticipate in other international efforts tocoordinate invasive species control efforts.

The Museum will continue to makeinformation on invasive plants and otherspecies more accessible to the publicthrough educational programs, publica-tions, and expansion of our website(www.desertmuseum.org.)

With other agenciesThe Desert Museum is committed

to cooperating with other agencies andorganizations, and with people in desertcommunities, in their efforts to keep theunique habitats of the Sonoran Desertfrom being further invaded by non-native plants and animals. We hope that by working together, we can succeed in bringing this biological “wildfire” under control.

Para-ecologist courses are training Seri Indians in methods for controlling non-native plantsand animals.

ASDM efforts

f you think that controlling weeds inyour yard or garden is a challenge, consider the immensity of controlling

the over 220 non-native plants in theSonoran Desert region. These plants havehitched rides here by nestling in socks,sticking to dogs, hiding between thetreads of tires, or traveling in humanhands. If you add to this number over 40 fishes, 7 mammals, 7 birds, 130 inver-tebrates, and 13 reptiles and amphibiansthat have all hopped, swum, flown,crawled, or been transported to theSonoran Desert region you have a num-ber of exotic species estimated to be about400. This overwhelming menagerie ofcreatures that have invaded an area morethan ten times the size of Connecticutcan only be addressed by cooperationbetween the agencies and countries thatspan this region. The Arizona-SonoraDesert Museum is one of the many pri-vate organizations and public agenciesthat are working together to identifywhich plants and animals may cause ecological and economic problems.Collectively, we hope to implement themost effective, most efficient and leastdisruptive ways to deal with these species.

The Arizona-Sonora DesertMuseum has facilitated the cooperationneeded to address these biological inva-sions. In May of 1998 the symposium“Invasive Species in Sonoran DesertEcosystems” brought together researchers,government officials, and concerned citi-zens to address the problems of non-

native biological invasions in the SonoranDesert region. Further cooperative effortsare an ongoing result of the symposium.Since that seminal gathering of interestedpeople our staff has initiated and partici-pated in related projects on the museumgrounds and in the greater SonoranDesert region. The projects mentionedbelow reflect a multi-pronged approach,including prevention, education, research,monitoring, control, and eradication ofnon-native species.

On the groundsOn Museum grounds we continual-

ly remove invasive non-native plants, primarily pulling them by hand or usingother mechanical means. We featurenative plants on the grounds in an effortto promote their use in home landscapes.We are also monitoring spiny-tailed iguanas that were introduced to theMuseum grounds 20 years ago to evaluate their potential invasiveness.

In January, 2000, the DesertMuseum created a special task forcewhich became the Tucson MountainWeedwackers (TMWW.) This group is dedicated to the eradication of invasivenon-native plants in the Tucson Moun-tains. This collaborative organizationincludes the Arizona-Sonora DesertMuseum, Pima County’s TucsonMountain Park, Saguaro National Park, The Sonoran Arthropod StudiesInstitute, and hundreds of communityvolunteers. The TMWW group educates

Pulling Together:The Desert Museum Battles a Biological Wildfire

Patty Westf ormer Research Coordinator

Arizona-Sonora Desert Museum

Barb SkyeCurator of Botany

Arizona-Sonora Desert Museum

Ant

oine

tte

Sega

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Jeanne Broom

e

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Karen K

rebbsJeanne B

roome

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(1998), Organ Pipe Cactus NationalMonument (1999), and others; ecologi-cal analyses, resource guides, and publicoutreach materials; and the efforts ofnumerous dedicated individuals all havecontributed to a new focus and sense of urgency.

The threat posed by invasive plantsto Sonoran Desert biodiversity needs acomprehensive response. In the remainderof this article, we discuss the nature of theArizona response, primarily in regard tothe Sonoran Desert. Response strategieslargely fall into the following categories:partnerships, public policy, technologicaltools, and education and outreach.

Partnerships: crossing boundariesInvasive plants do not respect

boundaries; they move with equal disre-gard across international, state, andlandownership lines. They impact privateand public lands, rural and urban areas,ranches, farms, and wildlands alike. Toprevent their movements and controltheir impacts, we must respond in kind.Partnerships that cross boundaries—not

only of ownership, but also of values,interests, and capabilities—will be a prerequisite for success. My neighbor’sproblem is my problem; together we cansolve it. In addition to landowners andmanagers, we also must include landusers, whose actions may spread repro-ductive parts of plants or otherwise createconditions favorable to colonization byinvasive plants. Partnerships play a keyrole in leveraging and effectively using thescarce resources—funds, tools, personnel,and knowledge—that are available tomanage invasive plants.

In contrast to many of its sister statesin the West, Arizona currently lacks astate-imposed organizational and fundinginfrastructure that dictates how at leastnoxious weeds are managed. In the lastfew years, however, more than ten volun-teer and local organizations have been created within Arizona that cooperativelymanage invasive species. Known generallyas Cooperative Weed Management Areas(CWMA), these grass-roots organizationsinclude any combination of representationfrom: county, state, and federal govern-ment; private landowners; academic andother technical assistance institutions; non-governmental organizations; tribes; andnatural resource conservation and irriga-tion districts. They are organized either ona geographic basis, with cooperators gener-ally sharing a common suite of invasiveplants, or in some cases are designed toaddress a particular problematic species nomatter where it occurs. Still other groups,

such as Tucson Mountain Weedwackers,are informally organized and may focus ona limited geographic area or set of part-ners. As volunteer organizations, CWMAsin Arizona face the common challenges ofsecuring enough people and funding toaccomplish their work.

To complement on-the-groundactions of CWMAs and to provide themassistance toward achieving their goals,other types of coordinating bodies havebeen established or are contemplated.These groups, such as the SouthwestVegetation Management Association andPima Invasive Species Council, whichaddress invasive plant issues in Arizona andPima County, respectively, can act as advo-cacy bodies for public policy reform andresearch needs, sources of technical andeducational information, and clearing-houses for identifying grant opportunities.

Public policy reformWithout effective public policy,

management strategies for invasive speciesare difficult to implement and sustain.One of the purposes of this issue ofsonorensis is to increase the awareness of policy makers. Because the SonoranDesert extends into portions of BajaCalifornia and Sonora, Mexico, policyreform and coordination must encompassinternational as well as state and nationalissues. Recently, a number of individualsand organizations within the SonoranDesert Ecoregion petitioned the ArizonaDepartment of Agriculture to add four

ince the initial publication of the“Bioinvaders” issue of sonorensis in

the winter of 1999, much has happened in the arena of invasive speciesmanagement. During the past few years, a critical increase in awareness hasoccurred regarding the seriousness of the problem at the national, state, andlocal levels. In this article we provide anoverview of the most important recentadvances in the management of invasiveplants, with a focus on activities withinthe Sonoran Desert Ecoregion.

A national call to actionIn February 1999 President Clinton

issued an Executive Order on invasivespecies. This action continues to bringnational attention to the threat invasive

species pose to our nation’s economy andnatural heritage. The order established theNational Invasive Species Council, whosetasks are to provide national leadership oninvasive species and to ensure that federalagency activities concerning such speciesare coordinated, complementary, cost-efficient, and effective. The councilincludes several federal departments and agencies and is co-chaired by theSecretaries of the Interior, Agriculture,and Commerce. The order required thepreparation of the National InvasiveSpecies Management Plan, whose firstedition was completed in January 2001.The plan provides a blueprint for federalaction in coordination with other govern-mental entities and stakeholders to pre-vent the introduction of invasive species,provide for their control, and minimizetheir impacts. The order also established astakeholder Invasive Species AdvisoryCommittee to assist in the implementa-tion of the national management plan.The Nature Conservancy is one suchstakeholder organization that is a memberof the advisory committee.

Parallel to the above efforts, otherimportant initiatives are underway at thenational level that relate to the manage-ment of invasive plants. Consistency inthe collection of data that documents theoccurrence of invasive plants is crucial for accurately tracking their spread andassessing their impacts. Recently, theNorth American Weed ManagementAssociation, a membership-based national

organization, worked with federal agencytechnical staff to develop standards formapping the occurrence of invasiveplants. These standards already have beenadopted by a number of federal landmanagement agencies, as well as by otherorganizations in the United States andCanada. The association currently isdeveloping standards for weed-free hay, of particular importance to western states,and for monitoring the use of biocontrolagents. A primary need is adequate fund-ing for on-the-ground control activitiesby locally organized groups. Congress hastaken up legislation that would providefederal matching dollars through thestates to support such activities. Althougha bill has yet to pass, the increased aware-ness within Congress that adequate fund-ing is needed is a positive step forward.

Arizona respondsUntil the late 1990s the focus of

invasive plant management activities inArizona had been on federal- and state-regulated noxious weeds—generallyspecies that have an impact on agricul-ture—and mostly concentrated withinthe northern part of the state. Severalrecent events not only have highlightedconcerns about invasive plants within thesemi-desert grassland and desert areas ofthe southern part of the state, but alsohave turned attention to their impact onArizona’s wildlands. Symposiums andworkshops hosted by organizations suchas the Arizona-Sonora Desert Museum

Invasive Plant Management in the Sonoran Desert: An Update

Nina ChambersProject Manager, Sonoran Desert Ecoregion

Sonoran Institute

John A. HallSonoran Desert Program Manager

The Nature Conservancy

Barb SkyeCurator of Botany

Arizona-Sonora Desert Museum

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S

Bob Perrill

Kas

ey A

nder

son

Partnerships that cross

boundaries—not only of

ownership, but also of values,

interests, and capabilities—will

be a prerequisite for success.

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In the mid-1980s we comparedplants, birds, small mammals, andgrasshoppers living in stands of nativegrasses with those in adjacent areas covered with exotic grasses. Our studiestook place at the 8000-acre Appleton-Whittell Research Ranch Sanctuary of theNational Audubon Society in the foothillsof the Huachuca Mountains.

Plants were much less diverse in theexotic grass stands. Not only were thenative grasses rare in the exotic stands,but native wildflowers and shrubs weremissing or scarce as well. Only mesquitetrees did equally well in both. Since exotic lovegrasses form very dense patches, it is not surprising that mostnative plants were unable to grow among them.

With one exception, the summer resident birds preferred native grassland.(If you want to see such species as EasternMeadowlarks and Cassin’s Sparrows in the summer, visit native, not exotic, grass-lands.) The exception is Botteri’s Sparrow,which appears to prefer the exotic Boerlovegrass stands instead of areas coveredwith native grasses. These sparrows alsofavor bottomlands covered with sacatongrass (Sporobolus wrightii), a native flood-

plain species that also occurs in dense, tall, somewhat uniform stands. Birds present in the winter have the same preferences as the summer residents.

We found a similar pattern in therodents. Most rodents, including theinsectivorous pygmy mouse (Baiomys taylori), preferred native grassland. Theonly rodent that favored exotic stands wasthe native Arizona cotton rat (Sigmodonarizonae). Like the Botteri’s Sparrow, this animal is also common in sacatonbottomlands. Twice as many kinds ofgrasshoppers, important in the food chainof our grasslands, were common in nativethan were common in exotic stands.Ironically cattle, too, prefer the nativegrasses, turning to the African grasses only when nothing else is available.

Areas with diverse native species are more interesting and aestheticallypleasing than are uniform stands ofAfrican grasses. But more importantly,diverse native communities are a naturalgene bank—one that has passed throughan evolutionary sieve that allows them to survive under our extreme conditions.The lesson is clear: Learn from the past.Foster diversity in both plants and animals by planting natives.

26

wildland invasive species to the list ofstate-regulated species. Management of one of these species, buffelgrass(Pennisetum ciliare), also has been pro-posed as a case study that could serve toimprove coordination of federal policyon invasive species. On the horizon isthe development of an Arizona invasivespecies management strategy that couldprovide the impetus and blueprint for the state’s plan of action to support andfund invasive species management across the state.

Using technologyThe effectiveness of CWMAs can

be improved through the strategicdevelopment and consistent applicationof technical support tools. Such toolsshould not only lead to better coordi-nation among CWMA participants,but also link CWMA data collectionand analysis results with regional andnational efforts. The Southwest ExoticPlant Mapping Program (SWEMP),managed by the U.S. GeologicalSurvey’s Colorado Plateau Field Stationin Flagstaff, is an example of a collabo-rative effort to develop regional infor-mation on the distribution and abun-dance of invasive plants. By applyingcommon core standards of data collec-tion and using compatible databasesoftware, CWMA participants canfacilitate information exchange andbetter plan response strategies withtheir cooperators. In addition, they

can make their data useful at largergeographic scales of analysis. Regionaland national analyses of species occurrence data may permit forecast-ing the potential spread of invasivespecies and lead to more effective preventive measures. Other criticaltechnical needs include: species-specific research on basic biology,impacts to biodiversity, and controlmethods; tools for priority-setting; and simulation models that can betterpredict potential spread and impacts of invasive species.

Getting the message outAlthough progress has been made

toward management of invasive plantsin the Sonoran Desert specifically andArizona in general, much work remains,and a continued commitment to actionis needed. Education and outreach—vital tools for raising awareness amongpolicy makers and the public in gener-al—will take on greater importance inthe years ahead. The messages that con-vey the impacts of invasive plants arethere for those who are willing to readthem: impoverished grazing lands,degraded wildlife habitat, potential forfire within ecosystems that did notevolve with fire, reduced crop yields,devalued real estate, and loss of biodiversity. These messages need to reach all who can make a difference, and we all need to be messengers.

Exotic Grasses &Native Wildlife

Jane H. Bock and Carl E. BockDepartment of Biology

University of Colorado, Boulder

A cotton rat is the only common rodent in exotic grasslands at the Research Ranch.

The Botteri’s sparrow (foreground) is one of the few animals more common in exoticgrasslands, whereas the closely-relatedCassin’s sparrow (background) is one of a variety of birds that are much more common in native grasslands.

Plains lovegrass

Car

l Boc

k

Carl B

ock (both)

Stands of Boer lovegrass, such as this one at the Research Ranch, support a much reducedvariety of native plants and animals, compared to native grasslands.

xotic lovegrasses, purposely intro-duced in the 1940s, have spread

through southeastern Arizona,crowding out native plants in some of thestate’s most productive grasslands. Casualobservations made us suspect that thediversity of living things might be reducedin the areas dominated by these exotics.

At the end of the nineteenth centuryovergrazing by domestic livestock coupledwith a prolonged drought denuded largeareas and greatly reduced plant cover inothers. In an effort to restore the range for cattle, the Soil Conservation Serviceplanted two species of African grasses—Lehmann’s lovegrass, E. lehmanniana,and Boer lovegrass, E. curvula. The grass-lands were formerly a mixture of nativegrasses, including plains lovegrass (E.intermedia), and other plants. NowAfrican lovegrasses almost totally dominate parts of some mesas.

E

What Can You Do?

Native plants are beautiful! They can bring year round color and texture into your yard and your community (left and above). Deserthikers and campers should be careful to clean their gear and clothingbefore returning home (top right).

At Home○ Begin with your own yard. Landscape with

native species or non-invasive plants appro-priate for your area, and keep your propertyfree of invasive weeds.

○ When you plant exotics in your yard watchcarefully for signs of aggressive spread; takeappropriate action if it is observed.

○ Neuter your pet cats and dogs or keep themconfined. Don’t release pets into the desert, or aquarium plants and fish into desert waterways.

○ Avoid disturbing natural areas—disturbedground favors invasive exotics.

○ Be careful not to send or receive potentiallyharmful plants or animals through the mail.Know what you’re sending and receiving!

In the Community○ Adopt a local roadside, trail, park area, or

riparian area. Develop a program for detect-ing, reporting, and possibly controlling weedinfestations. Work with community leaders orland managers in developing such a program.

○ Document the location of noxious weeds inyour community through the use of maps,photos, and survey forms. Share the informa-tion with community planners and landmanagers.

○ Native plants are beautiful! Prove it to yourcommunity by starting a native plantsdemonstration garden.

○ Go public. Conduct a public awareness campaign to educate local citizens about steps they can take to stem the spread of exotic plants and animals.

○ Work with county extension agents and local land management agencies to put up informational signs where weed infestations occur.

○ Tell your friends and relatives about this problem.

When You Travel○ Clean all camping gear, clothing, and shoes

before leaving an area to avoid inadvertentlytaking seeds along to the next campsite,county, or state.

○ Don’t camp in or hike through weed infestedareas. Stay on designated trails.

○ Refrain from picking wildflowers or diggingup plants.

○ Don’t bring plants, fruits, soil, or animalsinto the country from abroad illegally orwithout having them inspected by quaran-tine officials; fill out agricultural declarationforms completely and honestly.

○ Completely wash down boats and boatingequipment and blow out personal watercraftintakes before transporting them from one water body to another. Don’t dump bait in the water!

Al Morgan

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Rico Leffanta

29T. R

. VanD

evender

The Sonoran Institute, founded in 1990, is a nonprofit organization that works withcommunities to conserve and restore important natural landscapes in western NorthAmerica, including the wildlife and cultural values of these lands. The Sonoran Institute’scommunity stewardship work creates lasting benefits, including healthy landscapes andvibrant, livable communities that embrace conservation as an integral element of theireconomies and quality of life.

7650 E. Broadway Blvd., 203 • Tucson, AZ 85710520.290.0828 • www.sonoran.org

1510 E. Ft. Lowell Road • Tucson, AZ 85719520.622.3861 • nature.org/arizona

The Arizona-Sonora Desert Museum is a private nonprofit educational institutionwhose mission is to inspire people to live in harmony with the natural world by fosteringlove, appreciation and understanding of the Sonoran Desert. Founded in 1952, it is recognized worldwide as a leader in natural history interpretation and exhibitry. Throughits combination of zoological, botanical, geological and natural history presentations,ASDM stresses the vital interrelationships of the land, water, plants, wildlife and people of the Sonoran Desert region.

2021 N. Kinney Road • Tucson, AZ 85743-8918520.883.1380 • www.desertmuseum.org

The Nature Conservancy, founded in 1951, is a global nonprofit conservation organization. Its mission is to preserve the plants, animals, and natural communities thatrepresent the diversity of life on Earth by protecting the lands and waters they need to survive.

Jim M

alusa

Mark D

imm

itt

Jeanne S. Broom

eR

ick Daley

Rick D

aley

The earth is not wanton to give up her best to every comer, but keeps a sweet,

separate intimacy for each.Mary Austin