Arizona’s wildlife history is an example of a timeline that occurred in many developing landscapes: an era of exploitation and eradication (1800s–1950s) followed by an era of restoration and management (1980s–present).
However,
there are some factors that were unique to the United States that led to
distinct trends in wildlife populations when compared to those same species
across the border in Mexico.
The
following summary of research (Part 1) lists 16 Arizona species that were
extirpated or greatly reduced and whether they have recovered. Part 2 looks at 10 species that occur in both
Arizona and Mexico and why their populations followed different trends.
This
research illuminates the current state of wildlife and ecosystems in Arizona
and helps explain the factors that got us here.
Part 1: Arizona vs. Wildlife
The
following summary organizes species into groups based on their population
trajectories: the “Great Returns” that were extirpated but have been
successfully reintroduced, the “Survivors” that have been greatly reduced but
still persist, and the “Lost Causes” that were extirpated but have not been
successfully reintroduced.
I. The "Great Returns": Extirpated & Successfully
Reintroduced
These
species were completely removed from the state but have been restored, often
using proxy subspecies or captive breeding.
Rocky Mtn Elk
Extirpation
Date/Cause: 1900: The native Merriam’s subspecies was hunted to extinction for
meat and teeth.
Reintroduction
Date/Area: 1913–1928: Rocky Mtn elk from Yellowstone were released near
Winslow, Alpine, & Kingman.
Key Trend/Notes:
Ecological Substitution: A proxy subspecies filled the empty niche, expanding
rapidly due to lack of competition.
Mexican Gray Wolf
Extirpation
Date/Cause: 1970: Eradicated by federal predator control programs
(poison/traps) to protect livestock.
Reintroduction
Date/Area: 1998: Captive-bred wolves released in the Blue Range Primitive Area.
Key Trend/Notes:
Predator Tolerance: Success is biologically high but socially controversial;
relies on ongoing conflict management.
California Condor
Extirpation
Date/Cause: 1924: Vanished due to lead poisoning (bullets in carrion) and
shooting.
Reintroduction
Date/Area: 1996: Released at Vermilion Cliffs.
Key Trend/Notes:
Intensive Care: Survival relies on active management (chelation therapy for
lead) rather than self-sufficiency.
River Otter
Extirpation
Date/Cause: 1950s: The native Sonora subspecies was trapped out for fur.
Reintroduction
Date/Area: 1981–1983: Louisiana
subspecies released in the Verde River.
Key Trend/Notes:
Another Proxy: Like the elk, a non-native subspecies was used to successfully
fill the vacant ecological role.
Black-footed Ferret
Extirpation
Date/Cause: 1960s: Poisoning of their food source (prairie dogs) led to total
extirpation.
Reintroduction
Date/Area: 1996: Reintroduced in Aubrey Valley (Seligman).
Key Trend/Notes:
Disease Barrier: Success is limited by sylvatic plague; requires dusting
burrows and vaccines to persist.
Apache Trout
Extirpation
Date/Cause: Mid-1900s: Hybridization with non-native rainbow trout and habitat
loss.
Reintroduction
Date/Area: 1955–Present: White Mtns (managed by White Mountain Apache Tribe
& AZGFD).
Key Trend/Notes:
The First Win: Became the first sportfish in history to be delisted from the
Endangered Species Act (2024).
II.
The "Survivors": Reduced but Persisted
These species were decimated by unregulated market hunting or
predator control but survived in rugged refugia (escape terrain).
Desert Bighorn
Historic Low
Point: Early 1900s: Reduced by diseases from domestic sheep and market hunting.
Survival Factor:
Terrain: Survived in the most inaccessible desert peaks (Grand Canyon, Kofa).
Current Status:
Translocated: Populations are moved to historic ranges (e.g., Santa Catalinas,
Virgin River) to ensure genetic diversity.
Mountain Lion
Historic Low
Point: 1960s: Bountied as "vermin" until 1970.
Survival Factor:
Elusiveness: Solitary nature and rough terrain made total eradication
impossible.
Current Status:
Stable: Managed as a big game species; populations are robust statewide.
Beaver
Historic Low
Point: 1890s: Trapped out of major rivers (San Pedro, Santa Cruz).
Survival Factor:
Cryptic Behavior: Survived in deep canyons (Verde/Black River) by using bank
burrows instead of lodges.
Current Status:
Recovering: Reintroduced to the San Pedro (1999); used today for watershed
restoration.
Pronghorn
Historic Low
Point: 1920s: Fences cut off migration; market hunting reduced herds.
Survival Factor:
Open Space: Remnant herds survived in vast private ranchlands (Babbitt
Ranches).
Current Status:
Managed: Sensitive to habitat fragmentation; relies on modifying fences for
movement.
Gunnison’s Prairie Dog
Historic Low
Point: 1930s: Poisoned across vast areas.
Survival Factor:
Remote Refugia: Survived in the high-elevation Aubrey Valley; resistant to
plague.
Current Status:
Keystone: Their persistence allowed the Black-footed Ferret reintroduction to
happen.
III. The "Lost Causes": Extirpated & Failed (or Struggling)
Reintroductions
Complex social behaviors or specific habitat needs made
simple reintroduction impossible.
Thick-billed Parrot
Extirpation
Cause: 1938: Shooting/Poaching.
Reintroduction
Outcome: Failed (1986–93): Chiricahua Mtns.
Why It Failed:
Cultural Knowledge: Captive birds lacked flock wisdom to avoid hawks and find
food.
Masked Bobwhite Quail
Extirpation
Cause: 1900: Cattle overgrazing destroyed tallgrass cover.
Reintroduction
Outcome: Struggling (1937–Present): Buenos Aires NWR.
Why It Failed:
Habitat Specificity: Reintroduced birds often die due to lack of specific cover
and predation; almost entirely reliant on captive releases.
Gila Topminnow
Extirpation
Cause: 1940s: Invasive Mosquitofish.
Reintroduction
Outcome: Mixed/Struggling: Multiple failures in the 80s/90s.
Why It Failed:
Invasive Barrier: Cannot survive where aggressive non-native fish are present.
Jaguar
Extirpation
Cause: 1963: Killed as predator.
Reintroduction
Outcome: Natural Transients Only: No formal reintroduction.
Why It Failed:
Political/Social: Only solitary males currently cross from Mexico; no breeding
population exists.
Grizzly Bear
Extirpation
Cause: 1936: Killed as predator.
Reintroduction
Outcome: Permanently Extirpated.
Why It Failed:
Social Tolerance: Requires vast, roadless wilderness that no longer exists in
AZ; no plans to reintroduce.
Unifying Trends in Arizona Wildlife History:
The Predator Paradox:
Predators (wolves, grizzly bears and black bears, jaguars,
lions) were targeted by federal policy for eradication to protect livestock. Only the cryptic/solitary ones (lions, bears
in rough terrain) survived. Reintroducing social predators (wolves) has been
biologically successful but socially difficult.
The Proxy Solution:
When a native subspecies was completely lost (Merriam's Elk,
Sonora Otter), biologists successfully substituted a close relative (Rocky Mtn
Elk, Louisiana Otter). These ecological
substitutes often thrived because the niche was wide open and they were
generalists.
The Behavioral Barrier:
Reintroductions of intelligent, social animals (Thick-billed
Parrot) or habitat specialists (Masked Bobwhite) often fail. Hard releases (letting animals go) work for
generalists like elk but fail for species that require learned behavior or
specific micro-habitats.
Part 2: Arizona vs. Mexico
This analysis breaks down Arizona’s extirpated and reduced
species by comparing them to their source populations in other U.S. states and
their often-distinct fates across the border in Mexico.
The overarching trend reveals a paradox: while the U.S.
effectively managed game species (elk, sheep) through public land regulation,
Mexico’s private land system (ranchos) inadvertently served as the final
lifeboat for nongame species (wolves, prairie dogs, parrots) that were
systematically eradicated in the U.S.
Successful Reintroductions: The Game Bias
The species that succeeded in Arizona were often abundant
elsewhere in the U.S. but had been wiped out or severely reduced in Mexico.
Rocky Mtn. Elk
Status in Other
U.S. States: Thriving: Millions exist across the Rockies (CO, MT, ID).
Status in
Mexico: Extirpated / Rare: Native Merriam’s were also lost in Mexico. Small,
private herds of Rocky Mtn. elk exist now on high-fence ranches in
Coahuila/Sonora.
Accounting for
the Difference: Public Land Management: The U.S. model of public land hunting
funded the massive translocation efforts. Mexico lacked the public land base or
agency funding to replicate this scale of reintroduction.
River Otter
Status in Other
U.S. States: Secure: Abundant in the Mississippi Delta and Pacific Northwest.
Status in
Mexico: Critical / Extirpated: The native Sonora otter is likely extinct in the
Colorado River Delta due to the complete drying of the river before it reaches
the sea.
Accounting for
the Difference: Water Policy: Arizona’s otters survive in protected flows
(Verde/Salt). In Mexico, the water is siphoned off for agriculture before it
can support otter habitat.
Mexican Gray Wolf
Status in Other
U.S. States: Extirpated: Historically ranged into NM/TX (now reintroduced
there).
Status in
Mexico: Reintroduced (Struggling): Mexico began releasing wolves in the Sierra
Madre in 2011. The population is smaller and more fragile than the AZ/NM
population.
Accounting for
the Difference: Prey Base: In Arizona, wolves rely on abundant elk. In Mexico,
elk are absent and deer are scarcer, forcing wolves to target livestock,
leading to immediate conflict with ranchers.
Reduced/Survivors: The Refugia Divide
Species that held on in Arizona often did so in rugged
terrain, while in Mexico, their fate depended heavily on the stewardship of
individual landowners.
Desert Bighorn
Status in Other
U.S. States: Stable: NV, CA, and UT have strong, managed herds.
Status in
Mexico: Stable / Commercialized: In Sonora and Baja, bighorn are a high-value
commodity. Private ranchers protect them aggressively to sell high dollar
hunting tags ($50k+).
Accounting for
the Difference: Economic Incentive: In the U.S., bighorn are protected by state
agencies as a public trust. In Mexico, they survived because they became a
private asset worth protecting from poachers.
Pronghorn
Status in Other
U.S. States: Secure: WY and MT have massive herds.
Status in
Mexico: Endangered (Sonoran Subspecies): The Sonoran Pronghorn (El Pinacate) is
critically endangered.
Accounting for
the Difference: Barriers: The U.S. herds had open range. The Mexican herds were
hemmed in by highways (Hwy 2) and border fencing, severing their ability to
find water during droughts.
Beaver
Status in Other
U.S. States: Abundant: r egained range
across the West.
Status in
Mexico: Recovering (Delta): The Colorado River Delta saw a miraculous,
short-term return of beavers following the "Pulse Flow" (Minute 319)
water release in 2014.
Accounting for
the Difference: Resilience: Beavers in Mexico proved they are waiting in the
wings; they only lack the water, whereas U.S. populations had consistent flows
in mountain refugia.
Failed/Struggling: The Mexican Lifeboat
Species that failed in Arizona (often due to poisoning or
habitat loss) survived in Mexico, which served as the last stronghold.
Masked Bobwhite
Status in Other
U.S. States: Extirpated: Only exists in captivity/refuge.
Status in
Mexico: Critical / Persistent: Small wild populations were rediscovered on
private ranches in Sonora (e.g., Rancho Carrizo) in the late 20th century.
Accounting for
the Difference: Grazing Intensity: While U.S. ranchers switched to exotic
grasses (Lovegrass), some remote Sonoran ranches maintained native vegetation
due to isolation and traditional (lower intensity) grazing practices.
Thick-billed Parrot
Status in Other
U.S. States: Extirpated: No wild flocks in the U.S.
Status in
Mexico: Endangered / Extant: ~2,000 birds breed in the Sierra Madre Occidental
(Chihuahua/Durango).
Accounting for
the Difference: Old Growth Timber: Arizona logged its sky island nesting snags
by the 1930s. The remote Sierra Madre retained old-growth forests longer
(though these are now threatened by logging).
Jaguar
Status in Other
U.S. States: Extirpated: (Breeding populations).
Status in
Mexico: Vulnerable / Breeding: A reproducing population exists in Sonora
(Northern Jaguar Reserve), only ~120 miles south of the border.
Accounting for
the Difference: Road Density: Arizona is crisscrossed by paved roads and
development. The Sonoran habitat is more rugged, roadless, and largely
privately owned, reducing human-cat interaction.
Black-tailed Prairie Dog
Status in Other
U.S. States: Extirpated: Widespread poisoning campaigns.
Status in
Mexico: Thriving (Janos): The Janos Biosphere Reserve in Chihuahua holds one of
the largest prairie dog complexes in North America.
Accounting for
the Difference: Benign Neglect: The U.S. government funded industrial-scale
poisoning. The Mexican government lacked the funds for such programs,
inadvertently allowing the massive colonies to survive until conservationists
bought the land.
Summary of Differences
The Industrial Efficiency of Extirpation
Arizona’s extirpations were often more thorough than Mexico’s
because the U.S. had the resources to be efficient. Government-sponsored
predator control (wolves/jaguars) and poisoning (prairie dogs) were well-funded
industrial operations in Arizona. Mexico, lacking these centralized resources,
allowed "pest" species to survive simply through "benign
neglect."
Public vs. Private Conservation
Arizona: Success relies on public land management (US Forest
Service/BLM). This is great for generalists like elk but hard for specialists
that need specific micro-habitats.
Mexico: Survival has relied on private land isolation. Remote
ranches in the Sierra Madre acted as unintended nature preserves because they
were too difficult to log or develop.
The Elk Gap
The single biggest ecological difference today is elk.
Arizona replaced its lost native elk with a massive, successful herd of Rocky
Mountain elk. Mexico never did. This means Arizona has a massive prey base for
wolves and lions that Mexico lacks, creating a "food imbalance" at
the border that complicates predator recovery in the south.
