FLORA & FAUNA
A GUIDE TO THE WILD LANDS OF RANCHO DE LA OSA & THE ALTAR VALLEY
A GUIDE PRESENTED BY RANCHO DE LA
OSA
rancho de la osa FLORA & FAUNA
A GUIDE TO THE WILD LANDS OF RANCHO DE LA OSA & THE ALTAR VALLEY
TEXT BY NATURALIST JANAY BRUN
EDITING BY DEXTER K. OLIVER
ILLUSTRATIONS BY BRIDGET BRUSSELS
COVER PHOTO CREDIT: SCOTT T. BAXTER
Copyright 2025 Rancho de la Osa
rancho de la osa
A HISTORIC RANCH IN THE ALTAR VALLEY
Rancho de la Osa offers a unique convergence of Native American, Spanish, Mexican, ranching, political and Hollywood history. The land La Osa stands on is home to centuries of history from its origin as indigenous tribal lands to its modern dude ranching history.
Following prehistoric farming cultures, from 300 onward the Hohokam inhabited the area around La Osa; until 1500 when the predominant culture became Tohono O’odham and remains so to this day. The O’odham were living in the area when the Spanish arrived. The Spanish named this region the Primería Alta encompassing the border of western Arizona and Sonora, Mexico.
After years as rangeland and complicated disputes of ownership of the ranch, it became a part of the Arizona Territory with the Gadsden Purchase in 1853. Cattle operations continued well into the ranch’s dude ranching era. The cattle company changed hands several times during the turn of the century between prominent local ranchers and business owners.
In October 1924, John and Louisa Wetherill arrived to La Osa. Louisa Wetherill was an authority on Navajo culture and spoke the language, and operated a trading post and lodge in Kayenta, Arizona. It opened as Hacienda de la Osa on Thanksgiving, 1924, beginning its tenure as a dude ranch.
In its years as a dude ranch, La Osa played host to prominent guests including politicians, Hollywood actors and authors including Lyndon B. Johnson, John Wayne and Zane Grey.
From the 1960s to 1982, the ranch’s ownership changed hands, operating as a cattle ranch or guest ranch. In the spring of 2017, the ranch opened once again to dude ranch guests after Rancho de la Osa was purchased by True Ranch Hospitality and partners. It is now a part of the True Ranch Collection, a selection of historic dude ranches across the West.
“Baboquivari is a granite shaft 7,730 feet high that watches over the United States-Mexican border … The peak has many moods. Mornings when the skies are clear it has a dazzling splendor. By noon the desert dust riding high in the heavens often casts a haze about it. Then its sharp lines are gone and it becomes softer and more remote—a bit out of focus. On a clear day it has a bluish tinge. By midafternoon, when shadows lengthen, Baboquivari seems to tower even higher in the sky. It then turns a dark purple.
Baboquivari’s creation was perhaps fifty million years ago. Once a great volcano probably stood here. Then molten rock welled up in the core of the volcano and hardened into a solid plug. The sides of the volcano weathered and wore off, leaving a pillar of rock. This was millions of years before man appeared on the scene, with his plots and schemes.”
— William O. Douglas, U.S. Supreme Court Justice — “My Wilderness: East to Katahdin,” 1961
Rancho de la Osa is located adjacent to the 117,464-acre Buenos Aires Wildlife Refuge. Known for its high desert grasslands, it also features riparian areas with seasonal marshlands, meadows, cottonwoods and mesquite groves, providing rich habitat for a large variety of wildlife. It’s a birder’s paradise with a tremendous array of species including different orioles, tanagers, herons, ducks and hawks. Though bears and Mexican gray wolves are no longer in the area, mammals like pronghorn, mule deer, mountain lions, and javelinas still roam. There have even been sightings of the elusive jaguar. Discover more with our self-guided hiking map available during your stay at Rancho de la Osa. Wildlife in
Great Horned Owl
MAMMALS OF THE ALTAR VALLEY
JAGUAR
The jaguar is the largest cat species in the Americas. Its presence is constant in portions of Mexico and southward into Argentina. Presently, the cat is rarely detected in the United States and is protected as an endangered species under the U.S. Endangered Species Act.
Over the past 50-plus years, only male jaguars have been detected in the U.S., averaging one to two individuals per decade. One of those males, dubbed Macho B, was first documented in the U.S. in 1996. He was treed by hound dogs getting exercise for future lion hunts in the Baboquivari mountain range, about 20 miles north of Rancho de la Osa. Macho B’s life was almost the exclusive focus of U.S. jaguar research over his 15-year life span. He was documented walking past the iconic saguaro cactus, drinking from a mesquite-rimmed cattle tank, and rolling in a dirt trail that Gila monsters and desert tortoise utilized, too.
As of 2024, there is one jaguar known to exist in the United States. In December 2023, the jaguar, now dubbed Cochise, was videotaped in a mountain range of southern Arizona. This cat was also photographed twice, in March and May of the same year, by remote cameras in Arizona’s Huachuca Mountains, about 150 miles east of La Osa. Coincidentally, the Huachuca Mountains were the location of a shipping container border wall ordered to be built in late 2022 by former Arizona Governor Ducey. The 2023 jaguar photos were taken after that version of a border wall was dismantled just a few months later.
The container wall and the bollard style border wall south of La Osa are prime examples of what threaten jaguar presence and persistence in the United States – obstruction to movement.
BOBCAT
The bobcat is better known as a wildcat in Arizona. This cat is the official mascot of the University of Arizona, and La Osa has a canyon named after it that you will explore on one of your trail rides. The bobcat’s best identifiers are its ear tufts and bobbed tail. The tail can be six to seven inches long. Like its feline neighbors, the bobcat’s fur is customized to blend into the diverse habitats of the Sonoran Desert. At Rancho de la Osa, the bobcat’s fur is typically tawny-grey with the typical black spots on its body and black bars on the legs and chest. This color and pattern combination helps the cat blend into the grasslands and mesquite woodlands of the area. The cat’s camouflage also assists in its hunting technique of stalking and pouncing on its prey.
Jaguar
Because the bobcat can survive in diverse habitats, including urban areas, they are not dependent on one food source for survival like others in their family. For example, the Canadian lynx needs the snowshoe hare, but the bobcat can thrive on a variety of species, from mice to deer. Around La Osa, the bobcat tends to keep a steady diet of cottontail rabbits and wild rodents.
Bobcat kittens can be born year-round with the exceptions of December and January. The kittens remain with their mother for an average of nine months before becoming independent.
According to the Arizona Game and Fish Department, the Arizona bobcat population remains stable. Habitat fragmentation and encroachment remain the biggest threats to the species. Trapping is also a concern for individual bobcats as their beautiful fur retains demand in the fashion industry. The best place to look for tracks on the ranch is the arroyo to the south of the horses’ pastures.
MOUNTAIN LION (AKA PUMA, COUGAR)
Her tawny body slips undetected through the golden grasses of the desert, under the canopy of mesquite, desert willow and hackberry-lined arroyos of La Osa Wash. Her head is small. Her body is short and athletic. Her tail—the rudder—is long and muscular. Though considered a big cat, she is the biggest of the small cats and can meow, chirp, snarl, scream, hiss, and whistle, but not roar. Her kittens, one or more depending on the area’s resources, are born blue-eyed and blind, spotted, and dependent on her for an average of 18 months.
Her mate, in contrast, has no direct involvement in their upbringing. However, they depend on him to maintain dominance in their natal home. He does this through a mutual avoidance strategy of scent marking: claw raking on trees, urinating on vegetation and rocks, and creating mounds of soil and their accompaniments called scrapes that can also be scent marked with their tootsie roll-shaped scat. If he is challenged regardless and loses his territory to another male, sometimes by death, the victor could attempt to sire his progeny with their mother by killing the kittens to bring her into estrus.
Mountain Lion
Bobcat
Mountain lions are opportunistic and mostly crepuscular hunters—stalking and ambushing their prey at dusk and dawn. In Southern Arizona, the cats’ preferred meal is deer, both white-tailed and mule. On occasion, they find a sheep worthy of a meal as one female and her kitten proved at Rancho de la Osa several years ago. The ram was eviscerated but not eaten and it was believed the female lion was teaching her young how to kill.
Mountain lions are able to jump 18 vertical feet, sprint for a short time at 40-50 miles per hour, kill prey larger than them, and thrive in diverse ecosystems across the Americas. But, the cats remain vulnerable to human influences. Examples include habitat fragmentation, encroachment, and destruction, and hunting.
PRONGHORN
Native to the Sonoran Desert that spans the United States and Mexico lives one of five sub-species of pronghorn, the Sonoran pronghorn. It is a distinctive sub-species for several reasons. Mainly, the Sonoran pronghorn is smaller in stature than its relatives up north and lighter in color to blend into the sandy straw hues of the desert landscape. In addition, this subspecies has adapted to the arid climate, but water remains a limiting factor to its survival.
Sonoran Pronghorn
The Sonoran pronghorn population in the U.S. was close to extinction in 2002 due to severe drought, and only 19 of a population of 140 animals were able to survive. After that extreme event, the Arizona Game and Fish Department added water catchments across their range, mainly in wildlife refuges. Osa’s neighbor, the Buenos Aires National Wildlife Refuge, has several catchments that benefit a different subspecies of pronghorn and all their neighbors during the dry times of the year.
Sonoran pronghorn can be found far west of Osa, on the Cabeza Prieta National Wildlife Refuge in Ajo. Their more common relatives, Antilocapra americana americana, were re-introduced on the BANWR, Osa’s neighbor, in the 1990s, and now a herd of over 100 individuals roam the open landscape. Currently, the refuge is working on eradicating mesquite trees that moved into the desert via cattle manure when it was a working cattle ranch. In addition, fire suppression, harvesting of the grasses and cycles of extreme drought and rains allowed the mesquite tree to outcompete the grasses. The transformation back to open grasslands benefits pronghorn by giving them more visibility to spot predators. The pronghorn do not hide from predators but instead outrun them at speeds up to 60 miles per hour. They are the fastest land animals in North America.
Pronghorn have horns like bison and bighorn sheep; but unlike them, they shed their outer horn sheath, made of a substance similar to human fingernails, yearly.
Viewing tip: When visiting BANWR, look for the pronghorn along the main entrance road. Their white rump can stand out first, and then you can spot their tan body. The refuge also has a Pronghorn Drive self-auto tour.
DEER
Two deer species are found around Osa, mule (a.k.a. mulie) and Coues (pronounced cows) white-tailed. Mule deer have large, mule-like ears, a white rump patch, and a black-tipped white tail. The Coues is a distinct subspecies of white-tailed deer known as the “gray ghost” due to their camouflage, timidness and speed. In addition to their signature white tail, they can be distinguished from the mule deer by white halos around their eyes and a white band across their muzzle. The Coues “flag” their white tail when moving away from a perceived threat. The mule deer are the only species that stot away from their predators. This behavior looks like they are jumping up and down on four straight legs. The Coues just run away with speed.
During the warmer months, mulies and the Coues are more active during the night and early morning hours. The Coues can survive for long periods without water.
A Coues buck’s maximum weight can reach 125 pounds on the hoof, while the mule buck can reach 150 to 300 pounds. Both depend on a varied diet of shrubs, grasses, even cacti, in their diet. The mesquite tree’s leaves and beans provide them with a consistent food source around Osa.
Though the Coues deer are associated with higher elevations that favor oak and pine, they also like open grasslands. The mule deer are more prominent in the lowland grass ecosystem. At Osa, both species call the ranch home. A popular place to find a mixed herd is on the ridges south of the cemetery and Pig Rock trail. Though hybridization between the species can occur, biologists who have studied the possibility have concluded it happens but is rare.
JAVELINA
At Rancho de la Osa, a pig-like animal roams the desert in family groups rooting for tubers, munching on prickly pear cacti, fallen mesquite beans and the occasional lizard. Unlike the pig, our javelina have straight, one-inch canines, a short tail, and a scent gland located on top of their butts that can be rubbed on trees as a scent marker or used for communication.
A more official name for the javelina is collared peccary. This hints at the animals’ physical appearance of bearing a collar around their neck and shoulder area because of the lighter hair color contrasting with the salt and pepper pelage of their bodies. The javelina is a stout animal with short legs. Males can weigh up to 60 pounds. They have poor eyesight and great snouts for smell. Occasionally, this gets them in trouble with dog walkers. The javelina smells a predator in the collared dog and theoretically mistakes their canine silhouette for that of a coyote.
Viewing tip: While visiting Osa, look for the javelina’s short, knuckle shaped hoof tracks in the washes and along the dirt roads. Their day beds are found at the base of the mesquite trees that dominate La Osa’s landscape.
Mule Deer
Javelina
GRAY FOX
Stamped in the sandy washes surrounding Osa is a small Christmas tree-like track that indicates the presence of the gray fox. His coat color is loyal to his name, and the tip of his tail is black. He has reddish color on his legs and black around his eyes. In Mexico, he is called zorro.
The gray fox is mainly solitary and nocturnal. Unlike his other canine relatives, he can climb trees. The trees provide safety and shelter for the gray fox and hunting opportunities. As an omnivore, the gray fox’s diet is varied. In the trees around Osa, he can feast on bird eggs, lizards and mesquite seeds. In late summer into the fall, the distinct red and yellow discarded casings of the hackberry fruit can be found in small piles of the fox’s scat deposited in plain view along Pig Rock Trail. The hackberry fruit—born from the gray and thorny desert class evergreen tree popular along the desert arroyos—is also included in the diets of the raccoon, coyote, various birds and squirrels.
Gray Fox
The gray fox can weigh up to 10 pounds and live just as long. The female fox, vixen, stays with the pups in the den, but the male does not enter the den. Instead, he stands guard for predators on a nearby vantage point. Fox pups are born in March or April and are bundles of playful energy that spend their days chasing and tackling each other.
In times of plenty, the gray fox will bury his excess food and mark the cache with urine to serve as an olfactory reminder to find his food in the future.
COYOTE
Coyote is one of the most prolific mammals in the desert. Iconic for their vocalizations, the “song dog” can be heard yipping and howling around La Osa, often at dawn and after dusk. The alpha female and male of the family group are usually the singers and enjoy other perks like being the first to eat and the only pair to mate. Mating occurs around February. The pups are born 60 to 65 days later. The subordinate members of the family help the alpha pair raise the new family members.
Coyotes are probably one of the most adaptable animals in the United States. Their vocalizations can be heard in suburbs, on a city corner or floating from a rural hillside. At La Osa, look for their slim, dark sand silhouettes crossing dirt roads or roaming in the arroyo bottoms. Their tracks are similar to domestic dogs, except they walk with purpose rather than wander about the trail. Also, unlike dogs, the nails of their middle toes tend to register more than the rest in their tracks.
The coyote is classified as a predator by the Arizona Game and Fish Department. Around La Osa, their predation occurs on small mammals like rodents and rabbits, bird eggs, mesquite beans, palo verde pods, and juniper and hackberry seeds.
Coyote is a familiar character in traditional Native American stories. In this area of Arizona, several Tohono O’odham tales feature him stealing and then spilling white tepary beans or flour in the sky during his getaway to create the Milky Way. In addition, the coyote is part of the Tohono O’odham’s creation story. Coyote was made in the second stage of creation along with the Moon, Milky Way, and Buzzard by Earth Doctor and Elder Brother.
A flood destroys the first stage of creation. Earth Doctor, Coyote, and Elder Brother, later known as I’itoi, survive. Earth Doctor returns to the heavens, but I’itoi and Coyote remain on Earth. Both survivors endure to this modern day. I’itoi lives in his cave below the granite dome of Baboquivari Peak, and Coyote lopes in and around O’odham lands, including La Osa.
JACKRABBIT
The antelope and black-tailed jackrabbits are the resident hares of Rancho de la Osa. The black-tailed is slightly smaller at around eight pounds and distinguished by black edging along his ears and on the tip of his tail. The antelope jackrabbit mimics the pronghorn antelope coloring by having white flanks and can weigh in at a hefty 10 pounds. Both use their large ears as heat vents. Since they don’t drink much water, their ears’ blood vessels act as regulators and can release excess heat from the animal’s body.
Both species of jackrabbit are present on Osa’s lands and our neighbor, the Buenos Aires National Wildlife Refuge. In the shade of cacti and under the mesquite tree canopy that borders the area’s arroyos are the most popular places to look for the hares. They tend to be most active at dusk and dawn, known as crepuscular, but can also be active under the night sky. When on alert, the jackrabbit will stand up on its large hind legs. If threatened, the jackrabbit will either flatten against the ground and freeze (antelope) or leap into 15-foot bounds at speeds reaching 35 miles per hour (both).
Like all hares, jackrabbits give birth to furred and open-eyed young. They enjoy an herbivore diet of various types of grass, the beans of acacia and mesquite trees, prickly pear cacti, and twigs.
SKUNK
The desert has four types of skunks; but around Osa, only three have presented themselves: hooded, striped and hog-nosed. The skunks are omnivores and eat anything from birds to mesquite seeds, bugs, worms, carrion and small rodents. All three of our skunks are ground dwellers. Only the spotted skunk—not usually seen around Osa—climbs trees.
Of course, they all resemble each other with black and white markings. This color cue serves as a visual warning to predators. The striped skunk has the classic black body, usually with a white stripe down its upper sides or back area—though not guaranteed—and always one on its face. In addition, their tails are roughly the same length as their body. The hog-nosed is the stockiest, with a black body and wide white stripe covering its back and swallowing its short tail. Their naked, hog-like noses and long claws make them the best diggers of the bunch. The hooded skunk differentiates itself by having a tail longer than its body and extra fur around the neck. This skunk’s color variations can resemble the striped or hog-nosed and also has a white stripe on its face.
All the skunks have a sulfur-based defense mechanism. They can aim their spray up to 15 feet away, and the scent can drift for over a mile. The great horned owl is the primary predator of skunks. This owl has poor smelling ability, and the skunk’s defense mechanism is no deterrent to becoming the bird’s meal.
Skunks find homes under logs and brush, buildings, and sometimes dig burrows and will share them with their kind or even packrats. Two hooded skunks decided to burrow in Osa’s cantina during the 2023 holiday season. They acquired a taste for wine and tequila before they were evicted!
Jackrabbit
BIRDS OF THE ALTAR VALLEY
CACTUS FERRUGINOUS PYGMY OWL
The Cactus Ferruginous Pygmy Owl is a subspecies of the pygmy owl. A short and feisty raptor, the owl stands at six inches tall and is found in Southern Arizona and Texas, and northern Mexico.
In 2023 the owl was re-listed under the U.S. Fish and Wildlife Service’s Endangered Species Act as a threatened species. The owl had previously been listed as endangered in 1997 but then was de-listed in 2006 because the species was seen as thriving in Mexico at the time.
The owls utilize saguaro cacti and mesquite woodlands habitats. They do not migrate or fly long distances. This makes them vulnerable to threats such as habitat loss and degradation, a warming climate, and invasive species. In Arizona, the majority of the owls’ range is now limited to the Altar Valley where Rancho de la Osa sits on its southern boundary.
The United States Fish and Wildlife Service, Arizona Game and Fish Department, Phoenix Zoo, and Wild at Heart Rescue have worked together since 2018 to breed these owls in captivity to be released into the wild.
Cactus Ferruginous Pygmy Owl
Rancho de la Osa is a part of the effort to help bolster the owl population in their native range. After the owls are transferred into the mesquite woodland aviaries, they are fed and watered every day by a third party. They are also remotely monitored by biologists through cameras placed in the aviaries to study their behavior. The owls remain in their acclimation pens for ten days before release. Their whereabouts after that are monitored by tracking devices and call surveys done by an AZ Game and Fish Department biologist.
GREAT HORNED OWL
Hoots and honks of a great horned owl pair can be heard in a back-and-forth mating song across Osa’s zócalo in late winter. The tall eucalyptus trees make for the perfect stage for them to serenade one another and quickly mate. The female is larger than the male, but he has a louder voice. The trees also provide the monogamous pair cover and launching sites for their hunting forays year round. They are fierce predators, dining on mice, rabbits, insects, and other birds, including hawks.
Great horned owls use the former nests of ravens and hawks. Behind Room One is a large nest high in a pine tree’s canopy that the owls and ravens have swapped over the years. The female and male take turns incubating the eggs. The owlets hatch roughly 40 days later, blind and helpless.
Though associated with the night, the owls can also be active during the day. Look for songbirds and ravens making a racket in a tree, and more often than not, a great horned owl is probably the reason for the noise. The other birds do this to harass the predators and get the owls to move on.
Viewing tip: While enjoying a hike or trail ride along the ranch’s arroyos keep an eye out for the large, ear tufted, great horned owl. They also roost in mesquite trees and will silently (due to their insulating feathers) fly away to another roost if disturbed.
GREATER ROADRUNNER
Beep! Beep! This famous cuckoo of the Southwest has various sounds like clacking, hooting and a guttural coo that the cartoon version never vocalized. But, in an homage to its cartoon nemesis, the roadrunner makes a “sharp barking call” that sounds like the yip of a coyote.
At Osa, look for roadrunners running—up to 15 miles per hour—or awkwardly flying across the dirt roads and arroyos of the area. The semidesert mesquite grasslands of Osa provide the birds with cover, nesting sites and food sources for their survival. Their diet consists of lizards—which they beat against a rock to break the bones for easier digestion if it’s too big—scorpions, cactus fruit, seeds, snakes (including rattlers) and birds like baby Gambel’s quail. Mesquite trees and cholla cacti furnish nesting sites, and the landscape provides an open hunting ground with shaded cover.
Like all desert dwellers, the roadrunner has adaptations to survive. To conserve water, the roadrunner secretes a concentrated salt solution through a gland near the eye rather than having to excrete it through the kidneys and urinary tract. Roadrunners also flutter the featherless area under their chins for heat evaporation. Their diet aids in adding water to their systems.
Greater Roadrunner
Look for the “X” shaped track of the roadrunner in the sandy washes around Osa, and place a bet with your walking partner on which direction the bird went.
TURKEY VULTURE
The turkey vulture floats and rides the thermals above Osa in its distinctive swaying V-wing formation daily. The turkey vulture uses its outstanding sense of smell to locate food, preferably fresh carrion.
Turkey vultures are the primary custodians of ecosystems across their range due to their powerful stomach acid. This liquid enables them to feast on just about anything, including diseased carcasses tainted with rabies, anthrax and tuberculosis. Their wide-ranging diet aids in keeping the environment clean and healthy for its neighbors, including humans.
The turkey vulture has a few ways to regulate its body temperature. One method is to defecate on their feet to cool off. They also greet the day by standing in trees with their wings spread like Dracula to warm up or cool off.
BLACK VULTURE
At Osa, we are fortunate to have an additional vulture species, the black vulture. Unlike the turkey vulture, this bird does not have a great sense of smell and adapts by soaring above the turkey vulture to follow them to carrion. The black vulture also hunts lizards and small mammals and will scavenge at garbage dumps.
This distinguished-looking vulture has no voice box. Their vocabulary is limited to grunts and hisses, with juveniles resembling a demon from a fairytale.
Black vultures are monogamous and have strong familial bonds. Like turkey vultures, they share a communal roost at night and spread their wings in the morning light to regulate their body temperature.
GRAY HAWK
In early March, the distinctive high-pitched “cree” sound of the gray hawk returns to Osa. The gray hawk is a tropical species that migrates to limited areas in Arizona and Texas. They were common in Arizona in the 1800s. However, the consistent clearing of their preferred habitat in cottonwood and mesquite-lined riparian corridors and the depletion of groundwater contributed to their decrease in numbers.
Gray hawks are small raptors painted in light to metal gray with a banded chest and a slim dark gray and white striped tail. The majority of their diet consists of lizards. Coincidentally, their Arizona territories overlap with those habitats that support a high density of lizard species. They also may dine on small birds, rodents and an occasional rabbit.
Gray hawks can be seen soaring during the day. Their popular routes above Osa include the pool, the corral, and in-between the eucalyptus trees that line the ranch’s zócalo
CRESTED CARACARA
This striking tropical falcon has a chocolate-colored body with white patches on the tips of its wings, a narrow, whitish tail base, a white face capped with a dark crown, and an orangish-red base at its bill. The crested caracara, sometimes called the Mexican eagle, is a typical presence south of the border but is found in only three states in the U.S.: Arizona, Texas and Florida.
Crested caracaras are omnivores but also scavenge from carrion, frequently alongside vultures. Adjacent to Osa property in 2024, a cow died while giving birth. Though bird books speak to the crested caracara chasing vultures off carrion, in that instance, the falcon was outnumbered twelve to one. As a result, the crested caracara was excluded from the feast until the turkey and black vultures finished their meals. But, as also attributed to the caracara, perhaps he later harassed a vulture to the point where it regurgitated its food, providing a meal for the falcon.
The caracara is the only falcon to build a nest, and the breeding pair becomes loyal to that nest site in subsequent years.
Viewing tip: While at Osa, look for the crested caracara perched on high branches, especially in Sasabe wash along the loping trail. En route to or from Rancho de la Osa and Tucson, look for the breeding pairs of crested caracaras in the saguaros by Anvil Ranch just west of Highway 286 and in the saguaros by Ryan Airfield north of Highway 86.
Crested Caracara
TYRANT FLYCATCHER
The biggest family of birds in the world is the tyrant flycatcher, which has 400 species. The Say’s phoebe and vermillion flycatcher are the prominent representatives of this family found at Osa.
The sparrow-sized Say’s phoebe likes to spend the winter at Osa perched on the hacienda’s light posts and handrails. The bird’s color is a muted greyish brown with a peachy-cinnamon stomach. The Say’s phoebe pumps its long, slender tail while preparing to launch into the air to hunt insects on the wing. Bonded breeding pairs defend their territory, and the male escorts the female to potential nesting sites. These include outdoor light fixtures and porch eaves around the hacienda.
This phoebe breeds further north than any other flycatcher, perhaps because it has such a long history in its northern range. Paleontologists have discovered Say’s phoebe fossils in Arizona, New Mexico, Texas and California that date back 400,000 years.
Before the vernal equinox, the vermillion flycatcher returns to the ranch. The male is a brilliant orangey-red color, and the female resembles its relative, the Say’s phoebe, greyish with a brush of a peach shade on the stomach. The color difference is due to sexual dimorphism, a rarity in the North American flycatcher family.
The vermillion flycatcher flits from the ocotillo and barbed wire fences behind the eastern and western wings of the guest rooms. The birds also use the low branches in mesquite trees that border the hacienda for their launchpads.
Their short hunting flights are known as “sallies.” The vermillion flycatcher song, only sung by the male, resembles the cartoon Woody the Woodpecker’s voice.
GILA WOODPECKER
One of the nosiest feathered inhabitants of this region is the Gila woodpecker. The bird’s call resembles a dog’s squeaky toy echoing among the mesquite trees that inhabit the ranch’s lands. This woodpecker species is between a robin and a crow in size, with black and white striped wings attached to a grey body. The males have a distinctive red spot on the crown of their heads. Their flight pattern resembles a bird hopping from one invisible hill to the next.
In the Sonoran Desert, the Gila woodpecker is best known for excavating cavities in saguaro cacti for nesting sites. The hole drilling begins mid-winter, and the resulting cavity is for the cactus pulp to dry and harden. The new nest site is used months to a year later for one breeding season and then abandoned. The cavity can then become home to the cactus ferruginous pygmy owl and cactus wren, among others.
Look for this bird around its other favored nesting sites available at Osa, mesquite and Palo Verde trees—the trees with green trunks.
Gila Woodpecker
PHAINOPEPLA & DESERT MISTLETOE
The phainopepla is a striking bird, glossy black for males and slate grey for females. Both sexes have white patches on their wings that are visible in flight, head crests, and red eyes. Think of a darker-colored version of a cardinal. This unique bird lives and breeds among the mesquites at Osa and feeds primarily on desert mistletoe berries. This berry is the bird’s primary source of water. The phainopepla can mimic the sounds of other birds like their fellow Osa neighbors: Gambel’s quail, mourning doves, northern mockingbirds and red-tail hawks.
Desert mistletoe is abundant in the tree canopy at Osa. From a distance, the mistletoe appears to be a bird’s nest. On closer inspection, the plant is a mass of evergreen stems with pinkish berries. Like other mistletoes, the plant is parasitic. Over time, desert mistletoe will kill its host, most likely mesquite or palo verde around Osa, by feeding off the tree’s nutrients and moisture.
Viewing tip: Look for the striking phainopepla and desert mistletoe at the ranch’s main gate, by the horse corrals, and along the arroyos that weave through the ranch’s land.
BROAD BILLED HUMMINGBIRD
In March when the California poppies are beginning to color the spring landscape gold, the hummingbird feeder gets hung in the hacienda courtyard for the arrival of the first colibrí. The inaugural visitor is the shimmery green and blue-throated male broad-billed. The homemade nectar (one part sugar to four parts water) is an additive or supplement for the ocotillo, desert honeysuckle and desert willow blooms that may or may not be available to the birds after their northern migration. Like most hummingbirds, the broad-billed feast on insects too, and love a good bath in the courtyard fountain.
Broad Billed Hummingbird
After the female broad-billeds arrive, courtship will soon begin. The male woos the female with an arced flight, swinging back and forth in front of her while vocalizing before giving chase. Once mating occurs, the male leaves the female to raise their young. She will build a small, cuplike nest from available vegetation and mortar it with spider webs. The standard two chicks will incubate for roughly two weeks before hatching. At Osa, look for the female’s nest in low-lying mesquite branches that line Pig Rock and the loping trails.
GAMBEL’S QUAIL
Osa’s most recognized neighbor is the black-plumed Gambel’s quail. Both sexes are grey, with buff-brown, cream, and rust colorings. The male has a distinctive black patch on his belly. The quail live in groups known as coveys. These social and plump birds feed on hackberry seeds, cactus fruit and green vegetation in the washes bordering the ranch. While the covey dines, one quail stands sentry on a fence post or tree limb as a lookout.
When coveys flush, they run before spreading their wings to fly low over the ground. This quick flight sounds like a revved-up whir. This quail’s “ca-caw” song is heard regularly in the arroyos around Osa at dawn and dusk.
Gambel’s begin their mating season in the spring. The clutch hatches roughly a month later. But before it does, the female vocalizes to her chicks. They, in turn, chirp to each other to synchronize their hatch!
Gambel’s are almost exclusive to the southwestern U.S. and northern portions of Mexico. The exception is Hawaii. Decades ago, this quail was introduced as a game bird to all the Hawaiian islands by their Game and Fish Department. A few still survive on the Big Island, as well as two others.
MASKED BOBWHITE QUAIL
The masked bobwhite quail is a subspecies of the northern bobwhite native to the Sonoran Desert. The males have a cinnamon breast with a black head and throat and white stripe from the edge of the eye down to the neck. The females are colored in subtle buff, mottled earth tones and have a white stripe originating from the side of the eye.
This quail subspecies is a listed endangered species and the sole reason Osa’s neighbor, the Buenos Aires National Wildlife Refuge, exists. In 1985 the Department of Interior purchased the former cattle ranch exclusively for masked bobwhite quail recovery. The quail’s historical range had been from southeastern Arizona to northern Sonora, Mexico. Over the years, the once open, lush grassland had degraded to a mesquite-dominated landscape because of drought and livestock. The masked bobwhite was presumed extinct in the U.S. by the 1920s. Some individuals still lived in Sonora and were the impetus for attempting to restore the quail to U.S. lands. The first attempts occurred in the ’70s and ’80s. There was some success, but ultimately, the reintroduction program failed due to poor land management.
In addition to seeding, erosion control and prescribed burning, the refuge has been mechanically removing mesquite trees to open the land back up for grassland restoration to aid masked bobwhite recovery. Since the ’80s, BANWR has run a breeding and reintroduction program for the quail. BANWR has a breeding facility in nearby Arivaca and also receives chicks from a facility in Oklahoma.
Masked bobwhite chicks are fostered by a northern bobwhite (captured wild in TX and OK) male because they are more common. Before their release into the wild, the foster dad and his chicks live in an outdoor acclimation pen. Upon release, the foster dad continues to educate the young birds on where to find shade, shelter from predators, and where and how to hunt for food.
The quail can be observed in a public acclimation pen on the BANWR Visitor Center’s Ranch Loop Trail.
Masked Bobwhite Quail
REPTILES & AMPHIBIANS OF THE ALTAR VALLEY
CHIRICAHUA LEOPARD FROG
This stocky frog has a cream underbelly and green back with black spots and some variation of brown splotches, particularly around the legs. The males of this species have a distinct call. They can be audibly identified if the natural camouflage of their skin works too well against visual observation—the frog’s call sounds like a snore. The snore serves two functions for the male: to attract a mate and defend his mating site against competitors. The frogs can also vocalize their call underwater.
Chiricahua Leopard Frog
The Chiricahua leopard frog requires a permanent, welloxygenated water source for survival. This primary need is getting harder to locate in a drying climate. Drought, disease, invasive species, habitat loss and fragmentation are the main threats to the species and why it was listed as threatened under the U.S. Endangered Species Act in 2002.
Rancho de la Osa sits in one of the frog’s native ranges that extends to southwestern New Mexico and across three Mexican states, including our southern neighbor, Sonora.
Currently, the Phoenix Zoo and other conservation partners are working to restore the species to its native habitat. Buenos Aires National Wildlife Refuge has a stock tank habitat for the frogs that can be viewed at their visitor center. Rancho de la Osa also hopes to become a part of the frog’s conservation story with the completion of “Paul’s Pond.”
LIZARDS
In the desert surrounding Osa, there are various species of lizards. The zebra-tailed and whiptails are the most common lizards encountered on the trails and in the washes.
The zebra-tailed is noticeable because of its black and white banded tail. When this lizard encounters a predator, she will wave her tail to focus attention on it instead of her body. The tail is detachable and capable of regenerating where its body is not. This little lizard enjoys the taste of insects and is a fantastic climber and fast—capable of speeds up to 18 miles per hour.
There are several species of whiptails at Osa, but they are all slender and fast with long skinny tails that are longer than their bodies. Whiptails blend into Osa’s environment due to their colors matching the sand and soil of the desert. They have spots and stripes that can be white or yellow and dark patches on their throats and forelimbs. The Sonoran spotted whiptail is one of the 60 percent whiptail species that can produce asexually. The unfertilized eggs hatch clones of the female. That local population is genetically identical. Like most lizards, the whiptail and zebra-tailed will do push-ups to assert dominance over another lizard.
The Gila monster is not a common visitor at Rancho de la Osa but deserves a mention. It is the only venomous lizard native to the United States and is one of two found in the world. The venom is released through special glands into grooves on the lower teeth and then chewed into the victim. Once the Gila monster is attached to a predator, it won’t let go. A human has to work incredibly hard to get bitten by this lizard.
The Gila monster is peachy-orange with black bands and beaded-looking skin. It is a stout lizard that is slow in movement and shy in character.
The Gila monster digs its burrows for hibernation and shelter from the heat, spending 90 percent of its life underground. This lizard hunts by sticking out his tongue to scent the air for prey like rodents, eggs, birds, insects and other lizards. The Gila monster is adapted to live in the desert’s arid environment. The tail can store fat for lean times, hibernation and pregnancy. The bladder can store water that is reabsorbed by the body when needed. And the lizard has a slow metabolism.
The Tohono O’odham believe the Gila monster has the power to cause sickness. Western medicine has researched and used the lizard’s venom for medicine to treat Type 2 diabetes.
Viewing tip: The best places at Osa to look for the Gila monster are on dirt roads and Sunset View Trail from March to November.
SNAKES: COACHWHIP & RATTLE
The unofficial hibernation season for snakes is from mid-November until March 15. But, anytime the temperature rises above 68 degrees, snakes can come out of their dens to sun themselves. Research has found that snakes that sun themselves in winter tend to be juveniles or are sick. The sick snakes are possibly using the sun to warm their bodies and fight off infection. There are two common snakes at Osa: the coachwhip and the rattlesnake.
The coachwhip of our area is usually a vibrant peachy-pink color with tan or black adornments. This snake is thin, long—up to eight feet—and fast, clocking in at speeds of 3.6 miles per hour! The coachwhip is an excellent climber and non-venomous. The coachwhip dines on rodents, birds, and other snakes, including rattlers. This snake is often seen in the spring, crossing the sandy roads that lead to Osa.
At the ranch, two varieties of rattlesnakes make their presence known through their warning buzz: the western diamondback and the Mohave. The western diamondback is stocky and has a diamond pattern on its back with a black and white banded tail. The Mohave rattlesnake looks similar to the diamondback but has a greenish tint to its body. Both snakes have a triangle-shaped head and are pit vipers with heat-sensing loreal pits behind each nostril to detect temperature differences. The pits assist with hunting as both snakes are ambush hunters. They feed on rodents, birds, lizards and other snakes. The snakes’ rattles are keratin, the same substance as human fingernails.
At the hottest part of the day, the rattlesnakes will find shelter in the shade of vegetation, wood piles, rock shelfs or animal burrows. In the cooler months, the diamondback hibernates in large groups. Sometimes, den mates include the desert tortoise and Gila monsters. The Mohave prefers to den alone or with a few others of its kind.
The Mohave has unique venom in that it contains neuro and hemotoxins. The diamondback’s venom does not contain neurotoxins. The Mohave is known to be the more defensive snake of the two. If encountered, leave the snakes be. Seek medical care immediately if bitten.
During the mating season, the males of both species dance with other males of their kind in a “combat dance.” This sinuous dance is one male trying to overpower the other for mating privileges. The female gives birth to live, venomous young in late summer.
Wear proper footwear and long pants when hiking in snake country, and take extra caution on the trails during warm morning and evening hours.
insects OF THE ALTAR VALLEY
PINACATE BEETLE
Common among the landscape and surrounding lands of Osa is the pinacate beetle, a small black beetle that walks with his head down. When threatened, this beetle earns one moniker, clown beetle, by doing a headstand and secreting a foul-smelling oil from his abdomen that earns this beetle yet another name: stink bug. This defense mechanism fends off some predators, but the grasshopper mouse is unfazed. The rodent will grab the pinacate beetle and bury his abdomen in the sand to avoid the foul odor while beginning to feast on his head!
The pinacate beetle is part of the decomposition force that defines the beetle family. Using their antennae, they locate and feed on animal and plant waste, helping to clean the environment. In addition, the beetles use their antennae to find mates, detect egg-laying sites, and gauge temperature and humidity. The beetles are active any time of the year but prefer to wait out the day’s heat in cooler burrows dug by other animals. Though the beetles have wings, they do not fly. However, their wing covers serve as heat and water loss insulators.
Viewing tip: Look for these humorous bugs on Osa’s horse and hiking trails.
BARK SCORPION
The small bark scorpion is the most venomous in North America. At Osa, we are fortunate to host this species under rocks, in lumber piles and underneath tree bark. The scorpion prefers dark and damp spaces. A nocturnal arachnid, the scorpion glows a greenish blue under UV light.
This scorpion is the color of sand, and its tail resembles five grains of rice strung together and topped with a stinger. The bark scorpion eats insects, spiders and even other scorpions. They can live up to six years in the wild and prefer to hibernate during the winter months in large groups. The females give birth to live young that she carries on her back until their first molt up to three weeks later.
Osa’s environment is full of beautiful rocks. Be careful of the bark scorpion if you pick one up. And please practice Leave No Trace principles, particularly number four: “Leave what you find.” Taking one rock is enough to disrupt the environment in which it lives and exposes the soil to degradation and erosion.
Pinacate Beetle
flora of the Arizona Borderlands
The unique high desert grasslands surrounding Rancho de la Osa have changed with the centuries, especially due to suppression of natural fires and the Spanish introduction to cattle to the area. Today the landscape is dotted with mesquite and other larger tree species, where native grasses once would have dominated. In riparian areas, wet marshes and meadows allow for cottonwoods and hackberry to thrive. The mountainous landscape includes elevation changes suitable to varied plant life. Quintessential Sonoran Desert cactus species also dot the landscape, with its iconic backdrop of the Baboquivari Mountains.
Prickly Pear
PLANTS OF THE ALTAR VALLEY
SAGUARO
The iconic columnar cactus most associated with the desert landscape is the saguaro. A slowgrowing cactus, the saguaro produces its arms at 50 to 70-plus years, but some may remain armless, known as spears. The cacti live between 150 to 200 years old and are endemic to the Sonoran Desert. In death, saguaro ribs can be repurposed as building materials. Examples of this at Osa are ceiling coverings and window shutters found in various guestrooms.
The saguaro is most associated with the monsoons of the Sonoran Desert. The local indigenous nation, Tohono O’odham, begin their calendar year in May or June with the harvest of the saguaro fruit using saguaro ribs, in part, as a tool to knock the fruit off the cacti. In July a portion of the harvested juice set aside to ferment into wine is drunk at the Navai’t ceremony to welcome in the new year and the upcoming monsoon rains.
A mature saguaro cactus can soak up to 200 gallons of water during a monsoon rain. The water deluge causes the plant to expand and appear bloated. During dry times, the cactus loses its water weight and shrinks. Saguaro flowers are a food source for pollinators that include bees, insects, the lesser long-nosed bat, moths, and most importantly, the white-winged dove, which time their migration to the flowering of the saguaro.
In addition to being an important food source for the humans and flora of the Sonoran Desert, the saguaro provides nesting sites for a variety of birds. The Gila woodpecker is the original architect of the saguaro home, drilling a nest cavity every season. Their old nesting cavities, in turn, become the new homes for other species like the cactus ferruginous pygmy owl.
There are just a few saguaros at Osa due to our colder temperatures, and they live among the rocky ridges along Pig Rock Trail. On the warmer western side of the neighboring Pozo Verde mountains, saguaros are abundant. The Presumido Pass UTV tour drives through this saguaro community providing an intimate look at the cacti the Tohono O’odham consider their elders.
OCOTILLO
This spiny, long-branched plant is a stunning example of the transformative power of water. Within a week of good rain, the bare, gray stems turn green and produce tiny, emerald-colored leaves along their stems. Then, the tops of these whip-like branches produce flowing fire redorange tubular flowers that attract diverse pollinators, including hummingbirds. The ocotillo’s flowers represent another name for this plant, “flaming sword.”
Though the ocotillo has spines, it is not a cactus but a drought-deciduous shrub. It may grow to 20 feet tall and produce up to 75 branches. Ocotillo can be found wild on the hilltops surrounding Osa and as a fence-building material behind the guest wings flanking the hacienda and around the cemetery.
Saguaro
PRICKLY PEAR
One of the most prolific and symbolic plants associated with the Southwest is the prickly pear cactus. There are 18 prickly pear species, and two dominate the landscape around La Osa, Santa Rita and Engelmann’s.
The prickly pear is an important food source for wildlife and humans. The young pads or nopales of the cactus are stripped off its spines by humans and then sautéed, boiled, or grilled. Javelina also enjoy a meal of raw nopals, and their teeth marks are evident on the cacti edges. Cattle seem to gravitate toward the cactus when grass is unavailable on the range.
The deep purple fruit, or tunas, can be eaten raw or cooked for a jelly or syrup that livens up lemonade and margaritas. One has to overcome the desert tortoise, birds and insects to harvest the fruit first. Prickly pear seeds are also nutritious. The whole plant is a good source of fiber and may lower high blood sugar.
The prickly pear cactus is susceptible to cochineal scale bugs. These insects create a white, cotton-like substance to shelter the female bugs and eggs. This mass turns a vibrant red color when crushed or rubbed. The cochineal mass is coveted as a food and fabric dye.
CATCLAW ACACIA
Prickly Pear
This small, semi-deciduous tree has vibrant green leaves that color the sun-filled arroyos around Osa. In the spring, its yellow catkins blanket the arroyos with an intense, sweet aroma. Pollinators are attracted to this scent, and the tree’s nectar is an important food source for bees, butterflies and beetles.
This acacia is drought tolerant and can withstand the temperature extremes in the desert: the highs of the summer in the 100-plus degree range to the lows of winter dipping into the teens.
As its name suggests, the thorns on this tree resemble cat claws and are easy to get clothing and skin snared in if one gets too close. Be aware when hiking around Osa, particularly on the Pig Rock trail.
Indigenous peoples have used this tree for its wood and medicinal value. The local Tohono O’odham has used the tree’s roots to make tea to address stomach and kidney complaints.
In the southwestern United States, there are several native mesquite varieties: velvet, honey and screwbean. In the Altar Valley—home to Rancho de la Osa—velvet mesquite dominates. This shrub-small tree variety is well-adapted to the arid climate of the region. Their roots grow deep and wide and are indicative of groundwater conditions.
The mesquite is an integral part of life for myriads of species. Pollinators, especially bees, are attracted to their flowers and create delicious, amber-colored honey. Wildlife species depend on mesquite pods for food and the tree’s canopy for nesting sites and shade. Humans also utilize mesquite beans as a food source, particularly as flour. The leaves, twigs and bark can be included in medicinal preparations, like a wash, to address various ailments such as itchy eyes and skin irritations. The most common human link to mesquite is through its wood—as a building material, firewood and charcoal to create the quintessential flavor of Southwestern cooking.
Rancho de la Osa and the Altar Valley were once a landscape dominated by perennial grasses. By the late 1800s, the valley’s grasslands were transforming into a semi-desert grassland community dominated by the mesquite. The causes of this change can be attributed to overgrazing by livestock, drought and fire suppression.
Today, neighboring ranches and the Buenos Aires National Wildlife Refuge are using mechanical means to remove the mesquite to revert the land to a perennial grassdominated landscape. This restoration effort is a living experiment. Wildlife and plant species have evolved with the mesquite-dominated ecosystem for over a hundred years. What will be the short and long-term consequences to the land and wildlife communities because of the artificial shift to another habitat type in an ever-shifting climate?
FISHHOOK BARREL CACTUS
Among the hills and washes of Osa, a stout, medium-height—up to 11 feet—cactus referred to as a barrel or compass barrel stands sentry among the mesquite trees and prickly pear cacti. As the moniker “compass” hints, this cactus can be used as a direction guide as it typically points to the south or southwest. The top of the cactus sometimes resembles a spiral because the fishhook barrel leans toward the direct sun.
The yellow fruit of the cactus can be present year-round. It is a food source for birds, wildlife and humans. Barrel cactus candy has a flavor reminiscent of watermelon, and the fruit combined with desert rhubarb stalks and chiles creates a lively relish.
The insides of the barrel cactus do not contain water but rather an oxalic acid that can cause kidney stones and diarrhea.
As the name implies, the spines of the fishhook barrel cactus were used as fishhooks by Native Americans.
Fishhook Barrel Cactus
YUCCA
At Rancho de la Osa, two species of the yucca plant are present: the banana and soaptree. Look for either along the Pig Rock and Sunset View trails. They are in the agave family, and both produce stalks, with the soaptree producing the higher of the two at up to 30 feet. Both yuccas have pointed sword-like leaves. The banana yucca produces fruit that resembles bananas and is delicious to eat. The flavor is reminiscent of a creamy sweet potato. The soaptree has a wispy appearance with threadlike material coming from the edges of its leaves. This yucca tends to grow in clumps.
The roots of both yuccas can be dried and used as a soap substitute. Their leaves were also used by Native Americans to create baskets.
The yucca plants would not exist without the yucca moth. The yucca depends on her for pollination, and the moth relies on the yuccas for food and shelter for the next generation.
AGAVE
Two distinct plants adorn the front steps leading to the hacienda. They are blue agave, Agave tequilana. As their name suggests, they are the plants used to create the liquor. Tequila production begins with the plant’s harvest at seven or 14 years of age. Next, its core or heart or piña is stripped of its leaves and roasted to convert sugars. Next, the roasted piña is pressed free of its clear liquid known as honey water, agua miel, before being fermented and distilled into tequila. The sotol or desert spoon is another agave variety found at Osa that produces a popular liquor.
Agaves are distinguished by their succulent or semi-succulent leaves, which are usually lined with teeth and come to a strong point. Another agave species found on the ranch’s higher lands, the shindagger, demonstrates this characteristic in a painful manner to uneducated hikers.
Agaves produce stalks of varying heights starting at 10-plus years old. The stalks form a branched or unbranched inflorescence. Most species of agave will die after this process, after using all their energy to produce their flowers. The agaves that open their flowers at night are white or yellow. These varieties are a vital food source for bats, especially during migration. Hawk moths and bees also enjoy their nectar and pollen. The agave varieties that open their flowers at sunrise and sunset are for the hummingbirds, insects and bees.
Indigenous communities have used the agave plants for thousands of years. Two communities that once lived at Osa and in its environs, the Hohokam and Tohono O’odham, used the agave for food, fiber, clothing and medicine. The O’odham also produced a traditional alcoholic drink from the agave called tesgüino.
