NORTH AMERICAN SONORAN DESERT Part 1

The Sonoran Desert is the most biologically diverse of the four North American deserts covering 120,000 square miles (310,800 square km) of southwestern Arizona, southeastern California, and the Mexican states of Baja and Sonora. A diversity of habitat that includes mountains, rivers, and canyons provide luxurious habitat for numerous unique species specially adapted for heat, aridity, and intense summer monsoons. More than 100 reptiles, 2,000 native plants, 60 mammals, and 350 birds call this desert home.

I was first introduced to the Sonoran of Baja, California Mexico through Lindblad National Geographic where I was trained as a naturalist aboard the ship Majestic Explorer. We completely circum-navigated the Baja Peninsula, and rubbed elbows with the late Dr Archie Carr, world famous sea turtle biologist acting as chief naturalist on board. I was introduced into the rich ecosystem of Baja, and the rich and diverse Sea of Cortez, one of the most diverse marine ecosystems in the world.

Following Baja my parents retired and moved to Tucson Arizona from Seattle. They both loved exploring the Southwest and the Anasazi culture expressed through the Navajo, and journeyed four wheeling into remote sections of Canyonlands, and hiking their beloved Sajuaro National Park and Sabino Canyon, a tributary of Mt Lemon. I came to visit them often, in spring, summer and winter and through the Desert Museum staff I came to know, learned of its diversity. My father spent his last months in Tucson afflicted with the final stage of brain cancer, and I was there to pray and be with him in his last few weeks. I would return to their home in the evening and recall walking nearby Sabino Canyon many times to refresh myself from long visits to the hospital, listening to both morning and evening calls of doves, mockingbirds and cactus wrens. My father went home to be with the Lord and my mother remained in Tucson a few more years, and we did some day hikes together, including the remote chiricahua mountains, the last stronghold of the Apaches. My parents not only encouraged me with a deepened faith in Jesus

Christ facing death with great joy, but also fond memories of sharing their love for the summer the desrt, its monsoons, and dads love for photographing the Sajuaro cactus forest, mountains and spring flowers at his backdoor.

The Sonoran Desert is somewhat diverse ranging from the Southwest into northern Sinaloa and Baja Mexico. It is known to have a subtropical climate with 3 to 15 inches (75 to 380 mm) of rain per year, most of it occurring during the monsoon season (July–September), when strong, brief thunderstorms bring heavy rain. The hottest and driest part of the desert is near the lower Colorado River, where summer temperatures can reach more than 120 °F (49 °C) and rainfall is less than three inches.The semiannual rainfall pattern produces a high biological diversity. Winter storms from the Pacific nourish many West Coast annuals such as poppies and lupines, while well-developed summer monsoons host both annuals and woody plants originating from the south. Freezing conditions can occur for a few nights in winter.

The vegetation of the Sonoran is the most diverse of all the North American deserts. In addition to the saguaro cactus, the signature plant include the barrel cactus, organ-pipe cactus, prickly pear, cholla, ocotillo, yucca, century plant, ironwood, palo verde, elephant tree, mesquite, and creosote bush; endemic to Baja California are the cardon (up to 60 feet [18 metres] in height, a relative of the saguaro) and the unusual boojum tree (known in Mexico as the cirio). Thorn forest occurs in southern Baja and Sonora. Higher elevations support trees adapted to more-temperate climates. Desert bighorn sheep, mule deer, collared peccaries (commonly known as javelinas), mountain lions, gray foxes, and coyotes make their homes in the desert. Other typical residents include desert tortoises, Gila monsters, tarantulas, scorpions, and a variety of lizards and snakes. Rabbits and rodents, such as jackrabbits and kangaroo rats, are abundant, as are several species of bats. Birds include roadrunners, Gila woodpeckers, Gambel’s quail, and a variety of owls and hawks.

Although arid, trees are usually well developed on the desert ranges and their bajadas. Often abundant on these well-drained soils are little-leaf palo verdes, desert ironwoods, catclaw and saguaro. The understory consists of layers of smaller woody shrubs. Tall cholla cactus may occur in an almost bewildering array of species. The alluvial lowlands host communities of desert saltbush, wolfberry and bursage. On coarser soils, creosote bush and bursage communities may stretch for miles. Where the water table is high, honey or velvet mequite may form dense bosques or woodlands. Many species are restricted to alkaline areas.

Stream riparian banks such as the area of Sabino Canyon may be lined with riparian woodlands composed of Arizona ash, Arizona black walnut, Sycamore, Fremont cottonwood and various willows, with a dense understory of arrow-weed, seep willow and carrizo. The

Sajuaro National Park is an excellent representative of the Sonoran, known as the most biologically diverse of the North American deserts, with distinct mountain ranges separated by wide valleys that provide elevational and rainfall diversity. The higher peaks like Mt Lemmon north of Tucson 9,159 feet, (2,791 m), the highest point in the Santa Catalina Mountains include unique woodland assemblages. The lower elevations include large saguaro cactus forest communities that provide excellent habitat for a wide range of wildlife species. The lower

elevation lands also present one of the most structurally complex examples of palo verde/mixed cacti association in the Sonoran Desert. The dense stands of leguminous trees and cacti are dominated by saguaros, palo-verde trees, ironwood, prickly pear, and cholla, and the endangered acuna pineapple cactus. The saguaro is a signature plant of the Sonoran Desert. Individual saguaro plants are indeed magnificent, but a forest of these plants, together with the wide variety of trees, shrubs, and herbaceous plants that make up the forest community, is impressive to behold.

The diverse plant communities present in the monument support a wide variety of wildlife, including the endangered Sonoran pronghorn, a robust population of desert bighorn sheep, and other mammals such as mule deer, javelina, mountain lion, gray fox, and bobcat. Bat species within the monument include the endangered lesser long-nosed bat, the California leaf-nosed bat, and the cave myotis. Over 200 species of birds are found in Sajuaro east and west, including 59 species known to nest, including the elf owl and the western screech owl. The monument also supports a diverse array of reptiles and amphibians, including the Sonoran desert tortoise and the red-backed whiptail.

In summary compared to the Great Basin, Mohave, and Chihuahuan deserts, the Sonoran Desert prominently differs in having mild winters; most of the area rarely experiences frost. About half of the biota is tropical in origin, with life cycles attuned to the brief summer rainy season. The winter rains, when ample, produce huge populations of annuals (which comprise half of the species in our flora).

The Sonoran Desert encompasses 120,000 square miles of the Southwest including Arizona, SE California, Baja Mexico, Nevada and Sinaloa Mexico along the Sea of Cortez

The summer monsoon or rains greatly influences the tremendous plant diversity in the Sonoran. The lighter spring rains bring about flowering of perennials and annuals.

Sabino Canyon and the Santa Catalina Mountains NW of Tucson, with the highest peak Mt Lemmon 9,159 feet

Sabino Canyon in the fall with colors from sycamore and ash.

Rare snowfall on the Santa Catalina Mountains January. Generally the Sonoran Desert is frost free

Sonoran Desert: Left Santa Catalina Mountains, Rt Sajuaro East with Rinkon Mountains, bottom Sajuaro west

Sajuaro National Park West with Sajuaro Cactus and Ochotillo in the forground.

Barrel Cactus species

Fishhook Cactus, Sajuaro Cactus, Cholla Cactus

Fishhook cactus, Opuntia spp, Sajuaro cactus, Ochotilla Bottom: Tarantula, bombardier beetle, Azure blue butterfly

checker spot, painted lady, Danaiid butterfly

Above: hairstreak, Fritillaria spp, swallowtail butterfly; Bottom: buckeye, hairstreak, swallowtail butterfly

Dragonfly, Saturniid moths, Io moth Saturniidae

Red spotted toad, Canyou tree frog, Rt Spadefoot toad that burys itself during dry season and revives in monsoons

Zebra Tail Lizard, Chuquala lizard, Spiny Lizard

Desert Striped Whipsnake, desert tortoise, Collared Lizard

Eastern collared lizard, Kingsnake (rye jones)

Gila, Southwestern Speckled Rattlesnake, Eastern Fence Lizard

Ash-throated flycatcher, lesser goldfinch, pyroluxia, Coopers Hawk, Cardinal overwintering

Costas hummingbird

Mourning Dove nest, Elf owl, Western Screech Owl

Roadrunner, Gila woodpecker on Sajuaro

Cactus wren, Townsends warbler

Cactus wren, ladder-backed woodpecker

Mexican long nosed bat nectar feeding on Sajuaro

Cottontail rabbit, Desert hare, Bottom: coyote

Collared peccary or Javelina, favorite prey of Jaguar that once inhabitated the Sonoran of S Arizona and California

Round tailed groundsquirrel, Desert Bighorn sheep

Mule deer, Bottom: jagarundi captive, coyote