Sonoran Desert Naturalist

For many of us that live in Rocky Point Mexico we do not know enough about the native vegetation. I found this great article that will help you to understand better the great diversity in our Sonoran desert.

The Sonoran Desert of Southern Arizona and Northwestern Mexico is well known for its beauty and grandly spectacular cacti. The abundant cacti and other succulents defy the harsh climate with exuberant biodiversity. Few realize just how diverse and fascinating are the many other kinds of flora and fauna that also call this area home. The purpose of the The Sonoran Desert Naturalist, is to bring that experience to the Internet visitor, and to encourage all to come and make some discoveries. With an appreciation and love for all that the Sonoran Desert has to offer, hopefully we can safeguard it for our children and their children.

Check out the Desert Wildflower Reports and Nature News featuring current natural events in the Sonoran Desert. In addition to our desert wilderness, The Sonoran Desert Naturalist provides loads of natural history information that can be seen in urban back yards and the city environment. In short, visitors to these pages experience the sights, sounds, smells (in words!), and textures of the Sonoran Desert. Come back often to see what's new!

What is a Desert? For many people the concept of a desert means hot temperatures together with a profound shortage of water. There are, however, deserts that are cold for much if not all of the year. The Great Basin Desert in the United States and the Gobi Desert in Asia for example have bitterly cold winter seasons yet present the sparse vegetation and dry soils typical of deserts. In Central Florida, where rainfall exceeds 1500 mm/year, there are sand hills that become very dry only days after rain because the water leaches out of the root zones very quickly. There are spiny cacti, drought tolerant shrubs together with birds and reptiles typical of "real" deserts. In the canopies of tropical American rain forests the tree branches themselves support epiphytic plants ("air plants") including cacti and bromeliads that very much resemble desert plants. Tree canopies are sunny and hot while gravity ensures that despite abundant rainfall, water is nearly always in short supply. Within the boundaries of well recognized deserts there are wet places such as oases and river banks. Most authorities recognize a desert as a place that receives less than 300 mm of rain each year and where the evaporation rate exceeds the precipitation rate for the greater part of the year.

What and Where is the Sonoran Desert? The idea of a desert for many people conjures an image of shifting sand dunes or barren rocks devoid of vegetation and obvious animal life or habitation. Such areas do exist within the Sonoran Desert but for the most part this is a lush desert that receives 120 to 300 mm of precipitation each year. This is also a hot desert with daytime temperatures reaching or exceeding 40° C for much of the summer season, May to September, while hard freezes are uncommon during the mild winters. A very unique feature of the Sonoran Desert is that the rain arrives during two wet seasons, one generally December through March, the other July through Sept. The lack of hard freezes and moisture distributed through the year has promoted the abundance of succulents that can store water for later use. The area generally recognized as the Sonoran Desert includes the southwestern third of Arizona, a small area of southeastern California, most of Baja California del Norte and the western half of Sonora, Mexico.

Climate and vegetation types within the Sonoran Desert vary considerably across the region and with elevation in the many mountain ranges. In general, the amount and predictability of winter rainfall is higher in the west and lowest in the southeast. Summer wet season is more generous and lengthy in the southeast and shortest to the west. As one proceeds south within the Sonoran Desert the winter season is less severe, where more subtropical and tropical elements appear. Upland Sonoran Desert (orange on map) occurs in southwestern Arizona and is characterized by a balanced distribution of winter vs. summer rainfall. Winter frosts are common, but not severe. Succulent cacti, highly drought tolerant shrubs, and thorny shrubs are equally common. Towards the north, especially on mountain slopes, the vegetation merges towards chaparral type vegetation which is characterized by dense thickets of evergreen shrubs that are also fire adapted. Then towards the northwest the Sonoran merges with the Mohave Desert where summer rainfall is usually scarce. The driest and hottest region is the Colorado Desert (yellow on map) located in the lower Colorado River valley. Annual rainfall can be less than 50 mm while summer temperatures commonly approach 50° C. Areas of sand dunes occur in this area, and the Gran Desierto, located in Mexico to the east of the Colorado River presents the most inhospitable (yet also beautiful) terrain. Vegetation consists mostly of highly drought tolerant shrubs with few succulent cacti. The Sonoran Desert in Sonora, Mexico has a longer, wetter summer rainy season with a drier winter (brown on map). Drought deciduous trees and shrubs become increasingly common towards the south, many of which are quite thorny. Succulent cacti are abundant and diverse. The Sonoran Desert rather gradually merges into the more southerly Tropical Dry Thorn Forest of Southern Sonora and Sinaloa. The Sonoran Desert on Baja California is often referred to as the Vizcaino Desert (red on map). Cool moist weather comes in winter, the summers are not quite as hot due to the cooling effect of the Pacific Ocean, and occasionally summer brings good amounts of rainfall. Moisture from fog and dew can be considerable in some locations allowing epiphytes (air plants) to grow suspended from typical desert plants such as the ocotillo. Succulents including cacti, agaves and yuccas are abundant and extraordinarily diverse. The characteristic Boojum Tree plays as a succulent and a drought deciduous tree at the same time.

There's so much more to experience and learn!
Visit every page of the Sonoran Desert Naturalist:

Back Yard Naturalist, Phoenix, Arizona -- Here I describe the many goings on that often go unnoticed in any urban landscape. Focus is especially on the plants and the insects that live on them, but also birds and reptiles. There are fascinating stories about aphids, bees, ants, cicadas, whiteflies, katydids, and butterflies. Find advice on how to make your yard wildlife friendly.

Flora and Fauna News, Sonoran Desert Edition -- This page is designed to give a newspaper-like account of natural events that take place in the desert as well as in the Phoenix and Tucson urban habitats. By browsing through past issues the seasonal progression can be experienced.

Desert Places -- This index page has numerous links to maps and descriptions of accessible trails, parks, canyons, mountains, and wild places that offer desert experiences. The natural history of Phoenix Mountains Preserves are described in detail. If you are intested in joining or organizing field trips to experience the Sonoran Desert then consider joining Arizona Natural History Field Trips.

Field Guide -- This page has links to all the flora and fauna pictures as well as many, many species descriptions including Butterflies, Spiders, Beetles, Bugs and Grasshoppers.

Common Birds: Desert, Riparian & Wetland and City

Plant Families -- Sonoran Desert Flora arranged by family classification.

Links -- An extensive and ever expanding list of web sites that offer information on exploring nature in the Sonoran Desert.

Urban Habitats, Metropolitan Phoenix, Arizona -- Grenada Park, canals across the city, gardens and ponds, and a bat colony are examples of easily accessable nature experiences for city dwellers. The nature lover can make valuable observations of dragonflies and other aquatic insects. There are the usual urban birds inhabiting the parks as well as feral and released water fowl.

Desert Wildflower Report Spring 2009

March 28^th & 29^th, 2009. The wildflower season on the low deserts is definately on the wane. Without significant rain since early February the annuals have mostly dried up. Steve G. found some interesting things in the sand dunes near Yuma, but he had to search carefully. At Dreamy Draw in Phoenix, Arizona the annuals have finished blooming, but good shows of perennials and cacti are on. At the Estrella Mountains the soil is very dry now and again blooming is restricted mostly to perennials and cacti. Buckhorn Cholla and Engelmann Hedgehog were especially colorful.

March 14^th & 15^th, 2009. On Saturday I hiked South Mountain Park in Phoenix and found that annual wildflowers are mostly well past their peak and mostly going to seed. Most kinds can still be found in shady, protected spots. Cass Blodget found some poppies, but I did not. Perennial shrubs on the other hand are blooming nicely and some of the first brilliant hedgehog cactus have open blooms. Brittle Bush, Golden Eye, Trixis and Fagonia are just some of the many colorful blooming shrubs. Then on Sunday I hiked northeast of Carefree, Arizona and found that despite dry conditions great shows of poppies, phacelias and lupines are present especially in areas burned by the Cave Creek Complex fire. This is one of the ironies of range fires is that the habitat often returns with exuberant abundance and color. Areas along the Seven Springs Road and the Bartlet Dam Road were fully in bloom. This area is generall described on the web page for Rackensack Canyon.

March 8^th, 2009. The Apache Trail out northeast of Mesa, Arizona was ablaze with color: Bright green shrubs; orange, red and yellow lichen-encrusted boulders; towering cliffs of volcanic tuff; and lots of wildflowers. Tops among them were Brittle Bush, bright yellow daisies lining the roadway. Also seen blooming were bluedicks, bladderpods, fiddlenecks, popcorn flower, jojoba, blue fiesta flower and bursages. (Bursages have greenish flowers and go mostly unnoticed, but may be you source of hay fever allergins. If you know you are succeptable you can take anti-allergy meds before your trip). The colors will last weeks more in this area as a succession of trees, shrubs and cacti come into bloom.

March 1^st, 2009. The low deserts of western Arizona are at peak blooming now. Brittle Bush blazes brightly along the edges of the Interstate highways and paved roads. On the slopes and flats 1000's of annuals just a few centimeters tall cover every square meter. This is not a banner year in the low deserts, but there is planty to see and explore for the hiker and photographer. With temperatures expected to surpase 32° C the next few days those annuals will go to seed and brown rapidly. The perennials like brittle bush and cacti will continue to please for a month or more. Higher elevations to the east and north of Phoenix and Tucson should be great for wildflowers the next two months.

Feb. 23^th, 2009. Temperatures this week will be much above average in the Sonoran Desert surpassing 30°C in most locations below 1000m elev. As a result flowers will begin blooming and the available moisture will be used at an increasing rate. Many things in the lower elevations are already blooming, but spectacular shows are not yet evident. Many of the annuals seen this past weekend appear small by comparison, so blooms will be fewer and less spectacular. At Pima Canyon near Tucson I found some of the earlier species blooming such as brittlebush, bursage, mustards, fiddlenecks, jojoba, Pholisoma and pellitory.

Feb. 10^th, 2009. A series of storm systems with significant moisture began moving into the Sonoran Desert Feb. 6^th. This rainfall has been widespread, thus most areas will soon have excellent shows of wildflowers. Rainfall overnight, Feb. 9 thru 10, was heaviest north and east of the Phoenix area. The lowest, warmest areas already have a few diminutive flowers blooming. By early March or even late February many areas will be blooming nicely; depending on elevation blooms should be good through April. If the rain continues we may even have areas with 'banner year' shows.

Following several significant precipitation events in the Sonoran Desert during November and December the month of January was almost entirely dry. Two Pacific storm systems in the closing days of January yielded only minimal rainfall. With mild temperatures the desert mountains greened up significantly, primarily due to the shrubs Triangle-leaf Bursage (Ambrosia deltoidea) and Brittlebush (Encelia farinosa). On the soil surface in many areas diminutive annuals having germinated earlier stood a few centimers tall. Check back here for further updates.