When the Rains Come

A Naturalist's Year in the Sonoran Desert
John Alcock


I have been fortunate to live in Arizona's Sonoran Desert for more than three decades. During this time, I have gone out again and again to certain desert locales, several of them not much more than a half hour's drive from my home in Tempe, a suburb of Phoenix. I have become especially familiar with one place in particular, the Usery Mountains, a perfectly ordinary, but utterly wonderful, collection of hills that are home to an assortment of desert insects. As an entomologist of sorts, I owe a lot to those insects, and this book gives me an opportunity to share my enthusiasm for them and for the equally interesting plants that are found in the Userys and in some other attractive parcels of desert that I have also visited repeatedly over the years.

By taking my camera with me when I travel to my favorite desert spots, I have been able to photograph certain objects and landscapes on many occasions. Although the desert looks pretty static at first, second, or even third glance, my photographs taught me that this is an illusion, even in areas untouched by urban sprawl and off-road vehicles. True, most desert plants grow very slowly, but grow they do, and in the process they change the desert around them. These changes are in turn superimposed on others that occur regularly on a seasonal basis. Indeed, despite the fact that some people think that the subtropical deserts of the Southwest are immune to the seasonal distinctions so characteristic of north temperate zones, the seasons of southern Arizona are real and full of significance for an appreciation of the place. Indeed, most naturalists accept the claim that the Sonoran Desert actually has more seasons (five, not four) than most places. So in central Arizona, spring (mid- February to April) is followed by the arid foresummer (May and June); then the monsoon summer (July to September) is capped by a twomonth fall (October and November), topped off by winter (December to mid-February). In keeping with the importance of seasonal changes in the Sonoran Desert, I have structured this book about my experienc es in the Userys and other nearby sites chronologically, over the course of one year, January to December 2006.

Many of the gradual changes that take place in the desert because of the shifting of the seasons would occur whether or not we humans were present. As such, they can be considered "natural" and therefore (perhaps) desirable and attractive, or at least not upsetting. The same claim is not usually made for most of the changes imposed on the desert by human beings and their livestock, their farms, and their cities. These changes do distress those of us who value any area with even a residual hint of the pristine.

Admittedly, remarkably few places in the entire world qualify as wilderness, if we apply that term only to areas that are truly free from human influence, a conclusion reached by a bevy of conservation biologists led by Eric Sanderson. His research team mapped the human "footprint" on the planet by using satellite pictures and the like to produce scores for such things as population density per hectare (one hectare equals about 2.5 acres), the degree of habitat transformation, the presence of roads, and the availability of electrical power. They then summed the scores, distributed them over the Earth's land surface, and then categorized all the regions of the world in terms of human influence, from very low to very high. Needless to say, the lowest- scoring regions were places like Greenland, the high arctic, and the Sahara, while the highest-scoring sites were the world's large cities: New York, Tokyo, London, and so on. But perhaps the most interesting and sobering figure is that not just cities, but more than 80 percent of all terrestrial surface of the planet can be classified as nonwilderness because the place contains one or more persons per hectare, or is being put to use by agriculturalists, or lies no more than fifteen kilometers (nine miles) from a road, major river, or coastline (insuring easy access by people), or has artificial lights that can be picked up at night by a satellite (74).

I do not know what percentage of Arizona is free from the human footprint, but I bet that the percentage is low. People have been in Arizona for at least twelve thousand years, and currently there are more than five million of us, primarily in that part of the state where the Sonoran Desert once ruled supreme. Our species has generated all sorts of changes here over the past twelve thousand years, but especially over the last century. No book about our desert could therefore sensibly avoid an examination of how humans have altered where we live. Whether we like it or not, we are the major player in the desert now, a heavy-handed and heavy-footed player certainly, and what we have done here is therefore part of the story. Becoming aware of the entire spectrum of changes in our desert may give us a better sense of where we live and a greater appreciation for it. I would like to think that it is all worth knowing about, from the activities of a desert wasp to the rhythm of a desert year, from the establishment of a tiny saguaro to the death of a mature saguaro a century and a half later, from the deposition of a potsherd in the desert in 1430 to the re-creation of a desert wetland nearly six centuries later. One thing is certain: we do not live in a wasteland. Far from it. We Arizonans occupy a land with a glorious history, both natural and unnatural, a rocky, spartan, often bone-dry desert that happens to be one of the richest deserts in the world biologically speaking, a desert that still has the feeling of wilderness about it, even in mountains within sight of Greater Phoenix. For this I am grateful, even during a drought when the paloverdes, the desert insects, and I are anxiously waiting for rain.

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