When southern Arizonans travel during the warmer months of the year, they get looks of sympathy when they reveal their homeplace. "Isn't it hot down there?" "Isn't it hard to live without seasons?" But Sonoran Desert dwellers know they have one up on the questioners, with two distinct seasons during what the rest of the country calls summer.


In Sonoran Desert Summer, John Alcock captures the wonder and the science behind the lives of wood-boring beetles, zebra-tailed lizards, round-tailed ground squirrels, elk owls and saguaro cacti, among other species, during both the desert summers: sizzling, cloudless dry days of May and June, and the intermittent thunderstorms and downpours of the late summer monsoon season.


In his book, hummingbirds vie for the nectar of a flowering saguaro but drop out of aerial combat if the food source isn't rich enough. Gila monsters, orange and black, venture out for brief morning periods from April through June, in pursuit of their diet of birds' eggs and baby quail; the rest of their lives is spent in underground burrows, which explains why they are rarely seen by humans.


Alcock, a zoology professor at Arizona State University, has avoided technical writing. His vivid personal and historical accounts of scientific research play out as mini-mysteries. Sonoran Desert Summer, released in 1990, recently has been published in paperback, as has his earlier book, Sonoran Desert Spring.


The University of Arizona Press, 1230 N. Park Ave., Tucson, AZ 85719. Sonoran Desert Summer: 188 pages. Sonoran Desert Spring: 135 pages. Illustrations by Marilyn Hoff Stewart. Cost of each is $15.95.


* Mary Moran