In his Chasing Monarchs travelogue, Pyle starts by the Similkameen River in Canada, traveling south along the Columbia and Snake rivers, through the Great Basin, up onto the Colorado Plateau and into Mexico before swinging up to the California Coast.
Along the way, he delivers delightful riffs on the butterfly. He explains how the insect adjusts its center of gravity for optimal gliding by taking on or expelling water for ballast. He finds monarchs easily travel thousands of miles in a few days, and confirms the theory that Western varieties do not all winter in California - some split off into Mexico.
Pyle's compact, evocative descriptions make you want to grab an atlas, jump in a car and hit the road. Of Utah's Black Rock Desert, he says, "It was black pumice and pudding pahoehoe, lava that looked a lot like dark-chocolate fudge abandoned in midswirl."
Peopling the landscape are river guides, border patrolmen, waitresses, Native Americans and writers who know the monarchs' whereabouts and their local habits. Monarchs, Pyle discovered, cross mountain ranges at will, and over-winter where they choose. But the rapid spread of development and the proliferation of herbicides make him fear for their future.
Chasing Monarchs: Migrating with the Butterflies of Passage, by Robert Michael Pyle, Houghton Mifflin Co., 215 Park Ave. South, New York, NY 10003. 289 pages, $24.