[Illustration: Photographer Galen Rowell and writer Dennis Hanson decided to climb the Tower in October 1978 to find out for themselves what’s up there. After a strenuous five-hour climb, interrupted by occasional clouds of rock doves (below), they reached the top and found the surface is not as flat as it appears from down below or even from an airplane. Besides grasses, they found sagebrush, currant, and prickly pear cactus (below). As they were cooking dinner, a wood rat (below) joined them, nibbling at their food packets, peering into a pot, and nosing about their climbing gear. They also saw chipmunks and plenty of birds (See pages 44-45, 60-61), but, perhaps because of the coolness of October, they did not see any rattlesnakes, which others have found there sometimes. How did the animals get to the top? Some people have speculated that they were dropped by predatory birds, but that is questionable: they probably would have been killed by the birds’ talons or by the plunge to the surface. More than likely they just climbed up the Tower’s sides and took up residence. Many climbers, of the human sort, have reported seeing snakes and rodents working their way up fissures.] [Illustration: What’s on top of the Tower? Most climbers report that the summit is similar to the surrounding landscape. Grasses cover much of the rocky surface, but better than that, a few snakes and mammals live there!] [Illustration: Wood rat.] [Illustration: Prickly pear cactus.] [Illustration: Rock doves.] In addition, most plains animals contend with the semi-arid conditions of their environment by making efficient use of available moisture. Pronghorn, prairie dogs, and kangaroo rats, for example, need never take a drink since they obtain necessary water from the plants they eat. Such plant and animal adaptations explain why the shortgrass plains can sustain such a vast panorama of life. From a tall pine upslope, a red squirrel chatters with indignation at discovering my intrusion into its domain. The bell-like song of a rock wren answers from an outcrop nearby. The small gray bird appears atop a boulder, motionless but for an instant, then hops down to resume its search for insects among the bright, arid cliffs it claims for its own. I realize that I am seeing more than scenery here. All around me are boundaries—conspicuous where defined by plants, but invisible where respected by animals. No prairie dog has ever traveled across this slope, and no red squirrel has ever scurried into the treeless expanse of the prairie dog town. On no occasion would a rock wren enter the deep pine forest. Should its food supply somehow vanish, it would perish among the bare earth and gully washes of its own habitat rather than hunt the dog town or forest floor.