The so-called "Aztec ruin", which is situated on the banks of the Animas River in northwestern New Mexico, substantiates this hypothesis of the voluntary desertion of the cliff dwellings. In this ruin is found unmistakable evidence of a secondary occupation which has been definitely identified as a Mesa Verde settlement. It is thought that certain of the present-day Pueblo Indians are descendants, in part at least, of the cliff dwellers. Many of these Indian towns or pueblos still survive in the States of New Mexico and Arizona, the least modified of which are the villages of the Hopi, situated not far from the Grand Canyon National Park. FAUNA AND FLORA The fauna and flora of Mesa Verde should be particularly interesting to visitors. A combination of desert types from the lower arid country and mountain types, usually associated with regions of greater rainfall, occur here. The desert types are highly specialized to cope with their environment, particularly the plant and smaller animal life. Rocky Mountain mule deer are perhaps the only big game to be found abundantly in the park. They are often seen. Their numbers in the park, however, vary greatly according to the season. It is hoped to reintroduce the native species of Rocky Mountain bighorn as soon as range sufficient for the needs of this species has been added to the park. Occasionally a black bear is reported. Cougars, or mountain lions, and bobcats are part of the wildlife of the park and, strange to say, are occasionally seen in broad daylight. In other national parks these animals are rarely seen even by rangers. Coyotes and foxes are not as numerous as they once were on the mesa. As a result of the reduction of the predators, many of the smaller animals, such as rabbits, porcupines, and prairie dogs, have greatly increased. Rock and ground squirrels and the Colorado chipmunk are present in great numbers. More than 200 varieties of birds have been recorded. The species range from the majestic golden eagle, the largest bird, down to a variety of dainty humming birds. Game birds are represented by the dusky grouse. No wild turkeys are now to be found in the park, although it is believed that they were once here. The cliff dwellers domesticated the turkey, and their bones, feathers, and droppings are found in all the ruins. At present the reintroduction of wild turkeys to Mesa Verde is under consideration. [Illustration: A YUCCA PLANT IN FRUIT (YUCCA BACCATA)] Among the interesting animal residents of Mesa Verde are the reptiles. The lizards are represented by the horned lizard, the western spotted or earless lizard, the collared lizard, the striped race runner, utas, rock swifts, and sagebrush swifts. Among the snakes are found the bull snake, the smooth green snake, the western striped racer, the rock snake, and the prairie rattlesnake. The latter, the only poisonous species on the Mesa Verde, lives among the rocks in the lower canyons.