A tropical animal that seems to be extending its range northward, the COATI (or coatimundi) is often seen in the forests of the Rincons. With long snout and long, banded tail, it looks something like an elongated raccoon, to which it too is related. These omnivorous animals travel in bands, rooting among leaves for insects and whatever else they can find.
[Illustration: Desert vegetation near Red Hill, Tucson Mountain Section.]
Natural landscapes may appear unchanging, but this is illusion. Within the apparent constancy, daily and seasonal cycles, fluctuations in numbers, and long-term change are the rule.
Daily cycles are obvious to those who are about at the edges of the day. Take 24 summer hours in the cactus forest of Saguaro National Monument. When the first light comes over the mountains, curve-billed thrashers and cactus wrens sing noisily among the chollas. Other birds soon join in. The early morning walker is likely to hear peccaries grunting in the mesquites along a wash, or see mule deer staring at him, frozen like statues before sudden flight to a sheltering thicket.
At midday, the scene is quiet. Nothing stirs under the baking sun except perhaps a vulture, soaring on the hot air currents. The desert creatures have not gone--they are in the shade of bushes or underground. Even some of the plants are "taking a siesta," having folded their leaves or closed their leaf pores.
Soon after sundown the desert comes to life again. The birds give a subdued version of their morning's vocal performance. Tarantulas begin their slow, stately walk over the ground searching for prey or mates. Coyotes stretch and howl--a prelude to the evening's hunt. As night falls, rattlesnakes emerge from their cool retreats to search out kangaroo rats, which in great numbers are scrutinizing the sand for seeds. And through the night, creatures of many other kinds hunt food to last them through another broiling day.
The rhythmic patterns of the daily cycle are paralleled on a larger scale through the year--seasons of activity follow seasons of quiet. In the desert, rain or lack of rain marks the changes, though gradually rising or falling temperature adds its impact.
The gentle rains of winter prepare the way for the year's greatest burst of activity. By March, spring flowers are blooming and birds are starting to nest. Snakes begin to come out of hibernation. April and May see the apex of spring activity, as insects swarm around the flowering plants, and birds take advantage of this proliferation of food to raise their young. The desert now is yellow with the blossoms of paloverde, mesquite, acacia, and brittlebush.