Part 5

Except for small lizards, reptiles are not much in evidence in the monument. Nevertheless, they are present and are important in the various plant-and-animal communities in which they live. Almost all lizards are insectivorous, and along with birds and other insect-eaters help to keep the number of insects within bounds. A notable exception is the GILA (HEE-lah) MONSTER, (See appendix for scientific names of reptiles) largest of the lizards found in the United States. (It is one of the world’s two poisonous lizards, and the only one found in this country.) The gila monster is especially fond of bird eggs, and also eats nestlings and small rodents, obtaining necessary moisture from their body juices. These food habits are quite similar to those of the several species of snakes found in the monument, the majority of which are perfectly harmless to humans.

Just as the lizards help to control the insect population, the snakes are important in preventing the buildup of large numbers of rodents that would result in widespread damage to vegetation. Visitors to the monument rarely have the opportunity to observe snakes, since they are in hibernation during winter and remain in the shade or in underground burrows during the hot part of each summer day. Perhaps those most frequently seen are the GOPHER SNAKE and the COACHWHIP. Many desert snakes hunt only at night; others that are normally active during days of moderate temperatures become night hunters during hot weather. Although they are not abundant, there are several kinds of rattlesnakes in the monument, the commonest desert species being the WESTERN DIAMONDBACK and MOHAVE RATTLESNAKES. Except for the small, very rare, and secretive ARIZONA CORAL SNAKE, rattlesnakes are the only poisonous snakes in the monument. Snakes, like other living things in the national monument, are protected by law.

Don’t be surprised while following a desert footpath to come upon a plodding tortoise. This bona fide desert dweller, the DESERT TORTOISE, is a vegetarian, feeding on cactus, grass, and other low-growing plants.

Birds

Because of its great variety of habitats, ranging from luxurious desert vegetation to deep mountain forests, Saguaro National Monument provides food and shelter for many species of birds. Some of these reside all year within a single zone, while others move upward in summer, returning to the desert when the mountaintops are covered with snow. Other species pass through the monument in spring and autumn in their annual migrations between Latin America and summer nesting grounds in northern United States or Canada. The following species are those you are most likely to see.

A common year-round desert resident is the CURVE-BILLED THRASHER, noticeable, noisy, and about the size of a robin. These energetic inhabitants of the cactus forests nest in mesquite clumps and cholla thickets. Their diet—they feed on insects and succulent fruits—makes them comparatively independent of water. The thrashers are delightful songsters. The CACTUS WREN, looking somewhat like a small thrasher, is even noisier. It protects its nest by building in a cactus. This wren lives largely on a diet of insects, but about 17 percent of its food is seeds and fruits. One of the most attractive of the ground birds is the GAMBEL’S QUAIL. Many coveys are found throughout the desert within close range of water. In winter, Gambel’s quail feed mainly on seeds, berries, and plant shoots; in summer they augment this diet with ants, grasshoppers, and other insects. The ROADRUNNER, ungainly clown of the desert, is frequently seen by visitors as it scuttles through the underbrush along the margins of sandy washes. Not particular as to food, it is sometimes seen with the tail of a lizard protruding from its beak, and it is known to eat insects and spiders, snakes, young rodents, small birds, seeds, and fruits. Quite capable of flight, the roadrunner prefers to trust to its legs and the security of thickets, but will take to its wings if pursued in the open.

Two members of the woodpecker family closely associated with the saguaro cactus are the GILA WOODPECKER and GILDED FLICKER. Called carpenter birds because they drill nest holes or pockets in the saguaro stems, both species are of particular interest because of their limited range and specialized habitat. Two other desert birds, sufficiently similar to be confused, are the red, black-faced CARDINAL and the gray-and-red PYRRHULOXIA, both of which have crests. Look for these species in the shrubs along washes. Several kinds of doves are found in the desert, including the common MOURNING DOVE and the WHITE-WINGED DOVE. Mourning doves are all-year residents, while the large white-wings drift in from Mexico in May, remaining long enough to raise families and join other animals in harvesting fruits of the saguaro.

Seen and heard in the desert all year, the canary-voiced HOUSE FINCH raises its family among cholla and mesquite thickets. The tinkling song of the ROCK WREN is a familiar sound in the desert in winter. These gray ground dwellers go farther north or to higher elevations to nest.

The PHAINOPEPLA is one of the most noticeable of the desert birds because of its silky crest, glossy black plumage, and habit of perching on the topmost branch of a tree while indulging in flutelike song. A permanent resident of the monument, subsisting on mistletoe berries and other vegetable matter in winter, it has a diet of insects, principally ants, during the rest of the year. Flycatchers are especially abundant and conspicuous during spring and early summer when the blossoms of trees, shrubs, and the larger cactuses attract swarms of insects. Among these birds are SAY’S PHOEBE and ASH-THROATED FLYCATCHER. The LESSER NIGHTHAWK lives on a diet of insects, which it catches while on the wing. It is especially noticeable from May to September as it skims the tops of the tallest saguaros in the dusk of evening. The lesser nighthawk also ranges up to the oak woodlands.

Predators are an integral part of the bird population, one of the smallest and most active being the LOGGERHEAD SHRIKE. This black-and-gray bird gorges itself on beetles and grasshoppers when insects are abundant, turning to lizards, rodents, and small birds at other times. It has the unusual habit of impaling its prey on thorns for future use. The RED-TAILED HAWK is the commonest of the large soaring hawks, which live mainly on rodents and reptiles. It builds its large stick nest in the forks of saguaro arms. Like the shrike and the SPARROW HAWK, the red-tailed hawk is found in grasslands, chaparral, and woodlands as well as in the desert. Because of their nocturnal habits, owls are not often seen by visitors, but they are abundant in the monument. In addition to the GREAT HORNED OWL, which like the red-tailed hawk feeds principally on rodents and builds cumbersome nests in saguaro branches, the SCREECH OWL and the tiny ELF OWL are numerous in the cactus community. Screech and elf owls make use of abandoned woodpecker holes in saguaros, not so much for nesting as for dark and comfortable hiding places during daylight hours; they emerge after sunset to hunt insects and small rodents. Best known of the carrion eaters, the TURKEY VULTURE is rarely seen on the ground, but is a common sight, singly or in groups, circling high in the sky.

The oak-pine-juniper woodland has its set of birds too. One of the noisiest, most quarrelsome, and most mischievous is the MEXICAN JAY, a permanent resident. In summer, it shares this habitat with the night-flying poor-will, which closely resembles the nighthawk but lacks the white wing patches. Shy, secretive, and protectively colored, this bird is rarely seen, but its plaintive call is a familiar twilight sound at the middle elevations of the mountains. Here, too, is found the strikingly patterned HARLEQUIN QUAIL, which waits until you are almost upon it before flushing. The _RUFOUS-SIDED TOWHEE_ prefers brushy slopes and canyons, where it trills its monotonous song from the branch of a skunkbush or scratches noisily and industriously among the fallen leaves beneath an oak. And anywhere from the oak-pine woodland to the top of the Rincons, you are likely to startle the large BAND-TAILED PIGEON from its perch.

The pine and fir forests of the higher Rincons are rich in bird life in summer, but only a few species remain the year around. Among the latter is the STELLER’S JAY, which includes insects in its summer diet but feeds mainly on acorns and other vegetable material in winter. The MOUNTAIN CHICKADEE is busy among the branches of the large pines and firs even when snow lies deep on the ground. PIGMY NUTHATCHES—tiny, constantly twittering insect-eaters—also remain all year.

In summer, when insects are plentiful, the mountain forests are alive with birds. The MEXICAN JUNCO, which winters at lower elevations, hides its nest in grass clumps among the firs and aspens. Hummingbirds of several species pause on vibrating wings to suck nectar from blossoms in the meadow at Manning Camp. Brightly colored summer visitors such as the HEPATIC TANAGER and the PAINTED REDSTART search for insects among the pine boughs or flash in the sunlight as they flutter across open glades in the forest. The mountaintops, too, have their predators; the COOPER’S HAWK, which nests in wooded canyons, is large enough to lift a pigeon or rabbit, but generally preys on rodents and smaller birds. The largest bird known to inhabit the Rincon Mountains is the TURKEY, which nests and raises its young among the firs and aspens. It descends in winter to the oak-pine woodlands, where it feeds on pinyon nuts, acorns, and grass seeds.

Mammals

The most frequently seen mammals in the monument are rodents and members of the hare clan. Among the latter group are two rabbits. The DESERT COTTONTAIL is common in the lower levels of the desert, and the EASTERN COTTONTAIL inhabits the mountains to 8,600 feet. Adaptable to a wide range of environmental conditions, these animals augment the water they obtain from springs with moisture derived from sap. There are two species of JACKRABBITS (actually hares) in the monument. They remain at the lower levels, where they are a common sight amid the cactuses. Unlike rabbits, which are born naked, blind, and helpless, hares are born with fur, open eyes, and the ability to move about.

Among the monument rodents the largest are the PORCUPINES. Though rarely seen, they leave characteristic scars on pinyons and ponderosa pines, recording their feeding habits at higher elevations. They are also active in the chaparral belt, and an individual occasionally wanders down into the desert where it eats mesquite beans and samples the bark of ocotillos and other shrubs and trees.

Several species of ground squirrels are abundant. At the lower levels, especially among creosotebushes, the ROUNDTAIL GROUND SQUIRREL finds suitable living conditions, while the YUMA ANTELOPE GROUND SQUIRREL ranges from the cactus forests into grassland. At this elevation and upward through the pinyons and junipers, the ROCK SQUIRREL makes its burrows in rocky ledges and brushy canyons. CLIFF CHIPMUNKS enliven the oak-pine woodland and higher forests with their quick movements and cheerful chatter.

KANGAROO RATS honeycomb the soil from the cactus forests up to the oak-pine belt. Remaining underground during the day, they are frequently seen at night. These animals do not require free water; they obtain adequate moisture from a chemical process within the body during the digestion of food, which is mostly dry seeds. WOODRATS, famous in song and story as pack rats or trade rats because of their habit of carrying away objects of human use and leaving something else in their place, are found throughout the monument at all elevations. Look for their stick nests among the pads of prickly pear, a favorite food.

Other rodents common in the monument include the CACTUS MOUSE, GRASSHOPPER MOUSE, DEER MOUSE, and VALLEY POCKET GOPHER.

Among the larger mammals in the monument are two species of deer. The MULE DEER subsists in winter on cactus fruits, ephemerals, and other desert vegetation. In summer they find abundant browse in the higher oak woodland. The forested areas along the crest of the Rincons support a population of the smaller WHITETAIL DEER. These graceful animals browse on aspen, buckbrush, and other shrubs and small trees. They are particularly fond of acorns. When snow flies some descend to the protective cover of the oak-pine woodlands and chaparral.

PECCARIES, characteristic of southwestern deserts, usually travel in herds of from three to as many as 50 animals. They wander through the groves of mesquite along desert washes, and root among beds of pricklypear. Pricklypear pads are their chief food; they are said to feed upon cactus fruits in summer and autumn. In addition to the moisture obtained from succulent stems and fruits, peccaries require considerable water, hence they frequent springs and seeps. Small bands of these animals occasionally visit the waterhole near the visitor center, where they are excitedly watched by visitors fortunate enough to be in the lobby at the time.

Saguaro National Monument also has a large number of predatory animals. Many of these, popularly believed to be exclusively meat-eaters, actually also eat much vegetable matter. The predators—an exciting part of the monument’s fauna—play an important role in preventing overpopulation of the prolific rodents.

Chief among predators is the COYOTE, which ranges throughout the monument. In winter, coyotes are found principally below 6,000 feet, where hunting is easier and where rodents remain longer out of hibernation. They are also known to roam the forested heights of the Rincons and Tanque Verde Ridge. Studies of coyotes in the monument made by biologist Lowell Sumner in January 1951 showed that their winter diet consisted of about 78 percent fruits and seeds, 11 percent small rodents, 7 percent deer, 4 percent birds, reptiles, insects, and carrion, and 1 percent debris. The coyote is one of the principal wild creatures associated with the history of the West, and its continuing presence in the monument brings a thrill of pleasure to visitors who hear the voices of the pack during the calm of evening, or catch a glimpse of one of these gray canines trotting through open stands of saguaros. BOBCATS, ranging over much the same territory as coyotes, subsist principally on rodents, birds, and insects. Because of their secretive habits, they are seldom seen.

The GRAY FOX is another fairly common inhabitant of the cactus desert and higher brushlands, and is also known to roam the forested uplands. It is usually seen at night. Rodents are its principal source of food, but it also preys on birds and reptiles and eats much vegetable matter. The smaller and rather rare KIT FOX, restricted mostly to the desert, is also a night hunter. Kangaroo rats are a favorite item in the kit fox diet, but these small predators also eat grasshoppers and other insects.

Skunks, members of the weasel family, are relatively common in the monument, and several species inhabit areas where water is available. They are usually active at night. The HOGNOSE SKUNK is a desert dweller recognizable by its solid-white back. It roots for insect larvae and eats cactus fruits, bird eggs, and nestlings. The STRIPED SKUNK ranges throughout the monument; the SPOTTED SKUNK is found at all elevations, usually among rocks. Insects, rodents, and fruits are its main food.

Another member of the weasel family, the BADGER, is occasionally seen in the desert although it is by no means limited to that habitat. The badger feeds mainly on rodents, which it digs from burrows with its strong forelegs and heavy claws.

The RACCOON, longer-legged than the badger, is readily recognized by its gray fur, black mask, and ambling gait. It inhabits brushy canyons having permanent water, and sometimes wanders up into the pine belt in summer. Amphibians, scarce as they are, and other water creatures are among the preferred foods of raccoons; but they also eat small rodents and plant food, including berries, acorns, and other fruits.

The RINGTAIL, a smaller relative of the raccoon, is somewhat similar in habitat preference and nocturnal habits. Its flattened, bushy tail, acting as a balancer, helps this short-legged, agile animal in leaping from point to point on the steep rocky surfaces it seems to favor. It sometimes takes up residence in little-used or abandoned buildings, where small rodents, its principal source of food, are usually abundant. About the size of a house cat, it has large eyes and ears and alternating dark and light bands on its tail.

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.

the rhythms of nature

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.

But April also marks the beginning of a drought that intensifies through May and June, making these last 2 months the year’s parching crucible in which reproductive ability is tested. If winter rains have been meager, the heat and drought of May and June can kill all the young of many birds. Some birds, such as Gambel’s quail, may not even attempt to nest in a dry year. Conditions may be so harsh at this season that some mammals, such as the pocket mouse, close up shop completely, sleeping the days away underground.

Relief comes with the rains of July and August. Now the summer annuals spring magically from the ground, perennials put forth new leaves, and saguaros do all their growing for the year. This summer burst of plant growth is accompanied by a new hatching of insects, which allows a few more birds to nest, and along with the new vegetation supports a larger pyramid of animal life generally. Among the new animals that reappear are toads, which now emerge from their long sleep in the soil to mate and lay eggs in the pools formed by summer rains.

When the last torrential rain of August or September falls, a new dip in the yearly cycle of activity begins. This one is not so deep, not so trying, as the drought of early summer, but it too is a time of relative quiet. Roundtail squirrels go underground to sleep until cooler weather comes. Now the migrating birds slip through, hardly noticed among the mesquites and paloverdes. Butterflies lay their eggs, in preparation for a new generation beyond the winter. Signaling the last phase in the yearly cycle, wet canyons turn yellow and brown as cottonwoods, willows, and sycamores present a pale version of the spectacular foliage displays seen in the East.

While these daily and seasonal cycles are following their well-known courses, each species of plant and animal is undergoing its own fluctuations, in a constant struggle that generally goes unnoticed. For the balance of nature is not a static one, but more like the rocking of a seesaw on its fulcrum. The population of a species goes up one year, down another—depending on the weather, the food supply, predators, competitors, and a thousand interactions that reverberate through the community in which it lives. The numbers of some species, like the Gambel’s quail, fluctuate wildly from year to year, while those of others, such as the harvester ant, remain quite stable. But the oscillations of the seesaw, big and little, average out from year to year so that the species maintains itself in the community. The other members are going through the same thing, in a system of checks and balances that over the short run keeps the whole community nearly constant.