If you stand at the overlook, you will see the Green River, Split Mountain, and a rolling plain to the south that stretches to a hazy line of mountains. To many, it is an unfamiliar land that lies strangely subdued beneath a blazing sun and an intensely blue sky.
That blue sky is the key to the kinds of plants and animals that live in this part of the monument. They live most of their lives under blue sky, and, even when clouds do form over the mountains and drift across the lowlands, the results are disappointing. A high wind, dust and sand, a few drops of rain, and the storm is over.
The climatic conditions under which local plants and animals live are conditions of extremes. On summer days the temperatures may rise above 100° although the nights are usually cool. During the winter, temperatures may skid to 30° below zero or more. It is not uncommon for the thermometer to remain below zero for weeks on end. But the most influential climatic factor is waterand there is little of it. The total yearly precipitation is a little less than 8 inches! It is interesting then to find such a wide variety of plants and animals that not only survive but flourish under such rigorous conditions.
The methods used by plants in adapting to arid conditions are interesting and varied. The wide-spreading, shallow root system and thick stem of the cactus enhance collection and storage of water. These strange plants are quite plump with stored water in the spring when the snows melt, but they gradually lose this plumpness during the dry summer, and by autumn many seem lifeless.
Other plants conserve their water by minimizing the loss through their leaves. This may be done in a number of ways. The leaves of the spiny greasewood are covered with a waxy substance that inhibits water loss while the leaves of the sagebrush are covered with hairs or fuzz that serve the same function. The leaves of the juniper are scale-like and really don't look like leaves at all. The most direct method of preventing water loss through leaves is to drop the leaves themselves, and this method is used to a greater or lesser degree by many desert plants. The serviceberry is a good example of this method. In late summer it looks dead, and yet the following spring finds it robed in green and covered with flowers.
In contrast to the frugal habits of the plants just described, the cottonwoods seem lavish indeed. Usually big trees, they spread a canopy of green in whose shade rest birds and animals alike. Have you ever rested under a cottonwood? If so, you will remember it as being cool even on the hottest days. Part of the coolness was due to the hundreds of gallons of water which are transpired through the leaves each day. Because cottonwoods require so much water, they usually grow along streams or near springs. Frequently they are seen along dry ravines where their thirsty roots tap the subsurface drainage that lies hidden below. Like the other plants however, when the supply of water becomes inadequate they shed their leaves and wait for the next spring. Fast growing, usually of large size, and wasteful of water where water is dear, the cottonwood seldom lives two hundred years while the twisted juniper on the dry, rocky ledge frequently lives as much as five hundred.
Inconspicuous through most of the year are the flowering plants. Some of these are annualsplants that grow from seeds, mature, bloom, produce seeds, and die in the span of a few short weeks. When the snows melt and the sun warms the earth, the seeds that survived the winter germinate. The usually barren hillsides produce spots of green that soon spread to form patches as more and more plants mature. Lupine and locoweed are purple and heliotrope splashes color along the roads, while the fragrant, white, evening-primrose dots the sandy hillside. Scarlet gilia and Indian paintbrush add a touch of red to the scene, and orange is provided by the mallow.
April, May, and early June provide the best flower show as spring rains supplement the moisture from melted snow. Their races won, their seeds produced, the annuals wither and fade away as the temperatures rise. By the first of July little remains of the splendid show.
Two plants do brighten the desert scene in August and September. Most common is the rabbitbrush, a plant that grows almost everywhere. It is rather inconspicuous except in late summer when its brilliant yellow blossoms turn the whole shrub golden. The other is the bee plant of which there are two species: one has yellow blossoms, and the other has purple. These tall plants grow along washes, stream courses, roads, and irrigation ditches. Their delicate blossoms are always surrounded by insects drawn by the nectar the flowers produce in great quantities.
These, then, are a few of the typical plants. Each has adjusted its needs to those limiting factorswinter cold, summer heat, and aridity. A great number of plants grow on the monument that have not been mentioned here, but they are like the typical plants and have similar ways of meeting the problems of survival.
Many people who profess an interest in nature admit they cannot get very excited about plants. Such disinterest may result in minimizing the importance of plants in the general scheme of nature. That would be a major error. The plants of the world are the foundation upon which other forms of life are dependent. They alone are able to utilize the minerals in the soil and convert carbon dioxide and water to carbohydrates. Because of these abilities, the parade of life has been able to advance only when the plants advance. In the present as in the past, the kinds and abundance of plants set definite limits as to the species and numbers of animals an area may support. Thus, if man changes the plants of an area he will surely change the animals too, whether he realizes it or not.
If you drive to the quarry in the heat of the day you will see only a few of the birds that live here. They don't like to hunt their food during those hot hours. Frequently a turkey vulture sails majestically above the plains along the Green River. Sometimes so high he appears to be a speck, his telescopic eye searches the ground for the carrion upon which he feeds. Another bird that does not mind the heat is Say's phoebe. He is usually found perched on a fence post, a wire, or a dead branch waiting for some insect to buzz by. A graceful, short flight, a pop of his beak, and then back to his perch to repeat the cycle again. As he sits motionless, his gray breast and darker gray head and back make him hard to see.
The time to watch birds is in the evening; as the sun sinks and the air cools, they come forth. Small gray-brown rock wrens hop among the boulders near the visitor center. Robins scurry through the leaves in the stream course below the Dinosaur Quarry. Here too, western flycatchers and Audubon's warblers search among the cottonwoods for insects. A flash of red and white is seen as a red-shafted flicker darts from its nest in the hollow trunk of a tree. The sky is filled with wheeling, twittering rough-winged swallows and white-throated swifts that descend from their nests on the cliffs to feed upon the gnats and other flying insects.
These are the birds that spend the spring and summer here. They raise their families and, young and old alike, depart in autumn when frost kills the insects upon which they feed. As they flee the cold of winter, they are joined by many other birds that make their summer homes at higher elevations or more northern latitudes. Ducks, geese, and swans join the hordes moving southward. So do the various shore birds, bluebirds, and hummingbirds.
But the sagebrush flats and brushy ravines are not left vacant by this wholesale migration, for as the summer residents move our the winter residents move in. The Oregon and gray-headed juncos spend the entire winter here. Great flocks of mountain bluebirds descend from the mountains and piñon jays make the hills resound with their screams. Canada geese and golden-eye ducks live on the Green River and remain until it freezes. The harsh croak of the raven is seldom heard in summer but often in winter.
Few birds live here in winter and summerthe golden and bald eagles, the red-tailed hawk, and the little sparrow hawk. Perhaps the most handsome year-round resident is the magpie with its long, iridescent tail, black and white body, and white patches on its wings. One other resident makes his presence known by his eerie cry on frosty, moonlit nightsthe western horned owl. He hunts every night, summer and winter, but is seldom seen. Occasionally he is disturbed upon his daylight roost and as he skillfully dodges through the junipers, he makes a joke of the story that owls don't see well in daylight.
The mammals that live in the vicinity of the Dinosaur Quarry are almost never seen. There are several reasons for thisalmost all of them are nocturnal, are very shy, and most of them are small.
In spite of their retiring habits, they reveal their presence in a number of ways. Patches of bare earth under sagebrush and nearby sandy slopes are crisscrossed with tiny paths beaten into the dust by deer mice. Along the river bank, gnawed tree stumps, a few fresh chips, and perhaps a webbed footprint tell us beaver have been active during the night. The paired hind footprints of the kangaroo rat are common on the hillside. Freshly fallen snow records the preceeding night's activities in perfect detail.
Were it not for the golden-mantled ground squirrels, our evidence of mammals would be mostly indirect. But these little fellows are very much in evidence all day long as they play around the visitor center and in the picnic areas. They are handsome too, with their alert black eyes, cinnamon neck and shoulders, and dark side patches with white stripes. Most people call these ground squirrels chipmunks because both are striped. Actually the two are easy to tell apart; the chipmunk's stripes run to the rip of its nose, but those of the golden-mantled ground squirrel extend forward only to the shoulder region. Any small, striped mammal seen near the quarry is probably a ground squirrel, as chipmunks are rare here.
The water problem is an ever-present one for the mammals as well as the plants. At first this may seem strange with the Green River so close and several springs in the hills, but most of the smaller animals have very restricted ranges. A deer mouse, for example, seldom travels more than 100 feet from his home burrow in his entire lifetime. The kangaroo rat and the desert woodrat also have limited ranges although theirs are somewhat larger than those of deer mice. The majority of such animals must meet their water needs without springs and seeps. How do they do it?
The food they eat contains some water. The green vegetation of springtime contains large amounts. Even air-dried foods such as seeds contain some. And these animals don't need much. Through the thousands of years these little creatures have lived in arid lands, evolutionary processes have altered their bodies and life patterns to fit the conditions under which they must live. Surely one of the most useful and interesting of their abilities is that of utilizing metabolic water. Such water is obtained through oxidation of hydrogen contained in food and is a by-product of metabolism. Putting it another way, during the digestive process these animals are able to manufacture water from the chemical constituents of their food and the oxygen in their blood. The amount of water thus obtained is between 70 and 100 percent of the dry weight of the food eaten. Thus some desert animals are able to live a normal life span without ever taking a drink, and probably many of them do.
Carnivores such as the badger and the coyote get some of their water from the animals they eat and may go for days without visiting a spring. But eventually they return to the river or a spring for a drink. This is no special effort as carnivores generally range for miles in search of prey.
Winter is a time of difficulty for most animals. Some of them like the ground squirrels hibernate and sleep the winter away, but the majority must rustle their "daily bread." Winter storms drive the mule deer down from the high country. Mice tunnel through the snow in search of food. The white-tailed jackrabbit and the snowshoe hare change their coats from brown to white. In particularly hard winters the animals die in great numbers, first the weak and old, then the young, and sometimes even animals in prime condition fail to survive.
The reptiles that make their homes in the Quarry Area of Dinosaur National Monument are few in number. The rattlesnake is rare and seldom seen. The only common snake is the bull or gopher snake. This snake can appear very threatening as it swells its body and hisses loudly, but it is not poisonous. Gopher snakes climb well and are often seen in trees where they hunt for eggs and young birds.
Two lizards are commonly seen here during the summer. The side blotched lizard is about 1-3/4 to 2-1/8 inches long with a somewhat longer tail. These small brown lizards are frequently seen among the rocks near the parking and picnic areas. The name, side-blotched lizard, is taken from the black or bluish-black area behind the foreleg of the males. These lizards are also called brown utas.
The western whiptail is also a very common lizard. As its name suggests, it has a very long slender tail which it lashes from side to side as it runs. This lizard is easily distinguished from the side-blotched lizard by its larger size, longer more slender tail, and the presence of bars and spots of black upon its back. In late summer junior-sized young whiptails appear, but their 3-inch total length is unimpressive compared to 8-inch adults. The young are quite handsome with pleasing body colors and bright-blue tails.
Often lizards are seen whose tails are missing. When the tail is pulled or injured it can be shed by its owner. The shed tail may wriggle for several minutes and attract the predator's attention while the lizard escapes. The tailless lizard soon grows another one that is usually recognizable by its subdued or otherwise different color pattern. Sometimes the broken tail does not fall off so it and the new tail form a fork.
In summary then, we see that this apparently lifeless desert does support a wide variety of living things and a great number of individuals. Some of them, the plants and small animals, live here all year round while others, such as most birds, live here only part of the time. But whatever the length of stay, all living things must adapt themselves to existing conditions at the time of their stay. If they cannot adapt to static or changing conditions they must move or become extinct.
Some 60 million years have passed since the dinosaurs ruled the world. In that time mountains have risen, wasted away, and risen again. Glaciers have come and gone. Many species of plants and animals evolved and passed on to extinction. Every life form meets the testadapt or die. That test is as real to the dusty lizard basking on the quarry face as it was to the dinosaurs whose bones you came to see.