At the present time these reptiles are not so very common. Ever-prevailing superstition among the ignorant and exaggerated bad reputation have brought on a relentless war of extermination against them, so that now in the neighborhood of settlements they are seen seldom if ever. Their center of distribution is more and more confined to the region along the banks of the Gila river in Arizona, although less frequently they may still be found as far west as the Mojave desert in California. But those are wrong who believe that the Heloderma is living only in the most arid portions of the southwest. There are several reasons why the reptile seeks eagerly irrigated places, which are productive of some vegetation, for it needs water, food and shady hiding-places.
In the middle of summer, when even the larger streams are dried up, the Gila Monster retires to some burrow, abandoned by another animal, or to deep crevices in the rocks, and spends there in a torpid state several weeks, until the great rainfalls relieve the country, give fresh plant life and fill again the barren riverbeds. This is the animal’s summer retreat. During the course of a year it takes a second and longer one, the regular hibernation, that lasts about from November to the middle of February, when it resumes its outside life again. It loves to bask in the still mild rays of the sun, but as soon as the heat increases the Gila Monster seeks shelter for the day behind stones and bowlders, under clumps of cacti and in small mesquite groves along the river banks. It roams about only after sunset or early in the morning. The idea that this lizard enjoys the quivering heat on an open Arizona plain, while other sun and heat-loving reptiles keep in hiding, is as erroneous as many others. Nothing is so absolutely fatal to the Heloderma as to be exposed only for half an hour to the direct rays of the sun in midsummer. Another reason why it prefers to live in the neighborhood of streams where plant life is more abundant explains itself by the necessity to provide for food.
Whoever has an opportunity to observe reptiles in confinement for an extended period of time can easily draw conclusions as to their mode of living in freedom. A captive Gila Monster is fed on hens’ eggs; in summer one each week, in winter one every two or three weeks. It refuses every other kind of food, however temptingly it may be offered, such as mice, frogs, angleworms, mealworms and the like. It is more than probable that in their wild state they live on a similar diet, consisting then of eggs of other lizards, of turtles and of birds. The animal has the reputation of being destructive to the Arizona quail.
Several writers of Natural History add to this a diet of insects, but the embarrassed locomotion of the Heloderma seems to exclude flying and fast-running prey. Nearly all reptiles which feed on eggs climb, as do some snakes, and as does the slow and clumsy Gila Monster. They are not able to ascend high and straight trees, which, however, are not found in these regions, but they are able to climb bushes and low trees, having somewhat leaning trunks and rough bark. And it is wonderful to see how cleverly it disposes of the sharp claws and the muscular, half-prehensile tail, both in dragging itself up and in retarding an often too rapid descent.
The inquiry may be made: How is it possible that a Heloderma lives on eggs alone when it can find them only during the relatively short time of five or six months? First, it may be remembered that this period corresponds nearly to the active life of the animal before and after estivation. The second and more important reason is its remarkable frugality. The digestive organs are so constructed that they adapt themselves to a fast of many months without injury to the animal.
In captivity the Gila Monster begins to slough about January and continues this process during several months. The epidermis comes off not like a snake’s, in a whole piece, but in several, or more frequently in many, fragments.
There is still a wide field open for accurate observation and definite knowledge that we relinquish to the professional naturalist and to those fortunate ones who can study the animal in freedom.
Amelia Walson.
[Editor’s Note: The Gila Monster of the illustration is still living and has for some years been the interesting pet of one whose love of nature in all forms has found beauty in the reptile usually shunned alike by the savage and by civilized man.]