NATURE NOTES

New Zealand Herald, Volume LXXIII, Issue 22350, 22 February 1936, Page 27 (Supplement)

NATURE NOTES

BY B. A. FALLA

HABITS OF REPTILES

Tho student of natural history in New Zealand is not much concerned with the class known as the reptiles. Only two of the five existing orders of reptiles are represented here at all and they are not conspicuous, except for one outstanding and redeeming creature to be referred to later. The reptiles of the world to-day are degenerate as compared with their prototypes of bygone ages. Palaeontology, the study of the fossil remains of plants and animals, shows us that there was a period in the history of the earth when reptiles were the dominant animals. Of gigantic size they roamed the land, swam in the sea, flew in the air. Presumably they enjoyed warm climatic conditions in those days and were unable to withstand the rapid onset of a period of cold, for the epoch of giant reptiles terminated abruptly and they are known to-day only by the bones and remains which palaeontologists find, assemble and classify, honouring them with such unwieldy posthumous names as Plesiosaurus, Brontosaurus and Ichthyosaurus.

The earth to-day is undoubtedly a much cooler sphere than when these giant reptiles lived, and the modern reptiles show their dependence on warmth by a distribution that is largely tropical. The equatorial regions swarm with species and the few that exist outside it are active in summer only and pass the winter in dormant and helpless condition. In fact, only two of the five orders, the snakes and lizards, can exist at all in regions where winter temperatures are fairly low, and a great number of the species of lizards are of very small size. The other three orders are the Rhynchocephala, which is the most primitive and includes only one living representative, the New Zealand tuatara; the Chelonia, tortoises and turtles; and the Crocodilia, a name needing no interpretation.

This introduction all arises from a question, "What is the difference between a crocodile and an alligator 1 ?" I am answering it with an article on reptiles because, a bald answer to the question seems to me of little value to anyone. It might be of some use to know the difference if the two were in the habit of walking about together, but their ranges are quite distinct. In spite of local usage, such as "Queensland alligator," the fact is that all but one of the "crocodilians" found in the tropical belt of Africa, Asia, Australia and Central America are true crocodiles. The largest of them are over eighteen feet in length and they spend a somewhat sluggish existence in streams oi on muddy banks, preying upon such animals as they can seize when the latter are wading, swimming, or coming to drink. The females lay eggs which they bury in earth and leave for the warmth of the sun to hatch, but in one species at least the mother stands by to help the young at the time of hatching.

Alligators are structurally only slightly different, but are confined to rivers in North America and South America, with one species in China. The structural differences distinguishing them from crocodiles are the shorter and broader head; pits in the upper jaw for the first and fourth lower teeth, whereas the crocodile has a pit for the first and a groove for the fourth; and one or two other slight differences. Distinguishable from both of them is the gavial of the river Ganges and tributaries. The gavial has a long, narrow snout, v almost equally regular teeth, and is the largest of existing reptiles, attaining a length of thirty feet. The study of the life history of these great reptiles does not seem to have attracted many zoologists, and it is only lately that the common American alligator's life and habits have been adequately described. This has been done by Mr. E. A. Mcllhenny, who has shown, as is so often the case, that a much maligned animal has many good points.

The fact is now established that the mother alligator defends her nest and takes care of her brood over one winter. Males have definite territory to which they return year after year and defend it by bellowing loudly and showing readiness to fight. When feeding on snakes, alligators show a remarkable ability to distinguish between venomous and non-venomous kinds. When a snake that happens to be poisonous is caught it is held in the alligator's mouth and shaken vigorously until quite dead. If, on the other hand, a non-poisonous snake is caught it is not shaken but killed by being crushed between the jaws. It further seems that alligators must rise to the surface if they are to chew their food. Objects that can be swallowed whole are disposed of while submerged.

By an accident of distribution New Zealand was isolated from adjoining land-masses before snakes had time to get here, and the powers that now control our destinies are determined that they never shall. A nice specimen intended for a zoo was publicly beheaded in Wellington the other day at the command of those in authority in such matters. It is a pity that such zeal and a similar ceremony did not attend tho arrival of the first rabbit, deer, stoat and weasel, to mention only a few of our more fortunate immigrants. In most parts of the world nonpoisonous snakes predominate, and a few species are protected by law as useful destroyers of rodent animals, but the reverse is tho case in Australia and New Guinea, where poisonous species are in the majority. Even there, snakebite is not common and due caution and a knowledge of treatment have done much to minimise the danger. Sea-snakes which swarm in some parts of the tropical Pacific Ocean are particularly deadly. They are stranded alive on New Zealand coasts occasionally, but cannot live on land, nor can they survive long in the colder temperature of tho local sea water.

The turtles of tropical seas sometimes reach New Zealand coasts, but not regularly, and their cousins, the land and fresh-water tortoises, are known hero only from specimens introduced as pets. A few that have escaped aro found from time to time at liberty and they seem to have no difficulty in surviving in a wild §tate hero. Recent captures in Auckland have been examples of three different species, one an Australian. one Chinese and one American.

There are about twelve native lizards already described in New Zealand, and any careful investigator would probably find several still undescribed. They aro not of a large or spectacular kind, being mainly small geckos and skiuks, whose habits, if not nocturnal, are at least always retiring. They are not without interest, however, and it will be appropriate to write about them more fully in this column at a later date.