CHAPTER X. Habits

HABITS

The early records contain little in the way of precise information as to the general habits of the platypus. Bennett (1860, p. 95) complains that, as long ago as 1829, “notwithstanding all the inquiries I made of persons long resident in the colony, I could get no correct information; I found then, as I have found during an extended residence in the colony, that the majority preferred forming theories of their own, and arguing upon their plausibility, to devoting their time to the collection of facts.” It is the same to-day.

Bennett went out to seek his first platypus at sunset, “knowing, as I did, the crepuscular nature of the animals,” and it was not long before his companion directed his attention to one on the surface of the water, not far from the bank on which they were standing. He writes (loc. cit., p. 104):--

“In such circumstances they may be readily recognized by their dark bodies just seen level with the surface, above which the head is slightly raised, and by the circles made in the water around them by their paddling action. On seeing them, the spectator must remain perfectly stationary, as the slightest noise or movement will cause the timid creature instantly to disappear, so acute are they in sight or hearing, or perhaps in both; and they seldom reappear when once frightened. By remaining perfectly quiet, however, when the animal is paddling about, it is possible to obtain an excellent view of its movements on the water; it seldom remains longer than one or two minutes playing on the surface, but dives, and reappears a short distance above or below the place at which it was observed to descend. Although the animal may ‘come up’ close to the place where the sportsman is standing, it would be useless to attempt to level the gun, for that action alone would cause its instantaneous disappearance; but, after waiting patiently until the animal dives, and watching the direction in which it sinks, preparation must be made to receive it with the discharge of the piece instantly on its reappearance at the surface, which (when it descends unfrightened) is almost certain to take place in a short time.”

And again on p. 108:--

“These creatures are seen in the Australian rivers at all seasons of the year, but are most abundant during the spring and summer months, and I think a question may arise whether they do not hibernate. The best time for seeing them is early in the morning, or late in the evening. During floods and freshes, they are frequently perceived travelling up and down the rivers: when going down, they appear to allow themselves to be carried by the force of the stream, without making any exertion; but when swimming against the current, their muscular power is exerted to the utmost to stem its force, and generally with success. I recollect, however, seeing two make repeated and ineffectual attempts to pass a small waterfall in a rapid part of the river, and, after many persevering efforts, they were unable to attain their object. The opinion that so generally prevails that these animals must be shot dead instantly, or otherwise they would sink and not reappear, I did not find from my own observations to be correct.”

These observations are of special interest, since they were made as long ago as 1829 in a district which had but recently been settled, so that the platypus could not have had time to alter its ways on coming into contact with Europeans. More than sixty years later the distinguished German zoologist Richard Semon spent some time on the Burnett River, where he reports that the platypus was very plentiful and was not molested by the white colonists or hunted by the aborigines. His account of its habits agrees in all essential particulars with that of Bennett. In the English translation of his popular account of his journey (Semon, 1899) will be found a summary of his observations; I prefer to give a translation from his paper in the Forschungsreise, which is somewhat fuller. He writes (p. 10):--

“On the Upper and Middle Burnett, where alone I observed the animal, it was plentiful everywhere in suitable localities along the river. In Ornithorhynchus a considerable preponderance of males over females was observed, so that for each female captured there were two or three males. As in Echidna, the fully grown male is larger than the female. Like Echidna, too, Ornithorhynchus does not lead an exclusively nocturnal life. More than once I saw the animals swimming in the river in daylight, searching for food; yet this could be termed exceptional. It is during the twilight of morning and evening that the animal leaves its home and passes to the water. Generally they turn to the river shortly before sunrise, and remain there till the sun has completely risen. In the evening it is the same--from a short time before sunset to a little while afterwards, a period of twenty to thirty minutes. This holds good for the winter months, from June to the beginning of September, when the nights are cold and the thermometer in the mountainous regions of the Burnett is almost at freezing point. One is then sure to meet with plenty of Ornithorhynchus at suitable places both morning and evening; and now and again to see them in broad daylight. This is changed, however, when the Australian summer begins. The days become hot, and the nights warm. In the middle of September, during 1891 and 1892, I very seldom found an Ornithorhynchus in the river during the morning and evening hours, and still less frequently by day. Doubtless they then use the nights for these excursions, for they must enter the water to obtain their food. I took great pains actually to observe the animal in the river by night. I did not succeed, however, nor even in bright moonlight. Since, however, Ornithorhynchus lies flat like a plank in the water, scarcely projects beyond the surface, and is absolutely noiseless in diving and reappearing, one would need an exceptionally favourable occasion to perceive and observe the animal by night.

“In the cool part of the year, on the other hand, I could observe the behaviour of the animal in the river during dawn and during daylight as long as the sun was low. As has been already mentioned, Ornithorhynchus lies quite flat in the water, with only the flat head projecting, and that very inconspicuously. Usually the animal lies motionless at the surface. After a few minutes it dives suddenly and noiselessly, stays under water two or three minutes, and comes up again just as suddenly, and just as noiselessly. During its dive it has collected by means of its flat bill, after the manner of a duck, all sorts of aquatic life, and richly filled its cheek-pouches. The reappearance takes place in order that it may get air, and chew and swallow the contents of these pouches....

“If an animal is frightened while in the water, it dives immediately, and does not reappear. Although it is a good diver, it can only spend a certain amount of time under water. Those which become accidentally caught in fishing-nets at night, and are held fast for a long time under water, are always found drowned next morning.

“The pursuit of the animal is not difficult if one knows its habits. Small as is its eye, and deeply buried in the fur as is the opening of the ear, yet sight and hearing are distinctly sharp; it is therefore useless to begin matters by trying to creep up while the animal is at the surface. The position of the eyes enables it to observe exactly what is going on on the rising banks above it. It does not recognise danger, however, unless the observer moves. But the mere lifting of a gun is sufficient to scare the animal away. Every dubious noise causes it to disappear.... Once scared off, the animals nearly always seek their homes, and do not reappear during that same morning or evening. And yet, it is easily taken if one approaches while it is under water, and at once stops motionless when it appears.”

These accounts of two very competent observers, both made in districts where the animal had not yet been disturbed or harassed, show that the platypus has not developed its alertness and timidity since the advent of man. The same remark applies to its predominantly crepuscular habits. It has sometimes been erroneously claimed that these have been adopted to escape from man and his gun. It must also be remarked that the months during which Semon noted occasional animals in the water by day are those of the breeding-season. At that season, when opening up burrows containing suckers, I have frequently found that the mothers were absent. It seems certain that they are forced to feed at irregular times during the nursing period, and that this is the principal reason for their being found in the river in broad daylight.

As to the preponderance of males noted by Semon, here again we must consider the time at which the observations were made. Wilson and Hill (1908, pp. 33-4) state:--“During the breeding-season, however, the pregnant female appears to keep much more closely to the burrow, so that one may then commonly enough shoot five or six males to one female.” As far as my observations go, the sexes seem to be numerically about equal.

A few other earlier observations are of interest. It is worth remembering that Charles Darwin (1845) saw the platypus with his own eyes. On January 19, 1836, while staying a day at “a farm called Walerawang,” he had the following experience.

“In the dusk of the evening I took a stroll along a chain of ponds, which in this dry country represented the course of a river, and had the good fortune to see several of the famous Ornithorhynchus paradoxus. They were diving and playing about the surface of the water, but showed so little of their bodies that they might easily have been mistaken for water-rats. Mr. Brown shot one: certainly it is a most extraordinary animal; a stuffed specimen does not at all give a good idea of the appearance of the head and beak when fresh, the latter becoming hard and contracted.”

Crowther (1879, p. 97) gives the only detailed description of its swimming motions known to me:--

“When swimming, the fore-paws are widely expanded, being convex forwards, propelling themselves by an antero-lateral movement. The hind paws and tail take but little share; the former have a slight lateral horizontal movement, the tail lazily moving with the body. When diving, the head is rapidly thrown beneath the body, front paws quickly moving until the bottom is arrived at, when they are seen turning rapidly over with their bills the sand, and even large stones.... A train of small bubbles proceeding from the nose marks the exact course the animal is taking.”

Crowther also states that the tail is the first part to reach the surface of the water.

Allport (1878, pp. 30-31) also watched ‘a large specimen, and one of that variety which has very red fur on the sides’ feeding over a gravelled bottom in the clear waters of the Mount River (a tributary of the Huon) in Tasmania; “his method of proceeding was to burrow his head and more than half the body amongst the stones, causing a cloud of sediment to rise at each dive.... He never remained under water longer than a trifle over half a minute, and stayed on the surface between the dives rather less than half a minute.” Allport also records that a large number of small bubbles were continuously emitted, and that the animal fed for three-quarters of an hour, and then went off to his burrow. I also have observed platypus feeding in clear water, and have seen them tear stones aside with their claws, or lever them up with their powerful bills and shoulders, to get at food underneath; but bubbles are certainly not emitted continuously while the animal is under water, as all platypus-hunters know. When it dives in alarm, the breath is apparently held, and no tell-tale bubbles issue. The first bubbles that come to the surface, after the animal dives, are not emitted by the platypus at all, but are formed by the imprisonment of air when the bill is suddenly submerged, and, as the body turns downwards, the bubbles traverse the contour of the back and break away at the rump to ascend rapidly to the air. This was formerly believed to be escaping breath; but as the animal, before sounding, undoubtedly fills its lungs to the utmost capacity so that it may remain under water, if need be, for several minutes in search of food, it is not likely to exhale until compelled to do so, and then only in brief spasmodic puffs.

From the sum of these observations, and without drawing further upon my own, we may safely conclude that the platypus is normally crepuscular, and was so before the advent of European man; that it resorts to the water twice daily to feed, and remains there for a period of from twenty minutes to three-quarters of an hour, perhaps longer when food is scarce; that the sum total of its aquatic life amounts to less than two hours out of each twenty-four; that it is so wary as to disappear for the day at the first sight of some unaccustomed movement on the river-bank, or the hearing of some unaccustomed noise close at hand; that while feeding undisturbed it remains at the surface for a period variously estimated at from rather less than half a minute to one minute, for the purpose of chewing and swallowing its catch, and then dives to collect more food, remaining under water for a similarly varied time; that in feeding it burrows with its sensitive, tactile muzzle among mud and stones, sometimes burying more than half its body, and thrusting fairly large stones aside with its powerful shoulders; that the greatly webbed fore-paws are the chief swimming-organs; and that, when floating at the surface, it lies flat, with the body just submerged except for the upper part of the flattened head and the middle of its back and tail, though occasionally it will be seen as in Plate 5, fig. 2.

Most of those which have occasionally been observed during the daytime (especially during the breeding-season) are undoubtedly females; but in well-shaded pools it is not uncommon to see individuals of both sexes abroad during the day. The time spent in feeding is bound to vary according to the supply of the invertebrate fauna and other commodities which constitute its food at that particular period of the year. Where food is plentiful, an adequate meal can be collected quickly, and the time required may be no more than Semon’s minimum of twenty minutes. The gravel bank referred to by Allport would not be so productive as a silt-bottomed water-hole, full of aquatic plants, in the Burnett, and it might easily take three-quarters of an hour to obtain a full meal. The nature of the food itself has been variously reported. For the Burnett, Semon (1894, p. 11) reports that the main food consisted of molluscs, and that the cheek-pouches were usually found to be full of immature individuals of a bivalve, Corbicula nepeanensis, 10 to 15 mm. in length. He mentions in addition, however, worms and insect larvae. Bennett (1860, p. 113) writes:--

“On examining the cheek-pouches or the stomachs of these animals, I always observed the food to consist of débris of insects of the family Nauceridae, very small shell-fish, etc., which were constantly found comminuted and mingled with mud or gravel. This latter might be required to aid digestion, as I never observed the food unmingled with it. The natives say that they also feed on river-weeds; but as I have never seen that kind of food in their pouches, I cannot confirm the correctness of the statement.”

Allport (loc. cit.) states that the food found in the cheek-pouches consisted of larvae of caddis-flies; Crowther found freshwater shrimps, water-fleas, and hard black beetles.

Wood Jones (1923, p. 55) notes that Bennett recorded the feeding of captive animals on freshwater mussels; but the mussels were broken up before they were given. From the nature of the masticatory apparatus he argues against shell-fish as a diet, and he concludes that common river-shrimps may be regarded as the staple article of diet. Since such thoroughly competent observers as Semon and Bennett have both actually found molluscs in the cheek-pouches, these cannot be put out of consideration as food. There is, moreover, a great deal of difference between the ‘very small shell-fish’ which Bennett mentions, and the large swan-mussels which were probably (though it is not specifically stated) the kind given in broken form to the captives. All observers agree that the platypus finds its food by nuzzling in the mud or gravel of the river-bottom after the manner of a duck. When it is remembered that its eyes are kept closed while beneath the water, it becomes extremely unlikely that the animal should catch such active creatures as freshwater shrimps except very occasionally. Crowther certainly mentions shrimps; but he probably refers to crustacea like the curious and archaic Anaspides, which is found in Tasmania among stones on the river-bottom, and which runs rather than swims.

The food of the platypus must necessarily vary in different places and at different times of the year, limited as it is to the invertebrate fauna present in the water at any given spot. It consists of immature molluscs, aquatic worms, the aquatic larvae of many insects such as dragon-flies, caddis-flies, may-flies, and the like, the larvae and perfect insects of groups such as the water-beetles and water-fleas--which are wholly aquatic--bottom-feeding water-bugs, and such crustacea as inhabit the bottoms of streams. This food is taken in with a certain quantity of mud or sand, which, as Bennett has noted, appears to be absolutely essential for the purpose of mastication. The living prey is killed while held in the long horny ridges situated in the anterior part of the mouth-cavity, and is passed rapidly backwards, being prevented from reaching the gullet by the bulbous hinder end of the tongue, and directed to one side or other by the tooth-like projections at the base of the bulb.

I cannot agree with Crowther’s observation that the tail is the first part of the animal to reach the surface. Apart from the inherent improbability that so cautious an animal should expose its blind end first, my observations, both in the open and in a tank in captivity, show that the tip of the muzzle is always the first part to appear, followed by the top of the head. The eyes immediately open, and, if there be no suspicious sight or sound, the rest of the body is allowed to float towards the surface, beneath which, however, it usually remains almost submerged. The animal floats in a spread-eagled fashion, with its webbed hands moving slowly, palms upward, to maintain its position, and causing the rings of ripples to which Bennett refers. Semon’s comparison to a plank is not very happy, nor do I concur in his statement that the animal usually lies motionless at the surface. Bennett (1860, p. 106) puts it thus:--

“When the fur of the Ornithorhynchus is wet, it has a sordid and far from attractive appearance, resembling rather a lump of dirty weeds than any production of the animal kingdom; indeed, were it not for their paddling motion on the water, these creatures would often escape observation; for their suppleness and colour, when wet, would cause them to be regarded only as masses of weeds, which are so often seen floating about the rivers.”

At the surface the animal chews the results of its catch in a leisurely manner, its jaws working laterally like those of a cow when chewing its cud; having swallowed the contents, it dives in search of more. In diving, the head is first immersed by bending the anterior half of the body downwards and almost simultaneously humping the back. The head is then flexed violently against the chest, giving a very powerful downward thrust comparable with that produced by a crayfish through the sudden flexure of its abdomen. This carries the body below the surface, a process which is aided by an upward thrust of the muscular tail. The webbed fore-paws are used alternately, the web being arched in the manner described by Crowther; the feet and tail trail behind. The animal swims in a determined fashion, at a steady but not fast pace, to the bottom, which is first touched by the tip of the muzzle. The fore-limbs are now laid back beside the trunk, and the webs are kept beating upwards, to hold the animal at the bottom. The body is strongly arched, the sides of the tail curve inwards so as to produce a concavity of its lower surface, and the end of this concave surface is applied to the bottom as if helping to keep the platypus down. In this somewhat constrained position it ‘bobs’ along the bottom of the river, testing every part with its tactile muzzle. It has every appearance of having to work hard against a natural tendency of the body to float to the surface. After two or three minutes it raises its head, relaxes the tense attitude of its body, immediately begins to float upwards, and hauls itself to the surface hand over hand by means of the webs of the fore-paws. If suspicious or frightened, it may merely show enough of the tip of the muzzle to expose the nostrils, take in a new supply of air, and dive again immediately. When the animal is undisturbed, the dive is practically noiseless; but when it is alarmed, there is often a distinct double splash made by the almost simultaneous strokes of head and tail, one downward, the other upward.

The swimming motions described above are those employed during feeding-time. When the platypus is definitely on the move, it swims fairly rapidly at the surface, and frequently raises its head out of and parallel with the water, so that it looks rather like a duck. Both myself and the late Charles M. Hoy have on several occasions noticed another kind of progression in the water. The naturalist’s way of collecting platypus is not to shoot it, but to place a bullet from a heavy rifle beneath it when the animal is floating. The concussion from the impact is usually sufficient to kill it out-right; but sometimes it is only temporarily stunned, and, on coming to, makes for the bank, where it can be easily secured. When a platypus has been temporarily stunned by concussion, and then recovers, it can almost be declared that when forging for the bank, it actually crawls along the surface of the water, for the fore-paws can sometimes be seen clearly above the surface, which the tail frequently lashes. On such occasions, two of which I have witnessed, the pace is decidedly fast and noisy, while the water is beaten and churned considerably by the action. Hoy, writing to me from Ravenshoe in northern Queensland on September 3, 1920, describes an uninjured male doing much the same thing:--“Saw male and female evidently copulating, and secured female--left ovary very much enlarged. Although usually very shy, the male came to the surface and swam up to within three feet of me, while I was taking the female from the river. He elevated his head from the surface of the water, splashing vigorously with his limbs and tail and taking on a very pugnacious attitude.” It is worth noting here that this particular male persisted in his charge until he was within three feet of Hoy, although the latter tried hard to frighten him back by throwing up his hands. Hoy admitted to me later that he was afraid of being spurred by the “hissing” ferocious creature. On the strength of this authentic observation, made in broad daylight, and of others that I have made at dusk, I am quite convinced that this method of swimming is also indulged in during nocturnal frolics. Apart from the actions of the infuriated male encountered by Hoy, platypus cautiously submerge themselves to the extreme during the daytime; but this is not the case when darkness sets in, principally because their vision then becomes acute. The late Geoffrey Smith (1909, p. 124) has observed this mode of swimming, and writes:--“I was surprised at the extraordinary tameness of the Platypus, several of which swam quite near the boat with the whole of their body exposed above the water and shining with a curious grey appearance in the sunlight.” This occurred at Mount Read, in north-western Tasmania.

Semon has observed that a platypus which has been shot and killed invariably floats high out of water. I can substantiate his statement, and have observed also that the submerged animal has to work continuously to keep itself down. Just how it manages to float with the body submerged in the way described above I am not certain, but the slight motions of the hind limbs and tail probably aid in this act. The swimming stroke of the fore-paw is outwards, backwards, and upwards, and ends with the hands palm-upwards against the sides of the body. When performed slowly and gently, this stroke would serve to pull the fore-part of the body down in the water. As the limb is thrust forward again, the resistance of the water keeps the web folded on the palm, until it is voluntarily extended to begin a new stroke (see Plate 25).

Note upturned palms, also stain on breast, probably due to secretion from scent-glands.

Plate 27]

On land the progress of the platypus is not nearly so happy. The web of the fore-paw is folded under the palm, and the two limbs of one side are rotated outwards and forwards together. The nails of the fore-paw take a grip, and the creature pulls itself forward, going over on its knuckles as it does so. Meantime the backwardly directed claws of the foot have taken purchase, and the body is levered forward on the right limb. Then the limbs of the other side come into play. The result is a shuffling, sinuous motion, resembling, as I have said before, that of a heavy-bodied lizard, such as the Blue-tongue (Tiliqua scincoides). Both the trunk and tail drag upon the ground. Considering how clumsy its method of locomotion is, it is surprising how fast the platypus can move when it has need of haste. When going at top speed, it can raise its body almost completely from the ground, as the photograph reproduced in Plate 26 shows, and can travel on level ground at the rate of 200 feet per minute (by stop-watch).

The platypus cannot remain for any great length of time in water without some means of resting, otherwise it will become exhausted and drown, for it must be remembered that the platypus is a mammal and resorts to water mainly for its food, after which it must dry its coat and retire to its burrow for warmth. A freshly-trapped robust male was placed in an open tank while I leaned over so that it could clearly see me. The animal immediately dived and, by maintaining upward pressure with its fore-paws reversed, remained at the bottom for several periods of six minutes each, with intervals of one minute at the surface, during which it exposed the tip of its bill as far as the nostrils. While collecting two specimens of brooding females for the University of Sydney, and as they had to be killed in the process, I took the opportunity to ascertain that they survived 5½ and 6 minutes respectively before drowning in small wire cages. These observations do not prove that the male can stay under water longer than the female, as, during a test made midway between breeding seasons, a female survived for 10 minutes. This is by far the longest period which I have observed.

The aquatic life of the platypus occupies but a small portion of its time. Besides feeding and tunnelling, its only other duty would seem to be that of making its toilet--the rest of its time being spent in sleep. It performs its toilet, as a rule, while resting on the bank, or at all events rids itself of most of the moisture from its fur before going off to continue toilet operations in its resting-burrow. Bennett (1860, p. 119) gives an account of the operations performed by a captive which was tethered by means of a cord attached to one leg:--

“After it had wandered some distance up the chain of ponds, feeding about the shallow water and mud near the margin, it crawled up the bank, and, lying down on the grass, enjoyed the luxury of scratching itself and rolling about. In this process of cleaning its skin, the hind-claws were brought into use--first the claws of one hind leg, then those of the other; but finding that it could not use the one to which the string was attached so well as the other, which was disengaged, after repeated trials it gave up the attempt. The body, being so capable of contraction, was readily brought within reach of the hind feet, the head also coming in for its share of the process. The animal remained for more than an hour cleaning itself, after which it had a more sleek and glossy appearance than before. Placing my hand on a part which it was scratching at the time, the claws passed over it instead of the animal’s body, when I found that it performed the combing in a remarkably gentle manner. On my attempting to scratch the place gently, it started away, but not far, and soon resumed the method of cleaning itself, which I had interrupted.”

From personal experience with platypus in captivity, I am convinced that Bennett’s tethered specimen was actually dying of shock and starvation the while he imagined it was enjoying the pleasure of scratching itself and rolling about.

Bennett also describes the animal as preening its fur with its muzzle, like a duck. Semon (1894, p. 11) records that on two occasions he saw duckbills lying in the grass on the river-bank, stretching themselves and cleaning their fur.

My observations show that the hind-claws play the principal part in toilet operations, but that the fore-paws are used as well. The animal squats on its haunches, and by its gymnastic ability is able to bring almost every part of the body within reach of one or other of the hind feet. It aids this process in a rather ludicrous way by pulling the loose skin round into the desired position with the paws, the webs being extended but not expanded in the action. It also cleans itself with bill and fore-paws, just as a seal rubs itself with the hairy palm of its flippers while lolling in calm water. I have seen a wet platypus sit up and pull its exceptionally loose skin about with its fore-paws, as if actually massaging itself. The pressure of the broadened claws against the intervening thin webbing is evidently quite sufficient for that particular phase of its toilet. In that case the webbing serves for a rub-down in the same way as a moistened chamois pelt, if nothing more. Seeing, however, that the fore-claws are used principally for scratching into solid soil, and that the versatile and oscillating hands are adapted for grasping, the platypus may readily transform them into excellent combs by merely palming the webbing, as when burrowing, walking, running, or climbing, and may use them for combing the parts which cannot be reached with the hind-claws.

In respect of thorough cleanliness the platypus easily holds its own among mammals. In person and in dwelling-quarters, even when brooding, it always exhibits conditions exceptionally tidy. How different is this monotreme from its only known living relative, the echidna. To my mind, as regards toilet at least, the contrast is extreme. Every time I have examined a freshly-caught platypus--wet or dry, young or old--it was particularly clean in skin, pelage, and external orifices, such as facial furrows, nostrils, etc. Of course, this may be partly due to its semi-aquatic nature. Its water-dreading cousin, meanwhile, is about the dirtiest wanderer afoot. Quite apart from its perpetually begrimed muzzle and snuffling nostrils, the eyelids of an adult echidna of either sex are frequently found to be caked with a mixture of earth and secretions from the eyes, while the skin of the abdomen and the hair thereon are seldom found to be clean. Again, the temporary pouch of the female echidna, prior to weaning the occupant, is filthy, and this condition is certainly not entirely due to milk stains. Obviously, then, it is a blessing for both that the pouch is not a permanent feature, otherwise the mother would have to evolve something better than awkwardly-turned toe-nails and, possibly, a tacky tongue to complete her so-called toilet. Incidentally, it is fortunate for the young one that it is transferred, in a lethargic state, to sweeter quarters before attaining sufficient sense to observe its surroundings.

Though I have often disturbed platypus on river-banks, I have never seen them engaged in performing their toilet in the open. They resort, as a rule, to flat ledges under projecting roots, or to similar cover; these places, judging from the tracks leading to them, and from the way in which they are flattened down as if through long usage, would seem to serve as toilet tables of a comparatively permanent nature--that is to say, regular resorts of a given animal while it is in any particular locality. In such a place the platypus, secure from observation, and able to slip quietly into the water at the slightest alarm, removes the water from its fur, and reduces the latter to that condition of sleekness which is so essential to its well-being. As with most wild animals, the first sign of ill-health is the neglect of toilet, and this neglect in the case of Ornithorhynchus is rapidly followed by death. I have frequently noticed that sickly and enfeebled animals will attempt to perform the toilet motions, but are so little able to correlate their activities that the claws pass helplessly up and down without touching the body at all. In this condition they take no heed of man’s presence, being practically unconscious. It should also be noted that the feet are used for scratching the body while the platypus is floating at the surface; but this is probably due to the irritation caused by parasites. Ornithorhynchus, although flealess, shares with a very few animals the rather doubtful distinction of having a tick, Ixodes ornithorhynchi, all to itself.

This same position is used in the nest during incubation and nursing of the very young.

Plate 28]

Its toilet completed, the animal retires to its resting-burrow to sleep. Between this burrow and the nesting-burrow of the breeding-season a sharp distinction must be drawn. Existing accounts of the habits of the animal assume that the nesting-burrow of the breeding-season is the home of the platypus all the year round. Nothing could be farther from the truth. The complicated nesting-burrow is constructed by a single female for the purpose of laying her eggs and rearing her young, and is not resorted to by any other individual. Resting-burrows are, however, made by both males and females at all times of year. They are usually semicircular excavations under the roots of large red-gum trees and the entrance at each end is concealed by overhanging ledges, generally in the neighbourhood of the ‘toilet tables.’ The diameter of these tunnels is irregular, but always much greater than that of the nesting-burrows; the sleeping-chambers, from one to three in number, are simply enlargements of the burrow, containing no sign whatever of nesting-material or bedding. These burrows appear to be either purely male quarters or purely female quarters, the sexes not being found together in them. At most I have found two males occupying a single burrow.

When the animals are on satisfactory feeding-grounds, such burrows appear to be used regularly by the same individuals. But when they are forced by flood or freshes to move elsewhere, it becomes necessary to find new quarters. During these times platypus are sometimes captured in hollow logs or, in districts where alluvial mining is carried on, in sluice-boxes. Under stress the animal appears to make use of any kind of cover available. The males evidently make their own camping-burrows, as they are frequently found with the bald patch near the end of the tail. This is caused, as in the case of the female, by plugging off undesirable subways, etc. Burrows used by males may also be distinguished from breeding-burrows by a foxy odour which is compared by Mackenzie and Owen (1919, p. 12) to that of an onion. The odour is caused by the secretion of the scent-glands, which are situated at the base of the neck, just in front of the shoulder (see Plate 27).

Although, except during the breeding-season, platypus may be considered solitary animals, they are occasionally found in company for short periods, when forced by seasonal conditions to migrate. The greatest number that I have observed at the same time was four, and they did not appear to be consorting with one another, but simply feeding about quite independently. On one occasion I unearthed two adult males which were camping contentedly together in the one burrow. On another occasion I secured two males in a “turret trap” which had been set in the early morning for only an hour and a half. On a third occasion three males were trapped in one night, either while leaving or entering a camping-bank beneath a giant red-gum--a “buck barracks,” as I have since named the haunt.

Although Bennett has made the suggestion that Ornithorhynchus hibernates, my investigations do not bear him out. In the New England district of New South Wales the pairing season commences in July, which is the midwinter month on those cold highlands. The platypus lives an active life the whole year through, and eats prodigious quantities of food.

The thing one first notices in a living platypus is its extraordinarily restless activity. It is far more difficult to hold than any other animal of its size with which I am familiar, not so much on account of the actual strength and violence of its struggles, but because of its persistence in them. Bennett frequently remarks on the way in which the “looseness of its integuments” renders it difficult to hold. He refers to the skin and its underlying muscle-layer (the panniculus carnosus), which, in most mammals a very thin sheet, is in the platypus a thick muscular jacket, with slits through which the limbs and tail project and with numerous strong slips attaching it to various parts (see Plate 10). The animal seems to be able to slip its body through this loose overlying sheet in an uncanny invertebrate fashion, struggling forward for a time, and then, when it finds its progress prevented, suddenly changing its direction and slipping backwards out of one’s hands. At the same time all four powerful limbs are brought into play, and the head, flexed downwards by strong depressor muscles, also helps in the struggle. The only way in which the animal can be held safely is by grasping the scruff of the neck with the left hand and the tail with the right. While most animals after a time resign themselves to the inevitable, the platypus continues to struggle until exhausted, unless one is fully acquainted with its ways and coaxes it (see Plate 28).

Many observers have borne witness to the nervous temperament and restless activity of the animal in captivity. Three individuals which were forwarded by me at various times to the Department of Zoology at the University of Sydney, in order that some observations might be made, were all very impatient of the excitement and fuss of constant inspection and handling, and none lived longer than seventy-two hours. As the animals are easily capable of standing fasts for much longer periods, death would appear to have been due to nervous exhaustion, and certainly not to inanition--although, it is true, they took very little of the food that was provided for them.

It does not seem that the platypus displays anything of that affection for its mate which is so characteristic of the behaviour of birds and higher mammals. The period during which the mated pair are together is short, and I have no evidence that the male takes any further interest in the female and its young when once impregnation has been accomplished. The solitary observation of Hoy, quoted earlier--which might be taken to mean that the male charged in defence of his mate--is equally open to another, and, it seems to me, a more natural interpretation. Anger at the actual deprivation may have played a greater part than affection, for the actions were those of an angry beast. Moreover, since the occurrence took place in broad daylight, it is possible that the animal had only a very incomplete conception of what was going on. Nevertheless it remains to the credit of this particular male, that he did not dive and disappear after the report of the rifle, and the impact of the bullet close to him in the water.

Nor would the female platypus seem to show any actual affection for her offspring. She uses great cunning to keep them safe, and sees to their physical well-being with meticulous care, reducing herself to a state of emaciation and exhaustion in the process. But she makes no attempt to stay by and defend them when a burrow is opened up, her chief anxiety being to escape. I have never known a female in the burrow to show fight, or attempt resistance of any kind. Yet, even so, she shows signs of agitation, which is more than some marsupials do. When one tears the young from the back of a koala (Phascolaretos) for instance, the mother, after one vacant look in the direction of her puling infant, goes on calmly chewing gum-leaves.

The male platypus sometimes proves both pugnacious and aggressive. One which I was using for photographic purposes showed a great dislike of the process and deliberately charged and bit me on the arm and fingers. I compare the bite--which was made with the anterior pairs of horny ridges--with that of a gander, and it was sufficiently severe to cause me to take precautions against further attacks. Since then I have experienced bites from both male and female platypus which were deliberately roused for the purpose.

How far it is permissible to attribute to intelligence habits of wariness and cunning which have become what we are pleased to call instinctive is a moot point. The wary ways of the platypus have been described more than once, and there is no need to repeat them here. We may, however, assume that these ways, though they are proving useful against the onslaughts of European man, were used before his arrival.