DISTRIBUTION AND HAUNTS
The platypus is confined to that part of Australia which lies east of
138° E. long., and to Tasmania. It has not so far been recorded from
the Cape York Peninsula north of 15° S. lat.; but this country is
little known, and it is not improbable that the animal will be found
there when the rivers are examined. The most northerly rivers from
which we have definite records are the Mitchell and its tributaries
on the western side, and the Barron on the east. A number of rivers
farther to the north--such as the Coleman, Archer, and Batavia, running
into the Gulf of Carpentaria, and the Normanby and Kennedy rivers
entering Princess Charlotte Bay--are probably suitable as habitats, and
may in time be found to contain _Ornithorhynchus_.
The first record of the platypus in the Gulf rivers is given by
Armit (1878, p. 413). He observed one swimming in a large water-hole
150 miles west of Georgetown on the road to Normanton. It is not
clear whether this water-hole was part of a river bed; but it could
not, in any case, have been far away from the Gilbert River, along
which the road runs. He also stated that platypus occurred in the
Leichhardt River, which is the most westerly record. Waite (1896)
published records from the Norman River at Normanton on the Gulf
side, and from the Barron, Herbert, and Burdekin rivers on the east
coast. Through the kindness of Mr. H. A. Longman, of the Queensland
Museum, Mr. A. H. Chisholm, and a number of other correspondents,
I have gathered a considerable series of records for Queensland
waters. The platypus is exceedingly plentiful in the upper waters of
the Mitchell and its tributaries, in the Barron, and the Herbert,
especially on the tableland. It is also common enough in the small
creeks draining into the Herbert below the range. It would seem to
be almost equally plentiful in all the chief coastal river systems to
the south--Burdekin, Fitzroy, Burnett, and Mary--although it is not
so frequently seen in the more closely settled portions of the river
valleys. No platypus has ever been seen (so far as I can ascertain)
in the Diamantina and Cooper’s Creek, which drain into the interior;
nor can I find any records for the Paroo and Warrego. They are found,
however, in the Condamine, Macintyre, and Dumaresq rivers, and a
tributary of the last is named the Mole River from the occurrence of
the duck-mole in it. It was, indeed, on this stream that Caldwell
collected some of his material. Mr. Longman mentions that his Museum
has records of platypus from the Brisbane district in the early days,
but none of recent date.
In New South Wales _Ornithorhynchus_ is found in the upper waters of
all the rivers draining to the east coast, and even in small creeks
such as Ourimbah Creek, north of Gosford. It is especially numerous in
the trout streams of the southern Alps, both those draining into the
Murray system, and those running southwards into the Snowy. Inland,
the records cover the upper waters of the Gwydir, Namoi, Castlereagh,
and Macquarie in the north, but not the Bogan. In the south, the upper
waters of the Lachlan, Murrumbidgee, and Murray still hold a goodly
store. It will be remembered that the first platypus was discovered in
a lagoon off the Hawkesbury. Two correspondents of the Sydney _Daily
Telegraph_ mention the occurrence of the animal in swamps and ponds
not directly connected with streams. Mr. C. R. Stranger, writing from
Curlewis, states that, when the great drought broke in June and July of
1920, the Curlewis swamp, which had been dry for several years, filled.
Soon afterwards a platypus was seen in the swamp, and was there for a
considerable time, always about the one spot. The swamp was four or
five miles from the nearest stream, the Mooki River, though the two
waters may have been connected by a backwater during the flood. Mr.
George Boyd has often seen platypus in swamp lagoons of a permanent
nature, situated in the neighbourhood of Wyong Creek but not connected
with it except in times of flood. A third correspondent describes the
finding of a platypus, after a thunderstorm, in a small water-hole in
the rocks near the top of Black Mountain, a few miles from Dundee, and
three or four miles from the nearest permanent water.
Krefft in his _Catalogue of Mammals in the Australian Museum_ (1864)
records three females in spirits from the Botanic Gardens; but these,
if taken from the ponds, must have been previously released in them.
He also records an adult male from North Shore, Sydney, and a female
from George’s River, from both of which places they have long since
disappeared.[15] The upper reaches of the Nepean and its tributaries
are, however, still tenanted, so that the platypus still occurs fairly
close to Sydney.
The Victorian records include most of the southern tributaries of the
Murray system, such as the Campaspe, Loddon, and Avoca rivers. The
Snowy River, to the east, has already been mentioned. Kershaw made his
observations upon the Hopkins in the west, and there are records from
the Glenelg, close to the South Australian border. Mr. Noel Learmonth,
writing to the _Australasian_ (30 June, 1923), comments on the fact
that the platypus is absent from the Eumeralla, Darlots, and Fitzroy
rivers, though inhabiting the Wannon on one side and the Hopkins on the
other. Mr. E. R. Waite, Director of the Adelaide Museum, has kindly
supplied the known South Australian records--the Murray River at Murray
Bridge and Tailem Bend, the Onkaparinga River, and the Glenelg, which
just crosses into South Australia close to its mouth.
For information as to the distribution in Tasmania, I am indebted to
Mr. Clive Lord, Director of the Tasmanian Museum and Art Gallery. He
writes:--
“This species is generally distributed throughout Tasmania. From
personal observation I can state that it can be found in most of the
inland lakes that are not close to the settled areas. In certain
of the National Park lakes (Mt. Field--20 miles NW. of Hobart) the
platypus is numerous, and, as the area is an absolute sanctuary
for our native fauna, it has a chance of living there in peace;
but, despite the fact that the platypus is totally protected by
law, they are very largely taken in other parts. At the Great Lake
large numbers were captured for their skins, but we could not get a
conviction. During the recent Christmas holidays I saw numbers in the
lakes in the Cradle Mountain and Barn Bluffs district (NW. Tasmania).
Along some of the rivers of the NW. coast the platypus is still to
be found; but, generally speaking, the advance of settlement is
reducing the number in the rivers, and the mountain lakes will be its
stronghold in the future. There are numbers in Lake St. Clair, and,
as previously noted, they frequent even the highest alpine lakes,
over 3000 ft. above sea level.”
This sketch of its distribution shows that _Ornithorhynchus_ is still
widely spread throughout the eastern portion of the mainland and
Tasmania, and is in no immediate danger of becoming extinct provided
present laws are enforced. It is very probable that closer observation
would discover its presence in many streams where its existence is
wholly unsuspected, and it is remarkable that it has not been recorded
from main rivers such as the Darling and Murray and the main channels
of their larger tributaries, such as the Lachlan and Murrumbidgee.
Although the creature seems partial to high places, it cannot be
influenced altogether by altitude, for it occurs commonly throughout
the low creeks and rivers of the coastal plain. Nor is rapidly running
water essential, since the Tasmanian lakes are so well stocked.
Certainly the platypus prefers clean, clear water, but it manages to
survive quite comfortably in rivers like the Mary and the Burnett,
which are far from being limpid streams. This, however, may be a matter
of necessity, not of preference. It is probable that it finds a greater
abundance of the food that most delights it in the more rapid waters of
the upper stream. It may be, too, that the occurrence of large Murray
cod (_Oligorus macquariensis_) in the larger rivers of the plains
has something to do with the matter. The platypus, foraging blindly
under water, or floating idly at the surface, would have no protection
against these voracious creatures.
[Illustration: PLATYPUS MANOEUVRING ALONG A SANDY BOTTOM.
The hind legs are kept stationary to balance the buoyant body (or, to
use a nautical phrase, to maintain an even keel). The one on the right
is touching the sand with its muzzle, its right paw is fully extended,
and the left is being brought forward for the next stroke. The finished
stroke is shown by the position of the fore-paw (close to the body) of
the one swimming on the left.
_Plate 25_]
The antiquity of the platypus, and the changes in river systems during
the ages, render it probable that the animal inhabited at one time or
another all the waters of Tasmania and of eastern Australia. Closer
settlement is very likely responsible for its disappearance from
certain rivers of the (Australian) coastal plain, and, as that area is
not now subject to general flooding, it is hardly to be expected that
the denuded rivers will ever be replenished with platypus by natural
means.
That the platypus does travel over land is quite satisfactorily
determined. But how far it can travel is not known. During floods
it has to move about in search of food, and usually works towards
the top of billabongs and backwaters, where supplies are more easily
obtainable. As the waters recede, it is often left isolated in some
deep water-hole, where it may continue to live happily for a time.
Ultimately, however, it makes back to the main water, either by
following the channel, or, if the river be nearer by another way,
by cutting directly across country. I have observed this happening
on many occasions, and have no doubt that the platypus possesses
a highly-developed sense of direction, by means of which it makes
straight for water. Animals released close to, but out of sight of,
water, never hesitate; they make straight off towards the water closest
at hand. In corroboration I quote the following paragraph from the
_Northern Daily Leader_ (Tamworth, N.S.W.) of 6 April, 1922:--
“The duck-billed platypus at times shows a remarkable knowledge of
locality. I carried one in a bag from its native river, where it
was caught on a night-line set for eels, to a shallow lake about a
mile away. It was then gently slid into the water, but promptly swam
ashore and started on the long crawl, straight for the home river.
The duck-bill was recaptured and returned to the lake, which, it may
be remarked, had no banks suitable for a platypus burrow. But again
the animal swam out and made tracks for the old address. Eventually
the beast was put far out in the lake and left to its own devices.
A few days afterwards it was found dead in a patch of scrub about
half-a-mile from the river in a direct line with the pool from which
it was taken.”
The observations of correspondents indicate that the animal can cover
a land distance of four or five miles, and may cross intervening high
land. Since it has considerable powers of endurance, and, despite
its voracious appetite, can survive without food for comparatively
long periods, it is possible that it has managed to contrive its own
distribution by direct means.
Platypus have often been observed working in a general direction either
up or down stream. These movements are almost certainly influenced by
food conditions. A migration of platypus was observed by the late Mr.
William Hill in 1859, when he was manager of the Pallamallawa cattle
station (now a township) on the Gwydir River. About fifty aborigines,
under ‘King’ Binamoore, were camped on the river-bank not far from the
homestead. One evening Mr. and Mrs. Hill strolled down to the camp
for a yarn with Binamoore, who was an old friend, but the chat was
interrupted by a sound from up river, similar to that made by a mob of
cattle fording a stream. Always on the alert for movements of his herd,
Mr. Hill, accompanied by his wife, walked down to the water’s edge to
investigate. The river at the time was low, but still flowing, with
occasional deep holes, connected by rapidly running shallows. Presently
the noise was heard again, this time closer at hand, in fact so close
that Binamoore and his tribe, and the tribal dogs, took fright, and
bolted off to the next station, deserting their gunyahs. Mr. and Mrs.
Hill then clearly observed a mob of platypus all swimming together at
top speed with the current, and estimated that there were at least a
hundred of them. There could be no doubt about the identification, as
the animals were frequently obliged to expose themselves in climbing
over obstructions in the shallows. On the following morning only an
occasional platypus was to be seen, floating at the surface or swimming
about in a leisurely way. I have every confidence in my informants,
each of whom has repeated the story to me several times. I know of
no other record of any mass movement of platypus, and my explanation
is that the mob had gradually congregated from streams in which food
supplies had been affected by flood, and were following the main
channel in search of further supplies.
To anyone knowing the rivers and lakes mentioned in the records of
distribution it will be obvious that the platypus inhabits a varied
range of waters, from clear, icy, rapid alpine streams of the southern
Alps to warm, turbid waters of the Queensland coastal plain, and from
large lakes to small waterholes. Despite this apparent catholicity of
taste there are certain conditions which determine the parts of these
various waters chosen by the animal. The chief is that of abundant food
supply.
Semon (1894, p. 10), who made careful observations on the Burnett,
writes:--
“_Ornithorhynchus anatinus_ inhabits the banks of running water
within the area of distribution. It follows these from their source
of origin down to the plains. The main condition for its occurrence
is the scooping out of comparatively expansive depressions in the
bed of the river, in which the water flows slowly, so that fine
silt collects on the bottom and a vegetation of aquatic plants can
develop, which serves as a resort for innumerable aquatic creatures,
worms, crustaceans, larvae of insects, and molluscs. Here the
Duckbill seeks its food, and hides from its hunter by diving. Here
it can remain in periods of extended drought, which dry up the rest
of the river bed, in a small amount of water. At such times those
Duckbills which live in the smaller waterholes, so soon as the level
of the water sinks too low, wander out into larger holes which are
less likely to dry up. Then one notices an increase in the latter,
and a coming together of the platypus folk.”
My own observations in the Manilla and New England districts confirm
this statement. There the streams are partially blocked at frequent
intervals by granite boulders, and a succession of quiet pools is
formed between stretches of rapidly running water. In these pools the
platypus finds its food. When freshes come down the river, however,
coarse sand and gravel are deposited on the silt bottoms, and for a
time the feeding-grounds are spoiled. At such times the animal is
forced to seek for food where it may be found, and generally works its
way upstream. After prolonged floods the animals are often found in
considerable numbers dead upon the banks. This would seem to indicate
that they had starved to death, but it must also be borne in mind that
they dislike turbid water, and a continuance of disturbed conditions
may have some physical effect upon them.
Heat and cold appear to have little effect, since the platypus seems
equally at home in the warm streams of tropical northern Queensland and
at a height of 6000 feet on the Kosciusko tableland--which, though not
continuously snow-clad, nevertheless experiences falls of snow during
the summer.
[Illustration: (1) MALE PLATYPUS RUNNING AT TOP SPEED.
Note elevation of all except tail, which sometimes is hoisted also.
_Plate 26_]
[Illustration: (2) ANOTHER VIEW OF MALE PLATYPUS RUNNING AT TOP SPEED.
Note powerful thrust of hind foot.
_Plate 26_]