The Mutton Birds of Bass Strait (1956)


[Music playing] (Narrator) A species of
petrel commonly known as the Tasmanian Mutton Bird returns each spring to
nest in the islands around south eastern Australia. They come from the north in
flocks totally many millions and migrate down the east
coast of the continent to their breeding
grounds in and around Bass Strait to the
north of Tasmania. [Music playing] One flock so impressed
Matthew Flinders during his exploration of the
Furneaux Islands in 1798 that he described
it in his diary: ‘There was a stream of from
50 to 80 yards in depth and 300 yards or
more in breadth and during a full hour and a half this
stream of petrels continued to pass without interruption at a rate little
inferior to the swiftness of a pigeon. From the lowest computation
I think the number would not have been less
than a hundred millions.’ These birds nest in large
numbers on scores of small islands in
the Furneaux Group and sealers who came in
the wake of Flinders were quick to exploit them
for food, fat and oil. Nowadays adult birds and
eggs are protected and the industry is restricted
to taking fledglings between two and three
and a half months old. [Music playing] In the Furneaux Group the mutton birding industry is
centred on five commercial islands. The largest is Babel so named by Flinders
from the confusion of tongues of its many kinds
of bird inhabitants, penguins, gannets, cormorants,
mutton birds and gulls. Other commercial islands in
this area are Chappell, Great Dog and Little Dog
and Little Green Island. [Music playing] For the people of Flinders Island
the opening of the birding on March the 23rd is
the event of the year. In the weeks before visitors
from the mainland arrive, the school closes, islanders
leave their farms. They make for Lady Barron
the small sea port at the south of Flinders Island. Cape Barren Islanders too come to take
their traditional part in the harvest. Boats are chartered and food
supplies, drums for oil, boxes, salt and all the paraphernalia needed
for six weeks’ stay are stowed aboard. Even a land Rover is
shipped to Babel. [Music playing] Small cutters are used to
reach the closer islands while larger vessels make the
voyages to Babel and Chappell. [Music playing] The birders land their gear
by dinghy on the small beaches or rocky shore
platforms below their sheds. Each shed unit is double, one
building for accommodation and the other for processing
the mutton birds. [Music playing] This is a busy time
for the birders, especially if a new
shed has to be built. Finally spits are sharpened and stacked ready for the
opening of the season. [Music playing] And so at dawn on March the
23rd the slaughter begins. The fledglings are removed
from their burrows and killed by a sharp
jerk of the arm. The catchers work systematically
through the rookeries and examine all likely burrows. They thread the birds by
their beaks on wooden spits made of Manuka the
local tea tree, keeping their heads upward to maintain
the crop oil, an important by-product. [Music playing] A good man’s daily tally is
very nearly a thousand birds and he carries his own
catch back to the shed. His average load might be 60 birds
and weighs about 120 pounds. [Music playing] At the processing shed the crop oil
is squeezed into a collecting drum. Twenty birds yield about a gallon
of oil at the peak of the season but there is none in
the last few weeks. After refining it will be
sold for medicinal use. After plucking the birds are scalded
and the remaining down is rubbed off. The carcasses are left to cool before
being opened up, dressed and salted. The main part of the
catch is salt cured. Weather permitting fresh birds are sent to the
freezing works at Lady Barron. [Music playing] Fresh birds are repacked in
flat wooden cases and frozen. In recent years relatively more of the catch has
been marketed in the fresh state, transported by air to
the consuming centre. Tasmanians are the
largest buyers, regarding the flesh of the
young bird as a delicacy. Over half a million birds were
taken in 1954 and they netted over 40,000 pounds for the
inhabitants of Flinders Island. How long can the rookery stand
such intense harvesting? Little wonder that the
government of Tasmania was concerned for the future
of the mutton bird, so the CSIRO joined forces with
the Fauna Board of Tasmania to investigate its biology
and life history. In 1947 a field station was set up
on Fisher Island off Lady Barron, strategically placed in the midst
of three commercial islands. A hut serves as a laboratory, living quarters and store
house for field equipment. On Fisher the biology of the mutton
bird is studied intensively, supplemented by excursions
to nearby islands. Statistics compiled
over a number of years will show whether the commercial
rookeries are being depleted and if so what measures must be
applied to maintain them. Tussock grass, poa pomiformis, which covers most of the island predominates in all the
rookeries around Tasmania. Between the tussocks
the birds scratch out their nesting burrows to a
depth of about three feet. Some birds also nest in this
little grove of Seaberry Saltbush and Coast Wattle on the
south end of the island. About 150 pairs of mutton
bird nest on Fisher but their presence is not
obvious in the day time. Even the entrances to their
burrows are hidden, partly covered by tufts of grass and
other debris blown there by the wind. After sunset the birds
return from the sea. On the larger island the air is
filled with flying, wheeling forms and the caterwauling of these hundreds
of thousands of birds is deafening. [Sounds of mutton birds] They land within a few feet of
the entrance to their burrows and make their way below ground. Mutton birds are particularly
helpless on the ground. Birds remaining on
land in the daytime do not leave the shelter
of their burrows as they are easy prey for predators
such as large gulls and hawks. [Sounds of mutton birds] Within an hour of the first
arrivals the pandemonium subsides but just before dawn it rises again
as the birds make their way to the take-off rocks for the
communal exodus out to sea. [Sounds of mutton birds] They do not easily
become airborne and usually make a running
take off into the wind or plummet themselves
from an eminence. Streams of departing birds
converge on rocky outcrops on the densely
populated islands. Prominent rocks are marked by
scratches of untold generations of birds which have used
them for take-off platforms. [Sounds of mutton birds] By dawn the birds remaining on land
are safely hidden underground. Here is one protesting adult occupant
of the Fisher Island burrows. The species derives its scientific
name Puffinus tenuirostris from the long slender beak which
is leaden grey in colour. The dusky appearance of the underwing
coverts is also characteristic although on some individuals
they may be almost white. The short fan shaped tail has given
the species its popular book name short tail shearwater. The legs are blackish
grey on the outer aspect and tinged with
purple on the inner. Notice on this bird’s leg
a monel metal ring. On Fisher Island every
mutton bird is banded and has it’s
distinguishing number. A census of the Fisher Island
rookeries is taken each season and to ensure that no
burrow is overlooked the island is surveyed
in narrow strips. Each burrow is marked
with a neat numbered peg and a detailed map of the
rookery is drawn up. Each ringed bird is
recorded in the field book as the occupant of a
particular burrow. A dab of paint of distinctive
colour on the stake indicates that this burrow
has been inspected. A precis of the field notes
is made in a card index with a card for every bird. Statistics from these records
reveal many interesting characteristics of mutton birds. For instance they are monogamous and
usually take the same mate each year. They return invariably
to the same burrow site even if the burrow has been
destroyed in the meantime. Female 12591 was first recorded
nesting on Fisher in 1948 occupying burrow 297 to which
she has returned ever since. She had the same mate til 1953 though
he was not checked in during 1949. They were divorced in 1953 and each took a new mate in the
same little neighbourhood. Banding experiments will
eventually make it possible to calculate the mean life
expectancy of mutton birds. Many of the birds
ringed in 1947 returned to Fisher Island for the
eighth successive season in 1954. As in most petrels both sexes
have similar external features but they are easily distinguished
in the breeding season. The unlaid egg in the
mother bird can be felt as a hard protuberance
in the belly region. The clercal(?) opening of the male
is inconspicuous, rounded and small while in the female it is a prominent transverse slit
with lips swollen and tumid. After egg laying the opening
becomes widely distended and the clercal(?)
lips bloodshot. The female lays only
one egg each year. The first eggs are laid about
the night of November the 21st reaching a climax by
November the 25th. The laying season ends about
the second of December. These dates have not varied
materially since the first observations were
recorded over a century ago. The egg is
disproportionately large. The adult bird weighs one
pound to a pound and a half while the egg averages
just over three ounces, about one sixth of the
bird’s own weight. Egg laying is a
considerable ordeal and the female after resting in
the burrow for a day or two goes out to sea to
feed and recuperate. The male remains sitting
on the egg alone and unfed until the female returns
about 13 days later. The parents continue to
change over every 13 days until the egg hatches, about
54 days after laying. Between the 13th and
the 23rd of January practically all eggs in
the rookery hatch out. When two or three days old the chick is left by its
parents in the daytime but at night one
returns to feed it a gargantuan banquet
of krill and oil. If neither parent returns it must fast
sometimes for as long as 15 days. At the peak of its growth the young bird averages a pound
heavier than the adult, often scaling two
and a half pounds. As the season progresses
the body weight falls, feathers appear and
the down is shed. The fledglings are finally deserted
by their parents in mid-April and now patrol the rookery at
night exercising their wings. They leave the island
when about 100 days old. When ready to depart they make their way to the water’s
edge or a suitable take-off point. With the coming of day
birds of prey drop down to feast on any fledglings
exposed on the ground. Others take to the water
and are soon on their way. [Music playing] The young birds feed at sea
to build up their strength before following the course
taken by their parents. The route cannot be
accurately plotted but the available evidence
shows their migration covers a vast circuit
of The Pacific. In late April and May many birds are reported
along New Zealand beaches and in the vicinity of
the Marshall Islands. In June they are seen near Japan
and along the coast of Alaska. They stay in this region til the
end of the northern summer, large flocks frequenting
the Bering Straits. By September the southward
migration is underway, down the coast of Canada
and across The Pacific. The adult birds reach
the breeding grounds soon after the third
week in September. The immature birds travel later and may continue to come in
until December and January. During the migration many
birds die or lose their way. The greatest losses occur
along the Australian coast where countless thousands
may perish each year, apparently through starvation. The mortality varies. Nineteen thirty four and the years
around nineteen forty were bad years. Another heavy mortality in 1954
was the largest yet recorded. How these losses affect bird
population strength is not yet known. The results of exploitation by
man are more easily determined. Before the yearly harvest a sample number of young
birds is banded at random throughout the
commercial rookeries. The catchers will retake
many of these birds and from the number of rings
returned after the season the intensity of harvesting
can be calculated. In 1954 1650 young birds were ringed
on four commercial islands and of these 60% were
retaken during the harvest. Yet despite this high
rate of exploitation the records show these rookeries
are not being depleted. Why then have mutton birds disappeared
from large areas on some islands? Investigations have shown grazing
animals to be responsible. The natural habitat
of the birds is disturbed by eating
down the grassy cover, trampling in the burrows
and hardening the ground. Soil hardness figures
determined with a penetrometer show that the harder the ground the fewer the number of burrows
occurring in any given area. Erosion is another
serious problem particularly on the
mainland of Tasmania. This sand blow at
Cape Contrariety was probably started by
rabbiters digging out burrows. Similar havoc is taking place
in some of the rookeries on Phillip Island in Victoria. It is comforting to know that
even though commercial interests take their yearly toll this in
itself does not harm the colonies. If only their natural
environment can be preserved there is no reason why the
mutton birds of Bass Strait should not fly for eons to come in the same thrilling abundance
which amazed Flinders and delights the present day
bird watcher and ocean voyager. [Music playing]

2 thoughts on “The Mutton Birds of Bass Strait (1956)

  1. The study of these birds including their habitat and numbers seemed to be of considerable importance to the Aust Gov't in 1956. Although they failed to mention that mutton birding is a traditional cultural practice of the original people, who were massacred hence populations largely diminished due to Genocide and colonization within 30yrs of "settlement" and typically the major cause of decrease in numbers of these birds was due to "settlement" ie introduced species and loss of habitat. Pity these same concerns weren't for the original people who had inhabited this land for 60,000yrs and at this particular point in time '56' they were not even entitled to vote, or part of an invaders constitution "The White Australia Policy" shame aus shame!!!!! Btw still NOT interested in your constitution REGURGITATE your control and law it's pathetic just another imposed biased, one sided, right wing capilist attempt at justifying theft and GENOCIDE!!!!!!!

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