| The bounty schemes:
Following the introduction of commercial sheep farming into Tasmania in
the 1820s, the thylacine was unfairly perceived as a vicious sheep killer,
and relentlessly persecuted through a series of government and private
bounty schemes. The government bounty scheme ran from 1888 until
its termination in 1908, although bounty payments continued to be paid
until 1909. The bounty scheme of the Van Diemen's Land Company (VDLC)
ran from 1830 until its termination in 1914. Numerous local bounty
schemes ran in concert with the government bounty. Over the 20-year
period that the government bounty was in force, some 2,184 thylacines were
killed. Over the same period, 81 thylacines were killed at the VDLC
property at Woolnorth, in the far northwest of Tasmania. Totals for
the various local bounty schemes do not exist, but a conservative estimate
of around 200+ kills would be a fair estimate. |
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Thylacines presented
for government bounty annually 1888-1909
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Source: After Guiler
(1961, p. 208).
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| Click
graph icon to view data: |
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| Both the government
bounty records and those of the VDLC property at Woolnorth provide evidence
of a rapid population decline. With specific reference to the government
bounty, two distinct phases are apparent:
Stable cull (Phase
A-B):
Between 1888 and 1905,
the total number of thylacines submitted for bounty was 1954, with a mean
of 122.
Population collapse
(Phase B-C):
Between 1905 and 1908/9,
the total number of thylacines submitted for bounty was 230, with a mean
of 46, indicative of a sudden population collapse.
Total A-C (N = 2184
mean = 104) |
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|
Thylacines presented
for bounty at Woolnorth 1888-1914
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|
Source: After Guiler
(1961, p. 209).
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| Click
graph icon to view data: |
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Sleightholme & Campbell (2015) assert: "If we accept Guiler's population
estimates, the annual bounty yield prior to 1905 appears to have been sustainable
at around 4-5% of the population, and in the absence of any other factors,
was unlikely to have pushed the thylacine towards extinction".
Guiler (1985, p. 26) notes:
"The catch of thylacines
under the bounty scheme was steady at about 100 per annum until 1905 when
the number fell dramatically, reaching zero in 1910. The Woolnorth
catches declined in the same fashion. This final decline, which was
very rapid and occurred all over the state at about the same time, is not
typical for a species that has been hunted to extinction. If the
thylacine had been hunted to extinction, it is my view that it would be
logical to expect the animal to disappear first from the places they had
been most vigorously hunted since early settlement, but this did not take
place."
Disease:
Miller et al. (2009), in their pioneering work on the thylacine genome,
demonstrated that ultra-low levels of genetic diversity existed within
the thylacine population. Sleightholme & Campbell (2015) state:
"This
is consistent with a founder effect, and would have impacted on the thylacine's
ability to resist disease". As a general rule of thumb, the greater
the genetic diversity within a population, the greater that population's
ability to resist disease.
An epizootic
disease, often cited in the literature as being mange or distemper-like,
decimated thylacine and other dasyuromorphian
marsupial numbers in the last decade of the nineteenth and first decade
of the twentieth century, persisting into the late 1920s. From historical
accounts, it appears to have taken the disease several years to spread
from east to west coast populations.
The Mercury newspaper
of the 19th October 1934 (p. 11) notes: "Disease, a type of mange, cleared
the tiger. There was not a specimen of this destructive animal left
on the eastern side of the railway, nor on the banks of the Derwent or
Tamar".
Fred Burbury (1953)
wrote:
"About 1910 the thylacines
seemed to disappear, also the indigenous cats, native cat and tiger cat.
I know a form of distemper killed the cats but I have no practical evidence
that a similar cause killed the tigers. The real fact was, the destruction
of sheep ceased, and others with me thought it was because of distemper".
In the Advocate newspaper
dated the 10th February 1937 (p. 12), Mr. Alfred W. Burbury of the Animals
and Birds Protection Board made the following comment when referring to
the sudden collapse in thylacine numbers:
"If the animal was
extinct, it was through disease. The last few caught some years ago
were suffering from some form of mange, which also had been responsible
for the destruction of many native cats". |
