Newsletter of the AUSTRALIAN PLATYPUS CONSERVANCY
ISSUE 32 - February 2006
It’s always nice to catch up with old friends, including the
four-legged variety. Late last year, Conservancy researchers were pleased to
renew their acquaintance with two platypus that have been periodically entering
survey nets for nearly a decade, as part of the Melbourne Water urban platypus
program.
Male 636D42 was marked with a uniquely coded Trovan microchip in
February 1996, in the course of the first live-trapping survey ever undertaken
along Monbulk Creek, in Melbourne’s southeastern suburbs. He was identified to be a subadult (or
second-year) animal, weighed 1830 grams, and was in above average condition
based on the amount of fat deposited in his tail.
636D42 has since been captured 7 times—in June 1997, February 1998,
December 2000, December 2001, August 2003, October 2004 and November 2005–at
sites distributed along 12-13 km of stream channel.
His weight has ranged from 1825 to 2120 grams, with the highest
weights achieved in spring (August–November). There is no evidence that he has
grown appreciably since he was first encountered (at the age of about 16-17
months): measurements of head-tail length have differed by less than 5% over the
period, in line with variation related simply to his posture and orientation.
In fact, the only really notable change to his appearance over time
has involved the venom-delivering spurs located on his inner hind legs. When first examined, these were about 17
millimetres long and very sharply pointed.
Over the next 7 years, each spur gradually became blunter. Then, in October 2004, 636D42’s left spur
was found to have vanished entirely—snapped off at the base!
Male 971857 was first recorded along the middle reaches of Monbulk
Creek in March 1996. He was a recently
weaned juvenile, weighed just 1000 grams and was otherwise rated as thin. Happily, he managed to live through the
following winter and has since been recaptured 9 times—in January and June 1997,
January and September 1998, November 2000, October 2002, August 2003, October
2004 and November 2005—at sites located along 7-8 kilometres of stream.
971857’s weight increased by more than 50% between the date he was
first captured and when he was next encountered as a subadult, 10 months
later. His head-body length also
increased in the interim, by around 10%.
Since becoming a fully mature adult, his weight has fluctuated between
1705 and 1975 grams, with the highest value recorded in August 2003—the same
month when 636D42 attained his maximum known weight.
The fact that platypus sometimes survive for a decade or more in
suburban habitats is a tribute to the species’ resilience and
adaptability. Given that male platypus
are expected for a variety of reasons to die at a younger age than females, the
longevity of 636D42 and 971857 is an extremely interesting as well as pleasing
new finding.
In a practical sense, it means that platypus do not need to
reproduce successfully every year for populations to persist through time. However, it also implies that the presence
of platypus in waterways that have been badly degraded by drought or other
impacts should not in itself be grounds for complacency—if conditions are
consistently too poor for young animals to be recruited, the population will
eventually disappear.
THE QUESTIONABLE PLATYPUS
APC staff answer platypus-related questions nearly every day, after
people get in touch with us by phone, after knocking on our front door at
Toorourrong Reservoir Park, or via the internet. Some questions asked by overseas researchers are quite technical
and in some cases impossible to answer—the answer simply isn’t known. We also get asked a lot of questions by
students of all ages and their teachers, property owners and other persons
interested in conserving the species, and a diverse spectrum of individuals
from around the world who may be best described as “platypus enthusiasts”.
Here are some repeatedly asked or unusual questions along with
their answers, formulated to the best of our current knowledge:
Are platypus good to eat?
We don’t know of any person in recent times who has tried dining on
a platypus. According to Harry Burrell
(a keen naturalist and archetypal platypus enthusiast who wrote a book about
the species in the 1920’s), a letter published in the Sydney Daily Telegraph
in 1923 reported that some miners ate one and found it to be “a somewhat oily
dish, with a taste between those of red herring and wild duck”. Burrell also quotes the remarks provided by
R. Semon, published in 1894, that aboriginal people residing near the Burnett
River did not include the platypus in their diet because the meat had “an
objectionable smell”, presumably related to scent glands found at the base of
the platypus’s neck.
Can platypus jump?
This question is mainly raised by American school students in grade
5, apparently after being taught that “elephants are the only land mammal that
cannot jump”. While not wishing to
undermine the efforts of American educators, we feel quite confident that
platypus are at least as inept as elephants when it comes to launching
themselves up off the ground. This
generalisation is based in part on our understanding of how the platypus skeleton
is constructed: the animal’s limbs extend
horizontally from the body, so the chest and abdomen are actually in contact
with the ground at low speed.
Furthermore, the joints and ligaments which bind the platypus’s legs to
its body are designed to facilitate rotational (as opposed to back and forth)
limb movements: the platypus can swim and dig very efficiently, but is poorly
equipped by nature to compete in any sort of track or field event.
Can platypus climb?
The platypus’s front foot is highly
specialised, with a broad band of webbing extending well beyond the end of the
toes to assist swimming. In turn, this
tends to preclude any ability to grasp or manipulate objects such as tree
branches. However, platypus are
exceptionally inventive and determined creatures when it comes to scaling surfaces
that stand in their path. They can
scramble up steep rocky banks with aplomb, and have also been known to try to
escape from the confines of a galvanised metal tank by wedging themselves
between the side of the tank and a vertical water pipe and propelling
themselves upwards like a giant inchworm.
Can platypus be kept as pets?
Platypus are notoriously difficult animals to keep in
captivity. They eat a lot of food (in
the order of 20% of their body mass each day) and are also quite picky about what
they eat, preferring live aquatic macro-invertebrates such as insect larvae,
worms and crayfish. Feeding and
exercise tanks need to be as roomy as possible (after all, wild platypus have
home ranges extending for a kilometre or more) and the water must be kept clean
and fresh by appropriate use of automatic filters or being changed each
day. Adult males in particular can be
dangerous animals to handle—while the venom delivered by platypus spurs is not
considered to be life-threatening to humans, it can cause excruciating
pain. Sensibly, there is no place in
Australia where a platypus can be legally maintained as a pet, nor any legal
options for exporting the animals as pets overseas.
Did You Know That....
Platypus occur along the east
coast of mainland Australia to about the latitude of Cooktown in
Queensland. It has been suggested that
the absence of platypus from rivers located farther north in Cape York and
those draining into the Gulf of Carpentaria may be due to predation by
crocodiles.
AUSTRALIAN GEOGRAPHIC SUPPORTS NEW CONSERVATION LEAFLET
In many ways, platypus make ideal neighbours: they don’t trespass
on land, interfere with livestock or cause any other sort of management
problem, make any appreciable noise, or overpopulate their habitat.
People almost always enjoy the fact that platypus live in local
water bodies, in part because this says something quite positive about the
quality of the area as a place for people to live as well as wildlife. So what can people do both to protect existing
platypus populations and encourage the animals to recolonise places where
platypus no longer occur?
Australian Geographic will be holding a special fundraiser from
April to June 2006 to raise money for a
new APC leaflet highlighting some of the practical measures that can be
undertaken to assist platypus conservation.
The leaflet will be designed to be of interest to a wide audience,
from professional waterway managers to landowners, conservation volunteers and
students.
It will focus particularly on the issue of litter, which continues
to be a major problem for platypus welfare both in urban and rural areas. A range of other platypus conservation
issues will also be discussed, including the vital importance of conserving
water on the world’s driest inhabited continent, and suggested ways to improve
platypus habitat.
Special platypus stickers can be purchased at Australian Geographic
shops during the fundraising period and donations can also be made at all AG
stores or directly to the Society.
AUSTRALIAN GEOGRAPHIC LECTURE
The APC’s platypus research in suburban waterways will be featured
in an article titled “Wild Melbourne” in the forthcoming April-June issue of Australian
Geographic magazine.
Coinciding with this article and the Australian Geographic platypus
conservation fundraiser, the Conservancy is presenting an illustrated lecture
about Melbourne’s platypus on behalf of the Society.
The talk will be held at the Melbourne Museum’s The Age
Theatre on Tuesday, 23 May at 7.30 in the evening.
For more details, contact Australian Geographic, PO Box 321, Terrey
Hills, NSW 2084.
FORTHCOMING APC PUBLIC TALKS IN 2006
Sunday 23 April at 2.30 pm. Edendale Community Farm, North Eltham
(on platypus conservation as part of the Shire of Nillumbik environmental
workshop series).
Wednesday 7 June at 7.30 pm. South Warrandyte Hall (on Australian
water-rats as part of the City of Manningham environment series).
Other talks being planned for the winter of 2006 will be held at
Echuca (on platypus) and Benalla (on Australian water-rats).
For additional details, please contact the Conservancy.
SPONSOR A PLATYPUS
Four platypus—Double Trouble, Lucky, Little Notch and Magellan—can
be sponsored to assist the APC’s research and conservation programs.
The cost of sponsorship (in Aus. $) is as follows:
1 platypus only: $10.00; 2 platypus: $18.00;
3 platypus: $25.00; All
four: $30.00.
Further information about the four featured platypus and sponsorship application forms can be obtained by visiting the APC website or by contacting the Conservancy directly.