Ripples is the
quartlerly newsletter of the Australian Platypus Conservancy. It provides
updates on research in progress and other APC news. Members of Friends of the
Platypus automatically receive each edition
of Ripples.
Ripples Newsletter of the AUSTRALIAN PLATYPUS CONSERVANCY
Issue 19 Winter 2001
PLATYPUS IN THE BARWON
The Barwon River arises on the slopes
of the Otway and Great Dividing Ranges in southern Victoria and flows through
the city of Geelong before emptying into Bass Strait at Barwon Heads. Graziers
began settling this catchment shortly after Europeans arrived in Victoria
in 1835. Today, much of the basin continues to be devoted to the production
of sheep, dairy and beef cattle, and a variety of grains and other crops.
Earlier this year, the APC undertook
platypus surveys along four representative sections of the Barwon (each measuring
7.5-20 km in length), distributed between the town of Birregurra and the
outskirts of Geelong. The work was commissioned by the Corangamite Catchment
Management Authority, and aimed to provide information needed to develop
a River Health Strategy for the area. To sample platypus effectively, nets
were monitored carefully throughout the night at four to eight sites within
each survey area. After being measured and micro-chipped (for permanent identification),
animals were released back to the wild at the exact site where they had
been captured.
The good news was that reasonable numbers
of platypus were recorded in each of the four survey areas. Furthermore,
a juvenile male was encountered in February at a site located near the outskirts
of Greater Geelong, suggesting that breeding occurs successfully to at least
the upstream edge of the city. On a less positive note, platypus were not
captured at more than one-third of the sites where nets were set, with fewer
animals apparently living both in the uppermost survey area (around Birregurra)
and the lowermost area (between Fyansford and Gnarwarre) as compared to
the river's middle reaches near Winchelsea and Inverleigh.
There is no way to know precisely how
many platypus lived along the Barwon in the early 1800's. However, a number
of factors are likely to have reduced the river's productivity in the past
150 years, including a decline in the numbers of native gum trees and shrubs
growing on the banks, the proliferation of gorse and willows, increased
rates of bank and channel erosion, inputs of salt and other pollutants from
a variety of sources, and reduced summer flows.
In addition, there is good reason to
believe that platypus populations along the Barwon River are being damaged
by encounters with rubbish left along the waterway-three of the 32 animals
captured in January and February had deep cuts or badly worn areas of fur
around the neck or chest, evidently due to their protracted entanglement in
loops of a tough material like nylon fishing line.
Fortunately, there is demonstrably strong
community support for conserving platypus along the Barwon, with about a
hundred local residents choosing to meet APC biologists at dawn after survey
sessions in order to learn more about the animals and see a platypus being
released back to the wild.
The Corangamite CMA is using the platypus
survey results (along with several other useful measures of riverine health)
to assess how well the Barwon is faring and decide which conservation actions
will most effectively address environmental concerns and strengthen the
river's habitat values.
As importantly, the baseline platypus
data generated by this year's survey program provides an objective benchmark
to help monitor the changing health of the Barwon River in the future.
Did You Know That....
About half
(30-60%) of a platypus's total body fat is stored in its tail. The fat
helps to insulate the tail (which is thinly furred as compared to the rest
of the body) when an animal is active in cold water.
Researchers
can get a good idea of how fat a platypus is by examining the shape of the
tail and gently squeezing its edges: the tail of a very fat animal will be
rounded in cross-section and cannot be bent inwards, while a thin platypus
will have a strap-like tail that can be folded along the midline.
FIRST PLATYPUS FOUND IN RUFFEY CREEK
Ruffey Creek is a highly urbanised waterway
flowing through the eastern Melbourne suburbs of Doncaster and Lower Templestowe.
APC biologists were not particularly
surprised to find that no platypus were recorded along Ruffey Creek in 1996,
when surveys were first carried out as part of Melbourne Water's Urban Platypus
Program. The scope of habitat change along the creek was underscored by the
presence of a stolen car at one survey site, driven down the stream banks
on the night before nets were set.
In May 2001, researchers again set nets
along Ruffey Creek as part of the routine platypus population monitoring
which takes place along Melbourne's waterways.
This time, they were delighted to encounter
no fewer than three animals: one adult (or possibly subadult) female was
captured about 50 metres above the point where Ruffey Creek joins the Yarra
River, while two males (one adult and one juvenile) were recorded at a site
located about 1.3 kilometres farther upstream. The adult male was travelling
downstream when he entered the net, several hours after midnight-suggesting
that he may have moved a kilometre or more before he was caught.
Ruffey Creek is the third waterway in
the Melbourne metropolitan region (along with Diamond Creek and Mullum Mullum
Creek) where platypus appear to have expanded their range in the last few
years.
Importantly, in all three cases platypus
have been recorded for the first time in or near sections of creek where
extensive channel stabilisation works-mainly undertaken to control erosion
caused by storm water runoff from roofs and other hard surfaces-were implemented
in the previous year by Melbourne Water.
This pattern suggests that there is
a causal link between stabilisation works and improved stream productivity,
which in turn promotes increased usage by platypus.
It is not surprising that platypus are
quite a sensitive indicator of changing conditions along a waterway, given
that they depend on the presence of large populations of smaller aquatic
organisms (such as insects, worms, snails, shrimps and yabbies) to serve
as their dinner.
Because platypus are highly mobile animals-quite
capable of moving several kilometres in a single night as they search for
food or (in the case of adult males) mates-it also makes sense that they
quickly occupy any vacant habitat that becomes available.
NEW PLATYPUS BOOK
Ann Moyal, member of Friends of the Platypus andawell-known historian of Australian science, has written a new
book: "Platypus-the Extraordinary Story of How a Curious Creature Baffled
the World".
It tells the fascinating story of how
scientists gradually unraveled some of the mysteries surrounding this most
enigmatic of animal species.
Published by Allen & Unwin, the book
is widely available from good bookshops.
THANKS TO VOLUNTEERS
Every type of job has its good points
and bad points.
Those aspiring to undertake platypus
field work can look forward to a lot of long nights, murky water, tangled
nets, and slippery mud.
On the other hand, there are few things
more interesting than learning to see the world from the perspective of
another species; the dawns are beautiful; and it is very special to meet
the huge range of people who care about Australia's wildlife in general
and the platypus in particular.
More than a hundred such individuals
have put their feelings into practice over the past nine months by helping
out as volunteers with APC live-trapping surveys.
A look at the rosters reveals that about
half of these volunteers either belong to Friends of the Platypus or live in the district where the work was being
undertaken.
About a third were secondary students,
tertiary students, or young people engaged in special environmental training
programs.
As well, a large number of volunteers
were drawn from the ranks of management agencies or local government, including
Melbourne Water, VicRoads, and several Catchment Management Authorities
and city councils.
Besides providing practical (and much
appreciated) assistance with setting and checking nets, we hope that the
experience of working on behalf of platypus conservation has given APC volunteers
a better understanding of these very special animals.
SPONSOR A PLATYPUS
Since 1995, the Friends of the Platypus organisation has provided the main avenue for
community support of the APC's work. Details of how to join the Friends can be found on page 4. However, there has also been strong
interest from people wishing to sponsor an individual platypus identified
through the Conservancy's research and conservation programs. Accordingly,
the APC has now established a platypus sponsorship scheme which initially
involves four different animals:
Lucky was a small juvenile when found with a metal
band stuck around his neck. Fortunately, APC researchers were able to cut
through and remove this item, which would have eventually strangled him.
Later surveys have confirmed him alive and well after his lucky escape.
Little Notch is a female platypus recognisable from the small
notch in her upper bill, possibly caused by the sharp pincers of a freshwater
crayfish. She is one of several animals who have been handled many times
during ongoing research along Jack's Creek, near the APC's base at Toorourrong
Reservoir Park.
Double Trouble was rescued as a juvenile from the jaws of a
dog. Unfortunately, the rescuer then made a common mistake-placing the tiny
animal in a tub of water for the night. When finally picked up by the APC,
the young platypus was so cold and exhausted that she could barely move.
However, with some expert care, she recovered completely and was eventually
released back to the wild.
Magellan created a "world record" distance for platypus
travel. APC surveys in the Wimmera found that this young animal had moved
over 45 kilometres in search of a territory to call his own.
For each platypus sponsored you will
receive: * A certificate bearing your name (or name
of a person you designate, if intended as a gift), a scanned picture and
description of the platypus, and information about the area in which it lives. * A blank platypus greetings card.