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 17 Winter 2000
PLATYPUS PREFER
GUM TREES
Radio-tracking studies undertaken
in 1998 by APC researchers in Melbourne's southeastern suburbs (funded as
part of Melbourne Water's Urban Platypus program) indicated that platypus
tend to avoid using stream segments dominated by willows, at least in summer.
These findings have now been
confirmed by a study of how habitat attributes affect platypus feeding behaviour
along Running Creek, a small stream located in the upper Diamond Creek catchment,
northeast of the Melbourne city centre.
After monitoring the nocturnal
movements of five radio-tagged platypus in late summer and early autumn,
APC biologists determined that platypus activity was negatively related to
the number of willows found on the banks. Conversely, platypus activity
was positively related to the number of native trees (gum trees and wattles)
growing along the channel.
Each 25-metre section of waterway
in the part of Running Creek used by radio-tagged platypus supported on
average 11 medium-to-large trees growing within 8 metres of the water, of
which 82% were eucalypts or wattles and 8% were willows. By comparison,
the same amount of bank in the area not used by platypus supported on average fewer
than 5 medium-to-large trees, of which only 21% were native trees and 70%
were willows.
Differences in water quality
were also apparent when a site dominated by gum trees was compared with
a site dominated by willows. Notably, only about one-quarter as much oxygen
was dissolved on average in the water under willows as compared to that
under eucalypts-a level low enough to stress many aquatic insects (which
in turn comprise the main platypus food supply).
Similarly, research in Tasmania
has found that streamside willows are associated with very low dissolved
oxygen levels in summer, possibly due to high rates of bacterial growth within
the dense root mats which typically invade the channel under these trees.
The very tough, fibrous nature
of willow root mats are also likely to physically impede the efforts of
any platypus interested in sampling invertebrates at sites where willows
are abundant.
The significant negative relationship
between platypus feeding activity and willows along Running Creek suggests
that the size of the local platypus population may well increase if sizeable
tracts of willow are progressively replaced by native vegetation.
Happily, as part of an ambitious
catchment rehabilitation program for Diamond Creek and its tributaries,
planning is now well underway for a series of stream improvement works to
be undertaken along Running Creek.
The works-to be carried out
by Melbourne Water in co-operation with local landowners and Landcare groups-will
include removing willows, fencing stream banks to control access by livestock,
and replanting the stream corridor with appropriate indigenous trees and
understorey species.
Incorporating reliable information
on platypus ecology into these and related work programs will help to ensure
that they are as platypus-friendly as possible. As well, collecting benchmark
ecological data before
works are undertaken
should make it
possible to assess the actual
contribution made by rehabilitation protocols to improving the health of
aquatic wildlife habitats.
BARWON PLATYPUS STUDY
A Conservancy research program
in the Wimmera River catchment has shown that platypus currently reside
along a relatively small proportion of the waterways in this important wool-growing
region.
It seems highly likely that
platypus numbers have also declined in other catchments where natural habitat
conditions have been modified by agricultural practices.
The APC plans to continue its
work in the Wimmera, in order to monitor the status and health of platypus
in the region. However, it is essential that new studies also be commenced
to examine how platypus are faring in other farming environments.
One such project, starting
in spring 2000, will involve a series of surveys along the Barwon River,
which flows from the Otway Ranges to Geelong in south-central Victoria.
This waterway has been substantially modified since European settlement
and its biodiversity values continue to be under enormous pressure from
the combined impacts of rural and urban land use. In particular, salinity
levels have risen dramatically as a result of man-made drainage schemes
in the catchment.
Live-trapping surveys by the
APC, undertaken in collaboration with the Corangamite Catchment Management
Authority, will provide information on the abundance and distribution of
platypus in the system. Reflecting the value of platypus as an indicator
species, the research results will also make an important contribution to
the Barwon River Health Strategy which is being formulated to address water
and land management problems.
The surveys (using local volunteers)
will be complemented by a local "Platypus Watch" campaign to encourage reports
of sightings, as well as public talks by the APC to raise awareness of platypus
conservation issues.
In addition to the Wimmera,
the Hopkins catchmentand
now the Barwon, the status of the platypus in other farming areas will be
investigated as further funding becomes available. As well, there is a
need to determine how may platypus occur in relatively undisturbed habitats
(e.g. national parks and forest reserves) to ascertain whether the species
can be truly regarded as "safe" in such environments.
ONE GOOD INTERN DESERVES
ANOTHER
The platypus is a very difficult
species to study in the wild because of its mainly nocturnal and aquatic
lifestyle. As a result, few biologists are committed to major research projects
involving the ecology of the species
To help address the shortage
of platypus biologists, the Conservancy provides training opportunities
which encourage students and recent graduates to experience the challenges
of platypus fieldwork.
The latest recruit to this
program is Melanie Swinnerton, who graduated in zoology from the Australian
National University at the end of 1999. During the course of her undergraduate
studies, Melanie worked very successfully as a volunteer with APC research
teams and accordingly was an ideal candidate to become the Conservancy's
second Mazda Foundation Trainee at the beginning of this year.
As a trainee, Melanie mastered
the intricacies of a variety of fieldwork techniques, through involvement
in platypus research projects in both rural and urban areas.
She has now progressed to an
APC Internship (supported by the Ross Trust) which will see her take substantial
responsibility for one of the Australian Platypus Conservancy's many projects.
NATIONAL GEOGRAPHIC PLATYPUS
The April 2000 edition of National Geographic magazine carried an 11-page colour
feature on platypus, the result of a successful collaboration between APC
Conservation Biologist Melody Serena and American photographer David Doubilet.
Widely regarded as one of the
world's best underwater photographers, Doubilet was faced with special challenges
in getting shots of the platypus in its natural habitat. In comparison
to the sharks, seals and other spectacular marine creatures which are the
usual focus of David's art, the small and cryptic platypus comprised a much
more elusive subject.
However, after working with
an APC field team for several weeks on Kangaroo Island and around Melbourne,
and lying on the bottom of a rocky creek bed for many hours in a wetsuit,
some spectacular photographs of the platypus in its underwater world were
obtained.
One image in particular, of
a platypus twisting its way through swirling water, is an evocative reminder
of the fact that this species can be traced through the fossil record to
the time of the dinosaurs.
The accompanying text has been
designed to give the magazine's 40 million readers an overview of the unusual
biological features and conservation status of this remarkable animal.
Dr Serena is the recipient
of a National Geographic Society Research Grant.
RECENT PUBLICATIONS BY
APC STAFF
The following articles have
recently been published by APC staff and associates:
De-La-Warr, M. and Serena,
M. (1999). Observations
of platypus Ornithorhynchus
anatinus mating behaviour. The Victorian Naturalist 116, 172-174.
Serena, M. (2000). Duck-billed platypus: Australia's
urban oddity. National
Geographic, vol. 197,
no. 4, pp. 118-129.
Serena, M., Williams, G.A.,
Thomas, J.L. and Worley, M. (1999). Effect of a flood retarding basin culvert on movements
by platypus Ornithorhynchus
anatinus. The Victorian Naturalist 116, 54-57.
Williams, G. (1999). Our flagship for freshwater
conservation. Chain
Reaction, Winter 1999,
pp. 18-19.
Williams, G. (2000). The urban platypus. Greenhouse Living, Winter 2000, pp. 10-13.
Williams, G. (2000). Unravelling the platypus mystery.
Wildlife Australia, Winter 2000, pp. 2-5.
Worley, M. and Serena, M. (2000). Platypus need streamside vegetation.
Victorian Landcare
and Catchment Management, issue 16, pp. 12-13.
Worley, M. and Serena, M. (2000). Protecting the platypus. Park Watch, no. 201, pp. 5-6.
LIVING WITH PLATYPUS
REPRINTED
The Conservancy's Living With Platypus booklet has recently been reprinted,
following an enthusiastic response from Landcare and other community conservation
groups, government management agencies, and schools.
The 40-page publication summarises
much of what is currently known about the platypus and offers practical
advice on measures that can be taken to assist platypus conservation in
urban and rural waterways.
Copies of the booklet can be
obtained from the Conservancy.
Friends of the Platypus
receive a free copy
when they join the organisation or renew their membership.
Did You Know That....
Like most diving
mammals, the platypus has blood that is rich in oxygen-carrying haemoglobin
and red cells. The platypus can also reduce its need for oxygen underwater-by
lowering its heart rate from more than 200 beats per minute to less than 10
beats per minute.