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 16 Autumn 2000
CONSERVING THE PLATYPUS
IN RURAL WATERWAYS
Describing a species' habitat
requirements is one of the most challenging tasks faced by modern conservation
biologists.
Unfortunately, we cannot expect
animals to provide us with a list of desirable features in their environment,
nor can we read their minds.
Alternatively, we can map the distribution of a species in a particular
area and then find out whether habitat attributes vary consistently in relation
to the animals' population density.
To assist platypus conservation
in agricultural areas, APC staff recently completed a study of the species'
habitat relationships along the Wimmera River in western Victoria. Following
extensive live-trapping surveys, bank and channel characteristics were measured in an area
known to support reasonable numbers of platypus (between Crowlands and Elmhurst)
as well as a neighbouring area supporting few or no platypus (downstream of
Crowlands).
Interestingly, several habitat
features showed a very strong positive association with platypus, including
the number of medium-to-large trees (mainly river red gums Eucalyptus camaldulensis) growing near the channel, the amount
of leafy vegetation overhanging the bank, and the amount of dead wood (logs
and large branches) lying in the water.
As well, some habitat features
were negatively associated with platypus, including the presence of sandy
or gravelly beaches along the edge of the channel - an indicator of high
rates of erosion farther upstream in the catchment.
In general, the habitat attributes
that appear to be good for platypus along the Wimmera are also known to
be good for aquatic insects and other freshwater invertebrates such as yabbies.
For example, large trees provide shade which helps to keep the water cool
in summer, thereby maintaining reasonably high levels of dissolved oxygen.
Organic materials such as dead leaves and branches provide places for invertebrates
to feed and shelter from sources of disturbance, including strong flows.
By controlling erosion along the banks, trees and smaller plants also limit
inputs of mobile sediments which create poor living conditions for most
aquatic organisms.
These relationships make sense
given that the platypus is a top predator which mainly feeds on bottom-dwelling
insects, worms, snails, yabbies and freshwater shrimp.
Because platypus can only thrive
as part of a productive aquatic community, it is not surprising that the
animals are a valuable indicator of the biological integrity of freshwater
systems.
The fact that so many of the
habitat factors that are positively linked to platypus along the Wimmera
relate to trees and other plants growing on the banks also highlights the
key role played by good land management in stream and river health.
In short, even though we can't
read their minds, the message provided by platypus couldn't be clearer.
By working together in the Wimmera (and other country catchments) to ensure
that stream and river margins are managed sustainably, farmers will contribute
enormously both to waterway conservation and platypus survival.
HOW TO HELP A LOST PLATYPUS
Platypus breed only in late
winter and spring, incubating a clutch of 1-3 eggs in an underground nest
for a period of 10-11 days.
The young first emerge from
their natal burrow 3-4 months later, in the period from January to April.
At this age they are well-furred and able to swim, but weigh only about half
as much as adults. Like human infants, they also appear to be both curious
and naive about the world. As a result, it is by no means uncommon for small
juvenile platypus to end up in all sorts of inappropriate places - suburban
gardens, ploughed grain fields, chlorinated public swimming pools, and the
middle of paved city streets. As well, grown platypus are sometimes found
wandering long distances from waterways when they are forced to leave an
area because of population pressure or catastrophic changes to their habitat
(for example, when a river dries up during a drought).
Confronted by a platypus in
one's own backyard, perhaps a kilometre or more from the nearest stream, what's
the best thing to do?
Firstly, although the platypus
is not a naturally aggressive animal, caution is warranted whenever picking
up an individual of unknown age and sex. This reflects the presence of
sharp poisonous spurs on the heels of adult males. The spurs are about
1.5 centimetres long and curved like a dog's canine tooth, and while the
poison is not considered to be life-threatening to humans, it can cause
excruciating pain and spectacular swelling for the best part of a week.
Hence, until it is established that a given platypus is definitely not
equipped with such spurs, it is highly inadvisable to hold or carry the
animal by supporting it from below. As a safe alternative, lift the platypus
by gripping it firmly around the middle or end of its tail (but not the
base of the tail, which a male can reach with his spurs).
Secondly, when selecting a
container to temporarily hold a platypus, be aware that these animals are
gifted escape artists. Though it may not look particularly agile, the average
platypus is both very strong for its size and exceptionally good at squeezing
through holes, gaps or cracks. As a temporary measure, the animals may
be successfully confined for a short time in a sturdy cardboard box with
a reasonably strong cover or lid.
If circumstances require that
a platypus is held overnight before being released back to the wild or taken
to a veterinarian, consider confining the animal within an old cotton pillow
case, knotting a piece of twine tightly around the opening. Make sure that
the animal has enough room inside to stretch out and move around a bit,
and place the pillow case and its occupant in a box in a relatively cool
(less than 30o C), quiet location where it won't
be disturbed by curious pets or children. Because a platypus enters the
water mainly to feed, it is generally wrong to force an animal to spend the
night in a half-filled bath tub, unless a lot of food is provided in the form
of live aquatic insects to replace the energy used while swimming! Even
then, the animal will also need to be given a dry place to groom itself and
rest.
Thirdly, if there is no reason
to believe that a platypus found in an unusual place is injured, the animal
should be returned to a suitable nearby section of waterway as soon as possible.
Because platypus are wild animals with specialised living requirements,
it is inappropriate (and illegal) to try to keep one as a pet for even a
short period of time - the animal is highly unlikely to survive the experience.
Especially in drought years,
a platypus may be forced to leave its territory as environmental conditions
deteriorate. If the stream or river closest to where a platypus is found
appears to be nearly dry, it would probably be best to release the animal
along a different, reliably flowing waterway within the same river system
- so the animal can potentially find its way home when conditions improve.
Did You Know That....
Based on research undertaken
by Dr Tom Grant, the oldest platypus recorded to date in the wild lived to
the age of 16 years. More studies are needed to determine how long individuals
typically survive, though estimates of about 4-5 years for males and 6-8 years
for females are not unreasonable.