AMAZING TURTLE
FACTS
They suck up water
through their bottoms, squirt foul smells and, despite their name,
live happily in raw sewage. Australian freshwater turtles are tough,
resilient creatures armed with a battery of defences which enable
them to take drought, pollution and even car accidents in their very
slow stride. Abbie Thomas meets a true Aussie survivor.
Turtles are far tougher than they look. Image: Arthur Georges.
Australian freshwater turtles are very endearing - zappily cute when
tiny, slothfully charming when full grown - and adored by thousands
of children and adults who keep them as pets both in their native
land and around the world.
Yet these seemingly snoozy animals - many of whom have been run over
while venturing out in the rain showers at this time of the year -
have another side to them: tough, resilient creatures armed with a
battery of defences which enable them to take drought, pollution and
even car accidents in their very slow stride.
Even the worst of Australian droughts won't stop this animal from
its steady existence: when the water dries up, it shuts down almost
entirely, breathing perhaps once every two or three days, slowing
its growth to one millimetre in a decade, and cutting back on anything
that requires effort - including sex.
Click on Your
Favourite Cuddly Aussie
The 'Stinker'
The most common of Australia's 25 species of turtle - and the most
often seen in the wild in eastern Australia - is the long-necked or
snake-necked turtle Chelodina longicollis. The long-neck, or 'stinker'
as it is often called for reasons which will become obvious, is something
of a passion for Canberra University's Professor Arthur Georges. "You
see people picking them up off the side of the road after a big rain.
They drive about 40m, then suddenly pull up and the turtle gets tossed
out of the car," he laughs.
Long-necks sport a carpet of brilliant green moss on their shell,
which may give them some camouflage.
Image: John Cann.
I have to admit something similar happened to me a few years ago,
while driving along the highway between Stroud and Wingham in eastern
NSW. I saw a turtle up ahead, standing right on the white line in
the middle of the road. Being a caring animal lover, I pulled over
and got out to move the reptile off the road. It was quite large -
about 20cm long - and felt heavy in my hands as I picked it up and
admired the bright green algae growing all over the shell. Then just
as I stepped off the road to place it carefully in the grass, it began
squirting some sort of liquid with an unbelievably obnoxious smell:
a gut-wrenching mixture somewhere between rotten cabbage and sewage.
I dropped the turtle quick smart but the smell stuck around for days.
Silent but deadly
Unlike their dull parents, baby long-necks are brilliant orange or
yellow. This colouration, combined with their strong odour, warns
predators not to take a bite. Image: Carol Browne, University of Sydney.
All Australian freshwater turtles have some type of scent or musk
gland, and the longneck is particularly well armed, sporting a gland
above each leg just where it emerges from the shell. The liquid contains
six different acids, not surprisingly producing a noxious brew - and
long-necks are the most pungent of all the turtles.
While the adult turtles actively squirt out this liquid, newly hatched
turtles just plain stink of it and experiments have shown that even
a starving eel will spit out a baby turtle. Yet after just a few weeks
in captivity, turtles usually cease to produce the odour, as they
settle down and relax in their new surroundings.
Long-necks are incredibly adaptable, and can be found paddling leisurely
along most of Australia's eastern rivers, as well as in many lakes
and human-made reservoirs. Thanks to a bag of turtle tricks, they
can survive in a wide range of climates, from areas like Cooma, NSW,
where air temperatures plunge below zero, to the western Queensland
town of Alpha, where summer temperatures shoot up above 40 degrees.
Where
to find turtles
Where: The long-neck can be found around river systems and
in dams, lakes and reservoirs throughout Queensland, New South
Wales, Victoria and South Australia.
Specifically:
The Murray-Darling system; many rivers in Victoria and New
South Wales and southern Queensland. Their range in Queensland
extends as far north as the Burdekin River, near Townsville,
and west to the Barcoo River.
|
Environment: Long-necks prefer slow moving rivers, swamps and
ponds, where food is easier to catch. The geographic isolation
brought about by waterfalls and other natural barriers has produced
intriguing variations in colour and shell size. For example,
populations west of the Great Dividing Range tend to have broad
shells, while those to the east are more oval or oblong, leading
some to suggest they are subspecies. |
On Walkabout
One trick which intrigues Arthur Georges is the turtle's habit of
suddenly leaving its pool or river and going walkabout, sometimes
travelling 10 kilometres or more.
This migration often occurs en masse, much to the amazement and consternation
of local people. In 2003, residents rushed to rescue turtles fleeing
Dowse Lagoon, Sandgate in inner city Brisbane which - succumbing to
a prolonged drought - had almost dried up for the first time in 50
years. As water levels plunged, turtles abandoned the sticky mud and
began trying to cross busy streets surrounding the wetland in an attempt
to find water. About 500 turtles were rescued and relocated to other
waterways around the city. Arthur Georges says turtles have also been
on the march around the eastern states of Australia, as rains return
to some drought-affected areas.
Long-neck on the move from its dune lake to a nearby swamp. Image:
Arthur Georges.
Turtles moving about are nothing new. In the early 1990s in Victoria,
thousands of migrating long-necks climbed a rail embankment in Victoria
and were killed in their hundreds by passing trains as they tried
to cross the tracks.
Sydney-based turtle expert John Cann describes another incident, on
the Hawkesbury River several decades ago, when local people were amazed
to see hundreds of turtles crossing a road between the towns of St
Albans and Sunnyvale.
Migration is clearly a risky business, where turtles forsake the safety
of their regular haunts to travel long distances and expose themselves
to the danger of injury or even death. Yes, it is risky, acknowledges
Arthur Georges, who has been studying mass migration of turtles in
Jervis Bay, NSW, but there can be big payoffs for the intrepid terrapin.
The tough life
The life of long-neck turtles living in two lakes tucked behind sand
dunes was studied by Arthur Georges. The turtles scraped by eating
small animals, such as plankton, water-living insect larvae or small
creatures which fall on the water. It's a lean existence - dune lakes
tend to be low in nutrients (because they are on sand) and consequently
support little biodiversity compared to other water bodies.
Contaminants in urban water ways may be accumulated by the mother
turtle and passed on to her eggs, thinning the shells and affecting
the health of hatchlings. Image: Carol Browne, University of Sydney.
During periods of extended drought, Arthur Georges found that turtles
living in these lakes lost a great deal of weight and many even stopped
breeding.
But it turned out they were just hanging out for better times. As
soon as the rains came, the turtles left their lakes and undertook
the hazardous journey - navigating by the sun, landmarks and their
sense of smell and strolling up to 1km/day - to nearby swamps which
had just filled with rain. These swamps are ephemeral, filling only
once every few years after big rains. But while they are not a permanent
source of water, the swamps are high in nutrients, which are released
from the sediments during dry weather and then explode with life in
the rains. The swamps offer a stew of edible goodies and turtles move
in to take advantage of the bonanza.
Migrating to ephemeral waterbodies when the rains come give the turtles
another advantage - they get one jump ahead of the fish. Fish are
the turtles' major competitor for food, but unlike turtles, they are
unable to invade the isolated temporary swamps. This is also the ideal
time to breed, when turtles are plump from gorging themselves on the
bounties of the swamp.
These mass migrations happen only once every few years and then, as
the ephemeral swamps dry up, the turtles turn tail for their lakes
in the dunes, to wait out the lean times until the food bonanza begins
again.
The waiting game
The charming Macquarie turtle (Emydura macquarii), like the long-neck,
is able to live in urban areas. Image: Carol Browne, University of
Sydney
Intimately linked with their migration is the turtle's ability to
go into a state which is similar to hibernation. Turtles - like all
other reptiles - are not able to internally control their body temperature
and this is where they pull out one of the finest tricks of the turtle
trade.
To beat the heat and also to survive the cold winter waters, turtles
begin to drop their body temperature, slow their pulse rate, and begin
using stored body fat instead of eating.
They may find a log and tuck themselves away under it, or bury themselves
several centimetres deep in some damp leaf litter for a short while.
Sometimes if the water is not too cold, turtles rest on the bottom
in large groups, not eating, and only occasionally coming up for air.
In captivity, long-necks in winter may not hibernate, but instead
just show little interest in food in winter.
With the autumn rains, turtles are busy migrating to more abundant
ephemeral ponds after waiting out the long drought in more permanent
watercourses. Now, as the weather begins to cool, they will slow down
their activity. When the water temperature drops below 11 degrees
C, this is their signal to remain on land and find a damp, sheltered
spot to wait out the cold winter days. In the southern areas, they
may hibernate under a log or bury a few centimetres under leaf litter
for several months, not eating at all. Others in warmer areas will
remain active, and may even mate up until May.
City life
With the coming of Europeans to Australia, turtles have faced one
of their toughest tests yet: urban living. Many turtles struggle on
in pockets all over big cities like Sydney, and can be found in the
most unlikely places, somehow surviving despite a host of environmental
pollutants that wiped out most other wildlife years ago.
Road runoff, heavy metal fallout from the air, illegal dumping and
sewage discharges are just some of the sources of pollutants which
could be affecting urban turtle populations, says Carol Browne from
the University of Sydney. Carol has found yet more incredible evidence
of just how hardy the turtle is. "I've caught them in some really
filthy places, where you can smell the oil, there's garbage on the
bottom of the creek, there are bubbles coming up with sulphur gas.
They're pretty tough."
Carol Browne finds another turtle living in a creek in densely populated
Sydney. Image: Carol Browne, University of Sydney.
Carol even found a population of turtles which had been living in
a raw sewage pit in a sewage treatment plant for several years. "There
were a few turtles which washed down a drain six years ago into this
pit, and since then, the population has exploded. The water is bright
green and bubbling, there's no oxygen in the water and you can see
methane coming off." Yet they survive.
This survival is testimony to the long-neck's mighty ability to resist
disease and infections, just like its distant relative, the crocodile.
Long-necks have been known to survive quite horrific injuries: Carol
has seen the whole shell of a turtle broken from the front to the
back and partly pulled away after it was run over by a car, yet the
turtle recovered. Another turtle was found with a perfect circle-shaped
hole in the middle of its shell, the edges quite healed over. The
theory: at some time in the past, it was stepped on by a cow.
Carol also measures heavy metals in turtle blood, as well as checking
the hatching success of eggs from turtles living in urban environments.
It's early days, but she is finding accumulating lead levels, which
is known to cause problems in bird eggs. There is also evidence that
feral animals are having an impact, with many turtle eggs being dug
up by foxes. Hampering the research is the lack of knowledge about
long-neck turtles. There is no baseline data for lead levels, and
no information on what sort of population levels were in Sydney in
the past.
What makes it doubly difficult is that turtles are incredibly long-lived
perhaps 70 years or more, so it could be decades before it becomes
obvious that they are no longer replacing themselves. So despite all
its turtle toughness, the hardy long-neck may soon become a rarity
in urban areas. Hopefully, though, it will continue to be found out
in the bush, wandering along quiet country roads. But if you do see
one out there, don't forget: if you suddenly get the urge to rescue
it, you could be in for a nasty surprise.
Turtle facts
Turtle or tortoise?
Although sometimes called a tortoise, the longneck and all other Australian
turtles are indeed true turtles. Turtles have paddles or webbed feet
designed for swimming, whereas tortoises - such as the giant Galapagos
tortoise - have stumpy, solid feet which are far more suited to walking
on land. The webbed feet of long-necks are also clawed to make it
easier to walk about.
Appearance
The top shell of long-necked turtles is brown, black or dark green,
the underside white or creamy yellow. As the animal ages, the sides
of the shell turn up, with older turtles resembling a bowler hat.
As the name suggests, they have a very long neck which when extended
adds about 65 per cent to the overall length of the body. The neck
serves as a powerful aid in hunting, for long necks are pure carnivores.
No-one is quite sure how long they live, although it's probably at
least 70 years. They can grow to over 250mm long and weigh over 1.5kg.
The neck is covered with small, pointed bumps of skin.
Breeding
Nesting occurs usually between late September and December and several
clutches of between 8-24 eggs may be laid. They hatch after 120-150
days.
