he Red-eared Slider is a subspecies of the
Pond Slider (Trachemys scripta) which is
found in northern Mexico and much of the
eastern USA. The common name is derived from
the distinctive red stripes on the side of the head,
coupled with the turtles’ habit of sliding quickly from
basking spots into water if disturbed. Red-eared
Sliders are native to the Mississippi drainage
system, from southeast Colorado to Virginia and
Florida, south to northern Mexico. They are
immediately recognisable due to the unique red
stripes on their heads, in addition to which the head,
legs and tail are covered with conspicuous creamy-
yellow lines. They prefer slow-moving or still water
and are often to be found basking in numbers on
exposed rocks or logs. Although omnivorous, they
consume large amounts of aquatic vegetation.
Females are usually larger than males, and
maximum carapace length is around 40cm, although
most adult specimens are significantly smaller;
sexual maturity may be attained with a carapace
length of just 10-15cm. The Red-eared Slider has
become the most popular turtle in the global pet
trade, and has been exported around the world. It
has subsequently established naturalised
populations in all continents except Antarctica and is
ranked among the world’s 100 most invasive
species, which is ironic considering it is struggling
somewhat in its natural range. The Teenage Mutant
Ninja Turtles were identified in a comic book as
being Red-eared Sliders, and predictably this only
served to enhance the species’ popularity as pets.
In Europe, Red-eared Sliders have already
demonstrated their ability to displace native species,
and importation has been banned by the European
Union. In Australia, fears are heightened by the fact
that they attain sexual maturity earlier than native
species of freshwater turtles, plus they have higher
fecundity and are generally larger in size. Retained
sperm may allow a female to produce fertile eggs a
year after mating. Although the possible impact of
Red-eared Sliders in Australian environments is at
present almost wholly speculative, they may also
transmit a blood parasite, in addition to damaging
local ecosystems through predation and destruction
of aquatic plants and the nests of waterbirds through
their habit of basking on these structures. Red-eared
Sliders are also known to carry Salmonella bacteria
(although so are many other reptiles), and there are
concerns that drinking water could be contaminated,
and that handling could also result in salmonellosis.But do we really need to be worried? Are there
already naturalised breeding populations of
Red-eared Sliders in Australia? And if so, where
have they come from? The last question is the
easiest to answer as, like the rest of the world (and
the Corn Snakes found around Sydney), Red-eared
Sliders encountered in the wild in Australia are
believed to have originated from (illegally-held) pets.
In fact, naturalised Red-eared Sliders have been
found in Western Australia, the Australian CapitalTerritory, Victoria, Queensland and New South
Wales, with a number of known incursions in each of
the last three mentioned states.In Victoria, there have been reports of sliders in
Blackburn Lake since 2005, and three specimens
were captured up to 2013, with a similar number
removed from Elsternwick Park Lake. Red-eared
Sliders were first
detected in Queensland
in 2004, and since then
a number of populations
have been found – all
but one in farm dams.
Isolated specimens
have been found as far
afield as Bundaberg. In
the Sydney region there
have been sightings in a variety of locations. A
number of animals, including a gravid female, were
caught on a golf course in Woy Woy in the 1980s.
The existence of a breeding population in the
Yeramba Lagoon was confirmed by the capture of
six females in 1997-8, together with evidence of
nesting and a further four males in 2008. Three
sliders were recorded basking together in Lime Kiln
Bay in September 2016, and in January of the same
year two sliders were seen in Anzac Creek. Three
sliders have been observed together in Hacking
River at Audley, and at least two have been
captured in the Macarthur area. Five sliders have
been taken from Centennial Parklands, and there
have been at least 11 records of the species at this
location since 2009. However, this is easily trumped
by an aggregation of 12 large sliders seen basking
on a log in Rockdale Bicentennial Park in 2013!As well as compiling an invaluable synthesis ofknown sightings and incursions, Matthew Mo
concludes his article with a discussion that also
contains an evaluation of possible control methods.
These are hampered by the fact that upon any
disturbance, Red-eared Sliders instinctively swim to
the bottom and bury themselves deep in the mud.
Luckily, the Queensland incursions were almost
entirely limited to small farm dams, and effective
control was achieved
by draining and
de-silting to find the
buried sliders. Eradica-
tion is more difficult in
watercourses and high
visitation sites, which
suggests that natural-
ised populations in
Sydney may be much
more difficult to control, although basking traps in
particular offer some hope. Of course, it is also
possible that many other incursions have hitherto
gone unnoticed, but because Red-eared Sliders
have a distinctive appearance that is quite different
to native species of freshwater turtles, it is hoped
that appeals for assistance from the public will bear
fruit.It is obvious that this species has the potential to
very quickly develop into a major headache for NSW
authorities in particular.Reference & Further Reading:Matthew Mo (2018) Red-eared Sliders Trachemys
scripta elegans in southern Sydney, including new
incursions. Australian Zoologist In-Press.
https://doi.org/10.7882/AZ.2018.022Top left: Red-eared Sliders are often found basking in numbers
on exposed rocks or logs. Image by Elliotte Rusty Harold.
Below: their distinctive appearance is quite different to any
species of native Australian turtle. Image by Baishev.41