This is the story of how Antonia found herself in the middle of nowhere wrestling crocs on a study with PhD student Ruchira Somaweera. An experience that left her with more than an award winning thong tan on arrival back home to a little town called Sydney

1. SAVING OUR NOT
SO FURRY
FRIENDS
FRESHWATER CROCODILES AT
LAKE ARGYLE

2. Toto, I don’t think we’re in
Kansas anymore…
• Hi there, my name is Antonia
Quinlivan.
• I’m a 3rd year Animal &
Veterinary Science student at
the University of Sydney.
• This is my story of how I found
myself in the middle of nowhere
wrestling crocs on a study with
PhD student Ruchira Somaweera.
• An experience that left me with
more than an award winning thong
tan on arrival back home to a
little town called Sydney.

3. The aim of our research was to broaden our knowledge of
one of the most phenomenal “living dinosaurs” we know
today.

4. You can volunteer too
• The long term
objective of the
research program is
to gain a better
understanding of the
ecology and
physiology of the
crocodile so that a
conservation strategy
can be put in place.
• Volunteers in the
study capture
crocodiles of all size
classes.

5. You can volunteer too
• They assist with
measuring, weighing,
sexing, stomach
pumping and tagging of
crocodiles.
• They also assist in the
attachment of radio- radio- telemetry
telemetry devices that device
will be used to monitor
movements and to
determine home range
sizes of the animals

6. You can volunteer too
•During the breeding
season, volunteers
participate in nesting
surveys carried out by
boat and on foot.
•They help collect eggs
and monitor egg
incubation for the
temperature-dependent
sex determination study.

7. You can volunteer too
• They raise hatchlings in
order to determine
growth rates.
By providing scientific
expertise and detailed
biological information
we can effectively
manage threats to
crocodile populations

8. Economic and environmental
benefits of this study
• Crocs are an iconic tropical animal in
Australia.
• Lake Argyle has the highest
population of freshwater crocs and
plays a big role in the tourism
industry- direct benefit.
• Freshwater crocs are the top
predators in the ecosystem,
therefore the study holds great
ecological value.
• Conservation of this species in this
habitat has benefits for conservation,
tourism and animal health.

9. Where is Lake Argyle?
• With an area of 880km2 at normal water level, Lake
Argyle is the largest man made lake in Australia.
• It contains the highest density of Freshwater
Crocodiles (Crocodylus johnstoni) in Australia.
• In 1989, a boat spotlight survey estimated croc
populations of 25,000 (G Webb Pty Ltd, 1989).
Magnificent part of Aus-
BREATHTAKING!
•http://www.lakeargyle.com.au/images/lake-argyle-aus-map02.gif

10. The Problem
Current threats to
our crocs in Lake
Argyle include:
• entanglement in
fishing nets
• Predators such
as varanid
lizards, pigs and
dingoes who
remove and eat
crocodile eggs
from nests.

11. The Problem cont…
My goodness they
AND CANE TOADS!!! are everywhere and
mum warned me not
to eat them!!!!
Did I listen?
•It is predicted they will
soon colonise the shoreline
of the lake.
• AND CANE TOADS KILL
CROCS THAT INGEST
THEM!!! (Letnic et al. 2008).

12. The research aims and
objectives
Ruchira’s hopes his study
will fill information gaps
on crocodiles
He is looking at their:
1. Demography
• Growth
• Recruitment
• Age
• Structure
2. Biology
• Diet
• Movements
• Habitat.

13. What we were interested
in
Ruchira’s study will
look at:
•the diversity of
their habitats
•their feeding
and nesting
behaviour
•How they care
for their young.

14. What did I do to help?
• I was part of a team that helped
Ruchira collect information on the
population status, distribution and
abundance of these animals in their
aquatic system.
• We collected last year’s hatchlings
and marked them so could monitor
their growth, dispersal and observe
their behaviours.
• We went on foot surveys, daytime
boat surveys, night-time spotlight
surveys.
• We helped capture, measure, weigh,
stomach flush and tag crocodiles of
various size classes.

15. What did I do to help cont..?
• We set up baited remote
cameras to study abundance
and diversity of the land
predators on the shoreline.
• We looked for and found
crocodile nesting sites and
examined crocodiles at close
quarters in search of
ectoparasites and learnt
about data capture and
analysis.

16. What is an ectoparasite you
ask?
• Insect ectoparasites are those insects that live on the
outside of other animals (ecto = outside).
• Most of these insects survive off the blood of their hosts,
although some also eat skin, hair and other secretions.
• To qualify as a true ectoparasite you must have an intimate
relationship with your host. For example, mosquitoes are not
ectoparasites; they do not live on humans, but only visit for a
blood meal.
• Insect ectoparasites are often highly adapted to their
specialised host environments.
• Typical adaptations include loss of functional wings,
flattening of the body, strong legs and claws for clinging
onto the host, and biting or sucking mouthparts for taking
blood meals."

17. So can you think of some?
• Leeches?
• Lice?
• Mmh not nice but sometimes it works for
both species. For example the tiny
blackbird plover acts as a toothpick for
the fierce crocodile and helps by removing
tiny morsels of food that is stuck between
the crocodile's teeth. Surely there must
be a less risky way to get food than this?
• Read more here http://australianmuseum.net.au/Insects

18. Why we doing this research?
•Understanding these key
elements will help predict
how cane toads, predators
and fishing will affect
Lake Argyle crocodile
populations.
•This information will help
to develop effective
management and
conservation techniques
for freshwater crocs.

19. RISKY WORK!!!
• We found out CROCS
BITE!!!
• We suffered from
dehydration and
heatstroke and insect
bites.
• We got caught in
storms on the river.

20. How did we minimise the
risk? OMG does my
insurance cover
• We were supplied this ?
with safety gear on
the boat (satellite
phone, EPIRB, flares,
life jackets)
• The Volunteer
Workers Policy of Uni
of Sydney provides
liability cover and
personal accident.

21. What did we find out?
• Crocs have no resistance
to bufotoxins in cane
toads.
• FYI. Bufotoxins are a
family of toxic
substances found in the
parotoid glands, skin and
venom of many toads
(genus Bufo); other
amphibians; and some
plants and mushrooms.
http://en.wikipedia.org/wiki/Bufotoxin

22. What did we find out?
• There was a 77% reduction in the
crocs population after cane toads
invaded the Victoria River in
Northern Territory
• It will take differing management
techniques to remedy mortality as
a result of serious injury of croc
captures in nets and resolve
problematic food chain pathways as
a result of croc-fishery
interactions.

23. Future direction
• The intensity of toad impact relates to cane toad densities,
availability of alternative prey, the prey-preference of crocodiles,
genetic resistance and the innate ability to learn in crocodiles.
• These factors are being investigated through field and laboratory
studies and may give insight to the level of impact and how soon
populations may recover after the invasion.

24. Potential of Conditioned
Taste Aversion Learning!
• Previous studies on northern quolls
(Webb et al. 2008) were successful in
training quolls to avoid cane toads Spotted
before they invade.
Quoll
• The method involves deploying baits
containing a non-detectable nausea-
inducing chemical ahead of invasion.
• Predators consume bait, become ill,
subsequently avoid consuming live
toads on arrival.
• A future project will examine whether
crocs will consume non-toxic chicken
baits.

25. How this study was made
possible?
• Ruchira is based in the
“Shine Lab” at the University
of Sydney.
• The Shine Lab is named
after Professor Rick Shine
who conducts research on
the interface between
evolution and ecology,
particularly in reptiles
(snakes and lizards).
• In recent years he has
shifted his focus to major
issues in conservation -
especially the biology, impact
and control of invasive
species such as the cane
toad.

26. Who funds the study?
The project is funded under 3 grants:
1. Australian Research Council grant to
Rick Shine.
2. Crocodile Specialist Group Research
Grant.
3. University of Sydney Post Graduate
Research Grant.
Some funding support was provided
through a grant obtained by Jonathan
Webb from a Caring for our Country Grant
Government groups like Dept of
Environment and Conservation (DEC) and
Dept of Fisheries also work with Ruchira
to find appropriate fishing grounds for
locals and tourists.

27. Challenges of the study
• Working in such a remote area creates
some logistic problems such as:
– Safety issues of working alone.
– Getting assistance from community
groups and research organisations to
support the study
– The need for ongoing support from
volunteers to allow Ruchira to
complete his study on time.

28. Conclusion
• We now know that our
freshwater crocodiles face
a potentially life
threatening future from
the predicted cane toad
invasion of Lake Argyle.
• It is studies like Ruchira’s
that find solutions to
conserve Australia’s
wildlife.
• Without volunteers, these
studies would not be
possible!

29. Personal Reflection
• My time at Lake Argyle in the
summer of 2009 was the
single most life changing and
eye opening experience I have
had up to date.
• I was fortunate enough to see
a part of our beautiful country
that I wouldn’t have
experienced without being
exposed to such studies
through Uni.
• I made invaluable connections
and lifelong friends.
• Everyday was a challenge- and
it got better each day. I’d be
back in the 40+ degree heat
jumping on crocs in a
heartbeat!

30. What you can do
SIGN UP AND VOLUNTEER FOR THE STUDY!!
• Drop Ruchira an email: ruchira.somaweera@gmail.com
• or check out his website at
www.bio.usyd.edu.au/sites/Shinelab/students/ruchira/ruchira.html

31. What you can do
• Get on board with a toad collection campaign and help out with the
annual muster.
Join:
– Stop the Toad Foundation.
– Kimberley Toad Busters.

32. References
• G. Webb Pty Ltd 1989. The results of
crocodile surveys in Lake Kununurra and Lake
Argyle (Western Australia), February-March
1989. Report to CALM, 1989.
• Letnic, M., J.K. Webb, & R. Shine. 2008.
Invasive cane toads (Bufo marinus) cause
mass mortality of freshwater crocodiles
(Crocodylus johnstoni) in tropical Australia.
Biological Conservation 141:1773-1782.
• Webb, J.K., G.P. Brown, T. Child, M.J.
Greenles, B.L. Phillips, & R.Shine. 2008. A
native dasyurid predator (common planigale,
Planigale maculata) rapidly learns to avoid
toxic cane toads. Austral Ecology 33:821-829.
THANKS!!!

33. WOULD LIKE TO THANK THE SPONSORS OF THE
2010 CREAM OF THE CROP COMPETITION
PLATINUM GOLD SILVER
BRONZE