Oblong turtle or South-western snake-necked turtle

A freshwater turtle (sometimes called tortoise) that is common in southwestern Australian coastal plain wetlands and in other higher rainfall parts of the southwest of Western Australia. It can withstand short periods in salty water, as shown when turtles recover after being washed into the ocean from the Herdsman Main Drain discharge at Floreat Beach. 

Friends of Perry Lakes has commenced recording nesting and turtle sightings, both live and dead.   Email our Wildlife Officer to report your sighting and send an image (ensure your phone is on 'location' to record the exact time and location)  You can also contribute to an Australia-wide citizen science project through TurtleSAT.

Fast Facts

• Mostly seen in southern part of East Lake due to most permanent water supply
• Cannot survive long on dry land
• Not a threatened species, but losing habitat to dry and salty conditions
• Females seek sandy and open soil nesting sites away from wetlands
• Lifespan 30-40 years or more
• Numbers thought to be in decline possibly due to habitat/nesting site loss, predation on females when nesting.  Friends of Perry Lakes aim to plant low lying shrubbery for protection 
• Low survival rate of juveniles
• Males outnumber females about 2 to 1 in East Lake due to predation of females and road deaths while nesting
• Side-necked turtle therefore unable to completely retract neck/head under shell and legs are always partly exposed

Habitat

• Require open water for feeding, breeding and protection from predators
• Migrate between lakes, evidence by carcasses sighted between East/West Lakes and Camel Lake in Bold Park, possibly through now infilled South Lake
• Bury themselves in bottom of wetlands when lakes/swamps dry out or water temperature increase

Food

• Apex predator in wetlands; eat mainly macro-invertebrates such as dragon flies, insects, tadpoles
• Adult diet changes seasonally
• Will consume frogs, fish, ducklings
• Hatchlings eat midge or mosquito larvae and aquatic plants

Reproduction

• Nesting is initiated by rain-bearing low pressure systems, fall in barometric pressure and air temperatures above 17 degrees Celcius
• Two distinct nesting seasons. 8 - 14 eggs in up to three batches between September and November. 4 eggs in up to three batches between December and January
• Laying takes about 90 minutes; predation risk for females. Hind legs dig nesting sites several centimetres below surface
• Nests are made in sandy, open soils, within about 500m of water
• Same nesting site each year may be used
• 160 – 250 days incubation, temperature and rainfall are likely triggers for emergence.
• Hatchlings usually emerge in May/June (not all on same day) or as late as September, although higher temperatures may be shifting hatching as early as March.

Threats

• Ravens (can peck out their eyes), foxes, dogs, cats
• Australian white ibis which breeds in Herdsman Lake and now feeds in Perry Lakes
• Predation during nesting
• Fertilisers in wetland catchments may be harmful
• Road deaths during search for nesting sites

Friends of Perry Lakes management “wish list” 

• Deliver safe corridors for females during nesting site searches
• Identify ideal plants which offer protection, especially from ravens. A study of Bibra Lake turtles demonstrated that nesting occurred mainly in remnant natural habitat with greater canopy cover. Turtles generally avoided nesting in modified environments such as lawns and impervious surfaces.

Notes of interest

• Friends of Lake Claremont have developed a network of sandy areas and protective vegetation suited for egg laying. If a nest is found, they use a metal mesh to prevent eggs from being dug up by predators. This can cause problems for people mowing if the nest is in a grassy area. There needs to be communication with workers about the location of nests so that they are not damaged by mowing or dumping woodchips over nests. 
• Turtles in Perry Lakes Reserve have been seen to lay eggs south of East lake, making a raised walkway here desirable. They need a sandy area to lay eggs so dense turf is not suitable. It is not known if they use the islands in the lakes, but they may be too overgrown to be used. 
• Protection of turtles crossing Perry Lakes Drive from vehicles also needs attention, including the possible use of a tunnel under the road and how its use might be optimised. A study undertaken at Murdoch University showed that increasing light in the tunnel through treatments that simulated an open grate system significantly increased the likelihood of a successful and faster passage of turtles, while tunnel length had no effect. Tunnels may therefore be an option to allow turtles to cross Perry Lakes Drive.
• It is unclear if turtles suffer diseases if crowded, whether they are affected by algal blooms, and whether introduced fish (carp, pearl cichlids) offer an opportunity or a threat. We need information from Herdsman Lake where all exist together. 

Photo of Oblong Turtle courtesy Alexandra Kivilaakso Keow, from the Town of Cambridge. 

References:

Department of Water and Environmental Protection (2024). South-western snake-necked turtle - Chelodina colliei. https://rivers.dwer.wa.gov.au/species/chelodina-colliei/ 

Santoro, A., Chambers, J. M., Robson, B. J., and Beatty, S. J. (2020). Land use surrounding wetlands influences urban populations of a freshwater turtle. Aquatic Conservation: Marine and Freshwater Ecosystems. doi: 10.1002/aqc.3324.

Santoro, A., Newsome, R., Regan, Z., Chambers, J.M. & Beatty, S.J. (2023). Optimizing road underpass design to maximize use by a freshwater turtle (Chelodina oblonga). Aquatic Conservation: Marine and Freshwater Ecosystems, 1–8. https://doi.org/10.1002/aqc.3982 

Santoro, A., Chambers, J. M., Ebner, B. C., Sturm, A. L., and Beatty, S. J. (2024). Long‐term habitat degradation affects nest site selection behaviour by a freshwater turtle (Chelodina oblonga) in Western Australia. Aquatic Conservation: Marine and Freshwater Ecosystems 34. doi: 10.1002/aqc.4085.