Chelodina longicollis
Common Snake-necked Turtle

Chelodina longicollis is endemic to Australia, and its geographic range extends from the Wilton River in eastern Queensland to the Murray River, along the south western border of New South Wales. Its geographic range includes the entire Murray-Darling Basin. ("Australo-American sideneck turtles", 2003)

Common snake-necked turtles are semi-aquatic. Although they prefer the slow moving waters of swamps or wetlands, they can also be found in streams and rivers. In aquatic environments, they are primarily bottom dwelling, but occasionally leave the water to bask in the sun. If conditions are dry, they seek out new habitat. Some individuals seek extended refuge and may estivate until flood waters return. Estivation usually occurs under trees in forested habitats where they can burrow into fallen foliage on the forest floor near shrubs and logs. Common snake-necked turtles are usually the only turtle species in their immediate environment. ("Australo-American sideneck turtles", 2003; Kennett, et al., 2009; Roe and Georges, 2008a)

Common snake-necked turtles are medium-sized turtles, with an average length of 25 cm. They have a black to light brown oval carapace that contains a shallow central groove. The plastron is cream colored with dark seams. Their necks are long and narrow, with a brown to gray dorsal surface and a yellow ventral surface. On average, the neck is approximately 60% of the plastron length and is covered with short tubercles. The head is small and pointed and the limbs are dark grey to brown. Sexual dimorphism in this species is subtle. When compared to males, females are larger, have deeper shells and have a shorter, fatter tail that is hidden. Males have longer, thicker tails than females and a concave plastron. These distinctions are subtle which makes gender determination difficult. Juveniles tend to be black to dark gray with an orange stripe down either side of the neck and jaw. They also have orange spots on the plastron. ("Australo-American sideneck turtles", 2003; Ernst and Barbour, 1989; Kennett, et al., 2009)

There is little information about the development of Chelodina longicollis. Adult females lay their eggs near water's edge, and embryo estivation occurs as the eggs develop. Sex determination is not based on incubation temperatures, which is unlike that of most chelonian turtles. ("Australo-American sideneck turtles", 2003; Kennett and Georges, 1990)

Chelodina longicollis is polygynandrous, and during breeding season, males become more active and travel longer distances, which increases their their potential number of matings. Females increase movement during nesting periods to find optimal nesting sites. Males engage in head bobbing and cloacal touching during the mating sequence and attempt to align barbels with those of females. In preparation for copulation, which occurs in the water, males mount females from the rear and align their plastron over the females carapace. Occasionally, females struggle free of their mate but males rarely retreat. Copulation occurs while the male and female plastrons are directly adjacent from one another. Chelodina longicollis lacks many of the complex mating behaviors present in other species and freely mates with Chelodina canni; however these two species are rarely sympatric and thus, hybridization rarely occurs. (Kennett, et al., 2009; Murphy and Lamoreaux, 1978; Roe and Georges, 2008b)

Common snake-necked turtles breed once annually, from September to October. Nesting occurs during late spring and early summer, from October to December. Females lay 8 to 24 hard-shelled, ellipsoid eggs in nests close to water. Eggs are approximately 20 mm wide and 30 mm long and weigh between 6 and 7 g. Typically, females lay three clutches per year are all eggs are laid. Embryo estivation occurs during development, with incubation lasting between 120 to 150 days. Young emerge during autumn, from January to late April. Common snake-necked turtles are slow to mature, and most males reach sexual maturity between 7 and 8 years of age. Females reach sexual maturity between 10 and 12 years of age. Male-female birth ratio is approximately 1 to 1. Reproductive success is greater for swamp populations than for residents of permanent lakes, as their is significantly less competition for resources in wetland habitats ("Australo-American sideneck turtles", 2003; Ernst and Barbour, 1989; Kennett and Georges, 1990; Kennett, et al., 2009; Roe and Georges, 2008b)

Prior to laying their eggs, Chelodina longicollis females search for optimal nesting sites and may travel more than 500 m from water to find nesting sites on elevated landscape structures (e.g., crests or ridges). Nesting can occur in a variety of substrates, from soft sand to hard clay, and has even been documented on gravel roads. Prior to excavating the nest, which is simply a large hole for which females to lay their eggs in, females eject large volumes of cloacal fluid on the nest site, which helps soften the ground. Females excavate the nest with their hind claws and may return to the nearest source of water multiple times to take on more water to soften the earth for excavation. Once eggs have been laid, excavated substrate is placed back into the hole with her rear claws. The female then compacts the loose soil by raising her body and suddenly collapsing on top of the nest. There is no information available on paternal care in this species. (Kennett, et al., 2009; Roe and Georges, 2008b)

The average life span of Chelodina longicollis ranges from 31 to 37 years. The lifespan of wild and captive individuals appears to be approximately equal; however, very few have been held in captivity. During dry periods, C. longicollis moves to more permanent bodies of water (e.g. lakes), where resource competition is high. As a result, many individuals die and thus, longevity tends to be higher in wetland habitats than in permanent lake. Females are able to withstand these pressures better than males because of their larger size. (Kennett, et al., 2009)

Common snake-necked turtles frequently change habitats. During breeding seasons, males and females are known to increase movements and environmental conditions (e.g., rainfall and moisture levels) can have an impact on local densities of common snake-necked turtles. They are known to move great distances to find a suitable habitat. Although many individuals can live in the same wetland, they are generally thought of as solitary and move independently of one another. Common snake-necked turtles have good water storage capabilities, which allows them to lie dormant or estivate for extended periods of time. ("Australo-American sideneck turtles", 2003; Roe and Georges, 2008b; Roe and Georges, 2008a)

Chelodina longicollis has a large home range, which increases as distance between wetlands increases. Evidence suggests that movement depends on rainfall amounts. As annual rainfall decreases, movement tends to increase, and some individuals have been recorded to move up to 5.2 km. Distances between wetlands or permanent waters vary, and many individuals associate with more than one wetland over the course of several years. High rates of movement were recorded when wetland distances were no more than 1.2 km. On average, adult males move the greatest distance, while juveniles move the least. (Roe, et al., 2009; Roe and Georges, 2008b; Roe, et al., 2009)

Chelodina longicollis is primarily solitary; however, communication between conspecifics usually occurs via touching or the release of pheromones. Individuals emit a pungent musk to deter predators. During mating, males perform head bobbing and fast swimming in an attempt to gain the attention of females. Chelodina longicollis perceives the immediate environment through visual, haptic, and olfactory stimulation. (Murphy and Lamoreaux, 1978; Roe, et al., 2009)

Chelodina longicollis is carnivorous and is an ambush predator. Primary prey includes aquatic invertebrates, fish, tadpoles, crustaceans, plankton and carrion. Occasionally, they prey upon terrestrial insects. Intraspecific competition has been known force movements between habitats. Prey are caught by the use of a strike and gape action, and are sucked into the turtle’s mouth by a vacuum that is created by the sudden lowering of the hyoid bone. When food resources are limited, C. longicollis preys upon a large variety of small organisms. ("Australo-American sideneck turtles", 2003; Kennett, et al., 2009)

Predators of common snake-necked turtles include red foxes, water rats, goannas, Australian ravens, white-breasted sea eagles and dingos. When fox predation is high, populations tend to be dominated by adults, as foxes primarily prey upon juveniles and eggs. To deter predators, common snake-necked turtles emit a foul-smelling musk, or yellow fluid from their musk glands. When threatened, individuals tuck their head into their shell and lean into the threatening organism with their shell. The also perform defensive snapping when threatened. (Kennett, et al., 2009; Thompson, 1983)

Chelodina longicollis feeds on aquatic invertebrates, fish, tadpoles, crustaceans, and plankton. It is also a major prey item for Vulpes vulpes, which is not native to Australia. There is no information available on parasites of this species. (Kennett, et al., 2009)

The common snake-necked turtle is commonly hunted by indigenous Australians for their meat. They are also studied as biological indicators of wetland habitat quality. ("Australo-American sideneck turtles", 2003; Roe, et al., 2009)

There are no known adverse effects of Chelodina longicollis on humans.

Chelodina longicollis is not listed on the IUCN Red List of Threatened Species and is thought to be a species of least concern. Important potential threats include habitat change, climate change, and nest predation by invasive red foxes. This species is currently protected under state and federal legislation in Australia; however, specific conservation measures are not high priority. Currently, they are widespread and abundant throughout their geographic range. (Kennett, et al., 2009)