The Snapping Turtle is Ontario’s largest turtle species. The average adult male carapace (top shell) length is 25-40 cm and the average female carapace length is 23-36 cm. The Snapping Turtle’s carapace can be light brown, olive, or black with serrated edges around the top shell. Their plastron (bottom shell) is much smaller in size compared to other turtles, and it is cross shaped. The plastron can be yellow, tan or grey. Snapping Turtle shells are often covered in mud and algae, so colour can be hard to identify. Key identifying features are size- adults are much larger than other species, as well as their beak-like mouth with the top part hanging over the lower. Their head and legs are also very large and they are unable to tuck their appendages into their small shells. Their tail is also very long and has triangular spikes along the top. Males and females are nearly impossible to distinguish unless you see one nesting. Hatchlings and juveniles look just like the miniature version of adult Snappers.
Snapping Turtles are primarily omnivorous, but they will also scavenge on recently dead carcasses. In sampled adults, plant matter is generally more abundant than animal matter in stomach contents, so plants likely play a larger part of their diet. They will eat plant matter like algae, duckweed, pondweed, cattails, sedges, and water lilies. Snapping Turtles also feed on molluscs, crustaceans, insects, small fish, frogs, other juvenile turtles and birds. When hunting for animal prey, adults are more likely to lie on the bottom and ambush their prey, whereas younger individuals will more actively forage.
Biology and Behaviour:
Snapping Turtles regulate their body temperature most often by basking in water, floating at surface, or staying at very shallow depth. They will also leave the water to bask on logs, rocks, or the shoreline especially on warm and clear days. Snapping Turtles are typically active during the day, and are especially seen on warm rainy days during nesting season when females search roadsides for a nesting spot. When confronted by a threat on land. adults will turn defensive and attempt to strike the threat by “snapping”, where they extend their long neck quickly and snap or bite. This aggressive behavour is thought to occur since Snapping Turtles have a small shell and cannot hide like other turtle species can. In water, Snapping Turtles are much less aggressive and they will usually flee or conceal themselves in sediment when faced with a threat.
Snapping Turtles will emerge from hibernation underwater in early spring and make their way to their breeding habitats. Mating takes place in early spring, and nesting season usually begins in late May until early July. Female Snapping Turtles will travel up to 500 m away from water to find a suitable nesting site. They especially prefer to nest on warm rainy days and along roadsides, making nesting season an extremely dangerous time for adult females. Snapping Turtles will take hours to dig the perfect nest and lay their eggs in a perfectly excavated cavern, buried fairly deep into the ground. They are also known to dig many “test nests” either to confuse predators or to find the perfect spot. A single Snapping Turtle nest can have 12-50 eggs, but generally average around 36 eggs that are a bit smaller than a ping pong ball. Like all turtles, the sex of the hatchlings depend on the temperature that they are incubated in. Eggs usually hatch 65 to 95 days after they are laid, which is between late August and early October. After emerging from the nest, hatchlings usually make their way towards water and bury themselves under the mud in shallow depths.
Snapping Turtles hibernate under the water, preferring water that is shallow enough for them to reach the surface to breathe, but deep enough that water will not freeze at bottom. They also prefer a thick layer of mud to bury themselves into, and submerged cover like floating vegetation or logs. During hibernation, they can tolerate low body temperatures as low as 1̊C, and they can tolerate conditions with low dissolved oxygen in the water. Like all turtle species, they will generally return to the same hibernation site each year if it was successful. Sometimes Snapping Turtles will lay a second clutch of eggs in the late summer, and these hatchlings will overwinter in their nest. If they are able to survive the conditions, they will emerge in the spring.
Adult Snapping Turtles do not generally have any predators, their main threat is actually humans and road mortality. However, the Northern River Otter has been known to prey on hibernating adults, and small adults or juveniles are sometimes killed by Mink. Snapping turtles are most vulnerable to predators at egg and hatchling stages, when nests are predated. The most common nest predators of Snapping Turtles are Raccoons and Red Foxes, but Skunks, Coyotes and Opossums are also occasional predators.
- Adult Snapping Turtles are very distinct looking because of their long tail, large size, and general appearance, so they aren’t’ usually mistaken for other Ontario turtle species
- Hatchlings and juveniles are sometimes mistaken for other turtle species, but they can be distinguished by their beaked mouth, serrated top shell, small plastron (bottom shell), and the rows of triangular plates on their long tails
Conservation and recovery strategies:
Governments and organizations should use conservation and recovery strategies that identify hotspots of high road mortality and develop mitigation approaches. These can include ecopassages/corridors/underpasses, putting up signage to “watch for turtles”, and reducing speed limits. Construction of new roads in or near wetland habitats should be discouraged. Restoring and preserving suitable habitat through land acquisition and stewardship should occur, as well as educating and informing the public on Snapping Turtles to teach them that they are not dangerous and they cannot harm you.
There are organizations like The Land Between that are striving to eliminate Snapping Turtle misconceptions and show people that these amazing creatures deserve to live. There are volunteer programs that help turtles cross the road during active seasons, and turtle hospitals like the Ontario Turtle Conservation Centre that will rehabilitate injured turtles and release them back into their territory. The Land Between also has the ability to excavate turtle eggs along dangerous roads where they are safely incubated and released back on site when they hatch. Look up your local turtle organization and see what you can do to help!
- Hatchlings and juveniles are not able to effectively snap or bite yet, so instead they secrete a foul-smelling amber liquid to try and deter predators. Adults can do this as well, but their main line of defense is to snap if threatened to protect themselves
- Snapping Turtles cannot bite off your fingers or toes! Their bite may hurt but they do not have the jaw strength to bite through a carrot
- Snapping turtles snap because they can not retreat into their shell– they are too large to be able to do this, whereas most other turtle species are able to protect themselves this way. They will snap on land if they are feeling threatened, but in water they will retreat or bury themselves at the bottom
Kimmons and Moll. 2010. Seed Dispersal by Red-Eared Sliders (Trachemys scripta elegans) and Common Snapping Turtles (Chelydra serpentina)
Obbard and Brooks 1979. Factors affecting basking in a northern population of the common snapping turtle, Chelydra serpentina.
Obbard and Brooks 1981. Fate of overwintered clutches of the common snapping turtle (Chelydra serpentina) in Algonquin Park, Ontario. Can. Field Nat. 95: 350 352.
Moldowan et al. 2015. Diet and feeding behaviour of Snapping Turtles (Chelydra serpentina) and Midland Painted Turtles (Chrysemys picta marginata) in Algonquin Provincial Park, Ontario
Environment and Climate Change Canada. 2016. Management Plan for the Snapping Turtle (Chelydra serpentina) in Canada [Proposed]. Species at Risk Act Management Plan Series. Ottawa, Environment and Climate Change Canada, Ottawa, iv + 39 p https://www.registrelep-sararegistry.gc.ca/virtual_sara/files/plans/mp_snapping%20turtle_e_proposed.pdf
COSEWIC. 2008. Snapping turtle (Chelydra serpentina): COSEWIC assessment and status report 2008. Committee on the Status of Endangered Wildlife in Canada. Ottawa. Retrieved from https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/snapping-turtle-2008.html
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