Reptiles

Shell Shocked

Earlier this year I mentioned how we haven’t seen as many turtles as we did last year.

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That changed the last couple of weeks and we have seen quite a few.

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The turtles I have seen lately do not appear to have any colour, which the Painted Turtles have.

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I think these are Northern Map Turtles.  However, I don’t see the pattern of yellow lines that look like a contour map, but they do fade as the turtle matures. Several times I have seen three basking together, (one had jumped into the lake by the time I took the picture!)

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I was a little concerned a boat propeller hit this turtle. However, I have since discovered that turtles do something called scute-shedding. They do this when they grow and to get rid of shell rot or parasitic infections. Scutes are the outside layers of the shell, similar to fingernails. They protect the bones and cartilage of the shell underneath. The shell of a turtle grows with the turtle and is actually the turtle’s rib cage and spine. It is attached to the internal bones of the turtle’s body.

Fractured shells due to boats are a big concern for Northern Map Turtles. Northern Map Turtles have a status of Special Concern, because their numbers have declined and collisions with motor boats is named as one of the reasons for the decline. Studies have shown that females seem more vulnerable than males by as much as nine times. When mortality is greater than 10% the risk of population extinction becomes quite rapid, which is a huge concern. The adult female Northern Map Turtle is twice the size of an adult male and they bask more at the surface of the water than males, which puts them more at risk of being hit by boats. Their diet is different too. Females mostly eat molluscs, clams and snails, along with some crayfish and some fish. Males and young Northern Map Turtles mainly eat insects and crayfish. As it takes more than 10 years for a female to reach maturity, the decline in female numbers is certainly a “Special Concern”.

I have mentioned before that road traffic is another area that is impacting turtle mortality. Another area of concern for these turtles is the control of waterways, which in our case is the Rideau Canal lock system, which can submerge nesting sites. The water level has been so low this year. If that changes next year it could alter the habitat enough and flood nesting grounds. The eggs hatch in the fall and in some cases the hatchlings overwinter in the nest. Last year we found a nest quite near our dock and it was on much higher ground, so hopefully they will return to a similar spot and stay safe!

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