The wood turtle and the effects of human interactions

The wood turtle (Glyptemys insculpta or Clemmys insculpta):

As made obvious in the picture above, the wood turtle has a unique colouration that makes this species easy to recognize.  Although I have chosen an individual turtle that is particularly bright, the colour on the legs and neck can often vary over a wide spectrum.  These turtles can be brown, yellow, orange (as pictured), or even a brick red.  The carapace measures between 13 to 23 cm and is characterized by growth rings which can be used to determine the turtle’s age (25).  If you watch the video below, there is some great information on this species.  In addition, the age rings are depicted well.

Credit YouTube user: WisCBMnetwork

The wood turtle can be found over a wide range of habitats, as they like to spend time in both land and water.  Southern Ontario is home to the largest population of this species, with 412 individuals at last count (25).  Its distribution in Ontario can be found below:

Adult turtles are omnivorous, meaning that they eat both plants and animals.  Interestingly enough, young turtles are believed to be more carnivorous than adults.  Wood turtles like to munch on a number of things, including (but not limited to) berries, flowers, mushrooms, bugs and worms.  When these turtles are in more of a carnivorous mood, they will eat other turtle eggs and even baby mice and birds (25).  On average, Ontario’s wood turtles mature at an age of 17.  Northern populations tend to mature later than more southern populations.  After a female has matured, she will lay one batch of eggs annually, and her nest location preference will usually be on sandy river embankments (25).

The wood turtle was last assessed as “Threatened” by COSEWIC in November of 2007, and as a species of “Special Concern” by SARA.  As you may have noticed, this is the first time this week that COSEWIC and SARA designations don’t match.  A species of “Special Concern” is of a lower conservation priority than that which is considered as “Threatened”.  A more detailed look at the relationship between COSEWIC and SARA designations can be found here.  In Ontario, the wood turtle has been protected from being collected for the pet trade since 1984 (25).  Unfortunately, it faces some other problems.  Wood turtles are highly susceptible to road mortality, an effect of habitat fragmentation that I discussed on Monday.  This is still not the only means through which the wood turtle has come upon its “threatened” status.

Human interactions:

I think I am really just using human interactions as a euphemism for the negative effects of human interference.  Many species have shown decline in response to anthropogenic activities in nearby regions (3)(5)(7).  For example, the stinkpot (which I will discuss on Friday) has shown an unaccountable negative response to human presence.  Although this area has not been researched clearly, an anthropogenic connection has been established as a possible cause for this specie’s decline (7).  Wood turtles show a similar unaccountable positive correlation between number of injuries (limb loss, tail loss, shell fractures) and anthropogenic activity (26).

The spiny softshell turtle show a decline in livelihood in the direct presence of humans, this species is often the victim of recreational boating accidents (3)(27).  This is sadly not where the trouble ends.  In addition to motor boat collisions, these turtles are vulnerable to fisheries, since nets can accidentally trap them as bycatch (i.e. collateral damage) (3).  The spiny softshell is not alone in this predicament, as other Ontario turtles like the common snapping turtle and map turtle are also often found as fishery bycatch (28).  Although fisheries bring in necessary resources and may provide wealth for the surrounding area, it will be important in the future to consider a more sustainable approach with turtle trap doors or something along those lines.

In addition to these problems of direct contact, urbanized areas (and generally any areas with development) bring with them new sets of indirect problems.  Proximal anthropogenic activity leads to increased turtle predation (eggs especially) by urban scavengers/predators like crows, foxes, skunks, raccoons, cats and dogs (2)(25)(29)(30).  In the Blanding’s turtle, such predation has been pinpointed as the most significant cause of nest failure (18). Once again, my classmate (the same one as before) provided me with some stories from his field experience.  He stated that when people find turtle nests, they tend to return frequently just to look at them.  This leaves a trampled trail for other animals to follow.  He mentioned briefly that raccoons may have even learned to use this as a meal ticket.  Another threat to turtle nests is the effect of changing water levels caused by sewage or other forms of water management.  It’s wonderful that people are spending time outdoors and finding an appreciation for nature, this is very important for conservation efforts.  Conversely, this must be done so in a way that will reduce impact to minimal levels.  The flooding of turtle nests is a major contributing factor to decline in reproductive output of species like the spiny softshell, the Blanding’s, and the stinkpot (2)(31)(32).

It may not be a surprise that chemical contaminants are harmful to species as well. Despite the fact that the common snapping turtle is not one of my focal species, it is still one of Ontario’s turtles, and studies on their nesting behaviour exhibit this problem clearly.  Organic contaminants have been shown to decrease reproductive output (33).   Additionally, the spotted turtle is extremely sensitive to toxicity, and can die easily when exposed (34).  COSEWIC reports mention similar negative effects on the spiny softshell turtle and the wood turtle (2)(25).

If you remember my talk from Monday, these effects are good examples of habitat degradation.

What can I do?

  • Do you live in the Kingston area?  Do you frequent the Queen’s campus?  You may have noticed fish and frogs painted next to storm drains around the city.  This program, called “Fish and Frogs Forever”, is carried out by the Society for Conservation Biology.  It serves as a reminder to be weary of how you dispose of chemicals.  Runoff ends up right back in our aquatic systems.  In short, don’t be reckless with toxic contaminants.
  • If you are a nature lover, do not revisit turtle nests if you are so lucky to come upon one.  If you read my anecdote above, you will know why.  You could unknowingly be leading predators to these nests.
  • Let these animals be – if you see them in the wild, do not attempt to interact with them.
  • This one may be a bit controversial, but if you have a carnivorous pet, try not to let it run wild – especially if you live in an area with a lot of wildlife.
  • Keep in mind that most of Ontario’s turtles are very small!  They may be hard to see, so watch where you step when you are out there.
  • Try to limit motor activity near sites that have dense turtle populations.  Like I said, they are very tiny and hard to see, and are highly susceptible to harm by boats and terrestrial vehicles.
  • Tell people what you’ve learned!

References

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8 thoughts on “The wood turtle and the effects of human interactions

  1. That turtle looks awesome.

    So I am not allowed to take one out of its environment and keep it as a pet?

    So if we just left these turtles alone for decades, centuries, millenniums, etc. would their populate just re-regulate itself, or does threatened mean they need humans to do stuff to ensure the population doesn’t go extinct?

  2. no krishna, you can’t take them!
    hmm that second one is a good question
    it’s tough to answer because there are a lot of factors
    but i think the population hasn’t deteriorated to the point where it needs serious intervention
    i think if we left them alone they might have the chance to become successful again
    however, i still think that we would need to restore some of their natural habitat – and this is definitely a sketchy issue.

  3. This turtle looks like a squash, the kind that my mom buys and cooks for dinner.

    This may be slightly off-topic but do synthetic estrogens and androgens from human waste and pollution have any effect on the eggs and reproduction cycles of turtles?

  4. i just found one this morning in the road my daughter darted out of our car and rescued it from definate death now is hanging out with our red eared sliders in our yard pond do you think it was coming to the road to lay eggs???? i would love for this turtle to have some babies that would survive seeing its status in the north country is compromised

  5. Pingback: The Wood Turtle | Science

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