We loved our hike at Tiny Marsh but I did not expect the amount of destroyed turtle nests we saw.
Without realizing what was happening Josh had seen a female laying her eggs the day before. Notice the algae all over her shell. This occurs because she spends most of her time under water and it helps provide camouflage.
I had missed the sign at the front and first thought that the eggs had hatched. I believe these are snapping turtle nests but I might be wrong.
Snapping Turtles are listed as “of special concern” in both provincial and federal endangered species legislation. They are Canada’s largest freshwater turtle and won’t start breeding until they are 15 to 20 years old.
Because Snapping turtles can live between 70 and 100 years the turtles we see in our lakes and wetlands may have hatched and started breeding before World War II.
Snapping Turtle Population Collapse?
Since they live for so long, and take so long to start breeding, the turtles we see now may all be very old. Extreme nest predation could mean that there may come a time when all of the older turtles die off and there aren’t many left to replace them.
Adult turtles don’t have much to worry about other than humans and human related threats. Turtle mortality is high during nesting time when females, forced by loss of habitat, must cross roads and are often hit by cars.
Suitable nesting sites in nature are usually gravelly or sandy areas along streams. Man-made structures including roads (especially gravel shoulders), dams and aggregate pits are being used more frequently because of habitat loss but at a cost.
Threat to Eggs and Hatchlings
Eggs are a rich protein source. Raccoons have been observed waiting for a female to lay her eggs and then immediately excavating the nest and consuming the eggs. Other predators such as minks, foxes and skunks do a good job of eating every last egg. Observations around Ontario have shown 100% nest predation in a given area.
Hatchlings have to deal with new predators – herons, bullfrogs and large-mouth bass, as well as invasive species, such as Common Reed grass, which blocks their path to the water.
A female will lay an average of 20 to 40 eggs per nest, 1400 in her lifetime, just for one of her offspring to survive to adulthood.
Studies have suggested that even a 10% increase in adult mortality in a snapping turtle population would result in the disappearance of half of that population in less than 20 years.
Fun Fact: The sex of hatchlings varies depending on the temperature that eggs are incubated at. Eggs that are kept at a temperature of 23-28°C hatch male turtles. Eggs incubated at other temperatures hatch into females.
What can you do?
- Watch for turtles while driving, especially between May and October. They are slow, they can’t get out of your way.
- Submit your sightings to the Ontario Reptile and Amphibian Atlas www.ontarionature.org/atlas.
- Protect any wetlands and surrounding natural vegetation that you already have on your property and perhaps add some more.
- Adopt a Pond through the Toronto Zoo www.torontozoo.com/Adoptapond
Books I Want to Read
The ROM Field Guide to Amphibians and Reptiles of Ontario by Ross McCulloch and the Royal Ontario Museum
Part 1 on the Black Tern in Tiny Marsh
Part 3 on Mushrooms in Tiny Marsh