Green Frogs Along the Bog

Our week in the Cape Breton Highlands National Park was excellent. Waterfalls, blueberries, mountains, beaches, bogs and the massive Atlantic Ocean were all welcome sights during our time collecting. There were no moose this time around, though I was equally gratified seeing an abundance of amphibians; particularly frogs and salamanders.

Can you guess the gender of the Green frog in this photo by the size of the tympanum?
Can you guess the gender of the Green frog in this photo by the size of the tympanum?

While conducting some aquatic sampling along the Bog trail, we came across many rather large Green frogs (Rana clamitans) and their tadpole counterparts. The crew was excited, these were the first Green frogs we had seen so far on the BIObus. The Green frog can grow to an upper length of about 4 inches, with the females tending towards the larger of the two sexes. A more direct way to distinguish between the two genders of Green frog is the size of the structure just below the eye: the tympanum. Males have a tympanum roughly twice the diameter of their eye whereas females possess a tympanum of equal diameter to the eye. As the tympanum is responsible for producing the Green frog’s distinctive call through vibration of the structure, the male’s larger tympanum is not a surprising trait given how vital producing a loud ‘croak’ noise is for males to defend their territory and to claim mates.

The Green frog is found all across North America in great abundance ranging from Florida to Newfoundland, their populations typically large and stable. The females release a massive egg clutch for fertilization, with 1000-7000 eggs being deposited at a given time. The eggs will mature to tadpoles, which will either mature to an adult form in the current season or overwinter in preparation for the next.

Now that we have arrived in Kejimkujik National Park, the herptofauna capital of Atlantic Canada, I imagine we will see many more Green frogs along our arthropod collecting journey.


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