I have really enjoyed watching the frogs at my water feature this year, happily assuming I knew what they were – Green frogs (Rana clamitans melanota). However as the summer went on it became obvious one was not like the others. Turns out she’s a Bullfrog (Rana catasbeiana). By the way, Scientific Latin + auto spell check = nightmare. There is a trick to telling them apart, besides the size difference, which is only helpful when you can compare them. Green frogs have a dorsal lateral ridge a raised line that begins at their eye and runs down their back. Don’t be confused by the black markings which go around his eye (I believe these markings vary from frog to frog).
The Bullfrog not so much ridge, you can see her’s starts at her eye and goes around her ear (tympanum).
I refer to the Bullfrog as female because the male of both species has a yellow throat and the one above has a whitish one. The photo below shows the color difference in Green frogs.
Male Green frogs reach sexual maturity at one year of age and females at two or three, seems a bit unfair to me. Bullfrogs don’t reach sexual maturity until four or five and take two to three years to develop from egg to frog – that’s a long time as a tadpole.
Here are some photos that clarify the size difference.
The bars are 3.5 inches apart and the cedar plank is 6 inches wide, essentially Green frogs are as long as Bullfrogs are wide. Well, at least are/were.
More fun facts can be found at Rhode Island Vernal Pools. All the information in this post should be credited to them, any mistakes to me. It’s a very neat site, lots of cool ecology info.