The American Bullfrog, an introduced species to British Columbia and to Vancouver Island, poses an increasingly serious threat to several native species. Quite recently one was found here on Denman Island. This particular individual was picked up by an alert resident living on Northwest Road. When it was found it was inhabiting a small pond on her property.It is entirely possible that there may be more of them on the loose. They are quite easily identified. A greenish colour and a very large size might be the first clues. They also have a very deep and very loud voice and produce the classic jug-o-rum, jug-o-rum call. You will know it if you hear it.
The visual identifier is its large tympanum, or ear drum, located behind and below the eye. It is quite visible and is at least as large as the eye itself. As you can see in these photos the frog also has a lateral fold which runs from the eye back over and around the tympanum. Other frogs have lateral folds but all of them simply run straight from the eye and down the back of the frog, only in the Bull Frog does it curve around the tympanum. And, of course, the first key give-away is its sheer size. It is much bigger than any of our native species.
These frogs represent an extreme threat to several other species on our island. In particular, the endangered Red-legged Frog would be prime prey as would Tree Frogs. They also quite happily eat young ducklings, other small birds and basically anything they can get their very large mouths around.
If you find one please contact Dennis Forsyth at 335-1146, Peter Karsten at 335- 1640, or any other member of the Wildlife Advisory Committee.
