At Alderleaf, we have many native amphibian species appearing in healthy numbers. As of last year, we first noticed a bullfrog had shown up in one of our ponds. The bullfrog (Rana catesbiana
) was a very large individual, and it likely overwintered in that little pond. Bullfrogs are not native to the West coast, but have been extensively introduced. They prey on many of native animals, including our native amphibians.
Some people are very strongly against the bullfrog, and want to see it eradicated. Although, bullfrogs by themselves are probably not responsible for the serious decline of many amphibians in the USA, they are an additional factor that might compound the more serious threats of pollution, introduced disease agents and habitat loss.
They are legally hunted without a permit in WA state, and have no season or bag limit. It so happens, bullfrogs are also good to eat. The is part of what encouraged their introduction in the first place, since they are much larger and produce much bigger frog-legs for the market than any of our native West coast frogs.
Since at Alderleaf, we really want to do whatever we can to help support the health of native animals, we want to control the presence of bullfrogs on the property.
Northern red-legged frog (Rana aurora
) are a large, native species that is endemic to the moist, coastal forests and adjacent wetland habitats of the Pacific Northwest. It has experience considerable decline in some areas. They appear to be doing relatively well at Alderleaf.
I remembered that I had the opportunity during a wetland restoration project to compare the 2 species side by side. It so happens I had a camera on me at that time. Here they are...
These two frogs are likely close to the same age and definitely both juveniles. Notice the differences between them. The red-legged frog has a more pointed head, less upward angled eyes (eyes angle more directly to the sides), a pale line on the upper lip that runs to just behind the eye. A flesh ridge runs from the back of its eye to its rump, on each side of its body. Meanwhile, the bullfrog has more upward facing eyes, a less pointed face, and a ridge/fold of flesh that runs from behind the eye to the front of the foreleg. No fleshy ridge on its back running from eye to rump.
Now, notice the distinct inner thighs and inner legs of the aptly named red-legged frog. Notice how much paler the bullfrog legs appear.
Though these 2 individuals look quite different from each other, they can appear much more similar in color especially in older animals. This can cause some confusion.