Creature Feature: Toro Toro

A few weeks back, one of our awesome naturalists and lead newsletter editor took a vacation to the state of Montana and got to see some incredible sights. One of these sights included being in the presence of the American bison, a large bovine that is symbolic to many, and once upon a time had an abundant and dominant presence throughout much of North America. There are some records of male bulls weighing thousands of pounds! Here is some drone footage of bison crossing a stream taken during her trip.

We have our own kind of bulls here at the Johnson Nature Center too! Continue to scroll down to find out what they look like

Wait for it….

Ta daaa!

Apologies for the bamboozle, I couldn't resist. Yes, this month’s creature feature is about the American bullfrog! The largest frog species in all of North America, bullfrogs can grow up to six inches long from its snout to its ventral end. Although they are a North American species, they are only native to the eastern side - from the coast of the Atlantic Ocean to the Great Plains. However, they have also been introduced west of the Rocky Mountains and to several other countries as well.

One of the ways you can tell the difference between a male and a female bullfrog is by the color of their throat. Males have a yellow throat, while females have a white-cream colored throat. Right before their breeding season (early, mid summer) the males will claim a territory along or around the wetland that is about 3-6 meters wide. Their call sound is not like the classic “ribbit” frog call that we all know, but rather, in my opinion, sounds like something more akin to a bellowing bear.

Bullfrogs prefer to inhabit wetlands and other water bodies that stay permanent throughout the year, such as swamps, lakes, and ponds. To avoid predators, they rely on a number of abilities. One is that their legs are modified so that they are able to jump 10x their body length. A second defense that bullfrogs have is a large round shape near their head and eyes called a tympanum - a structure that aids in hearing that often goes by the nickname “Ear Drum”. For frogs, it’s a circular membrane close to the eyes that vibrates when sound waves hit the structure. This is a key feature for many animals that results in them being able to interpret sound.  Humans have one also, but it is located deep within our ear canal where we are unable to see it.

That’s me showing off the legs of a bullfrog to 5th graders during an ecology-themed field trip. The class named it Jerome. Maybe the next one we find can be dubbed Jeremiah. 

One last fun fact about the American bullfrog: while there are illnesses that affect animals all around the world, these frogs are mostly immune to a specific fungal disease found only in amphibians called chitro……chitri……(checks notes)... chytridiomycosis. The fungus that causes this condition targets the skin of amphibians, and since skin is one of the primary ways an amphibian performs respiration, it can make breathing for the infected difficult. Although bullfrogs are immune to infection, they still remain a cause of concern as they could potentially spread the fungus to more susceptible frogs.

If you are walking one day around a wetland be on the lookout for these beasts of amphibians!

Click here to learn more about the American bullfrog

Submitted by Zach Mork, Naturalist, June 2022