Amphibia Q&A

QUESTIONS AND ANSWERS

1. How do frogs hear?
2. I spend my summers at Matlock Manitoba. Over the summers I have noticed the frog population of Nothern leopard frogs and wood frogs has decreased. Yet this summer there was a huge increase. Has this happend in Minnesota too?
3. I catch frogs in the ditches near Lake Winnipeg in a cottage area. As the frog populations decreased I never saw a deformed frog and as the populations increased I never saw any either. Is it strange not to see any deformed frogs when the population is increasing? Or is it just really good news?
4. Why do frogs have nucleated red blood cells (RBC)?
5. If I wanted to start caring for some tadpoles now, how could I care for them in an aquarium? I live in the north west part of Minnesota and would like to have some frogs next spring. I believe that some tadpoles overwinter in my area. Can you help?
6. I have seen many frogs but never heard of any endangered frogs. Are there many endangered frogs?

QUESTIONS WITH ANSWERS

1. How do frogs hear?
Harris: Frogs hear in a similar way to the way that humans hear. However, a frog has a thin membrane called the tympanic membrane which can be flush with the side of their head and is located behing the eyes. They pick up sound waves in almost the same range as humans. I would recommend that people interested in this, read Duellman and Trueb's "Amphibian Biology" (1985).
Moriarty: Other books that discuss hearing in frogs are: Holmes "Biology of Frogs," Wever "The Amphibian Ear" (this is a major academic monograph).


2. I spend my summers at Matlock, Manitoba. Over the summers I have noticed the frog population of Nothern leopard frogs and wood frogs has decreased. Yet this summer there was a huge increase. Has this happend in Minnesota too? (Submitted by Ken McCullogh, Canada)
Moriarty: There are a number of reasons why frog populations fluctuate. The main one being drought. In Minnesota, in the mid-1980's we had a series of drought years which caused a major decrease in frog populations. The dried up wetlands limited breeding sites and the dry uplands caused increased mortality because of improper microhabitats (moist grass or leaf litter). Our frog populations have been increasing since 1991 and are back to normal levels.


3. I catch frogs in the ditches near Lake Winnipeg in a cottage area. As the frog populations decreased I never saw a deformed frog and as the populations increased I never saw any either. Is it strange not to see any deformed frogs when the population is increasing? Or is it just really good news? (Submitted by Ken McCullogh, Canada)
Moriarty: The presence or absence of malformed frogs is not tied into the population densities, but rather the habitat quality. While researchers do not know the exact cause, it is now thought to be caused by something in the water. You may be fortunate in not having this contaminant in the Lake Winnipeg area. You should know that, even though the news reports make it sound like most of Minnesota's frogs are malformed, most of our frogs are very normal and healthy.


4. Why do frogs have nucleated red blood cells (RBC)?
Harris: This is a good question, and scientists aren't sure. Nucleated RBCs means that the cells have a nucleus present in them. Some think that a better question might be "Why do some animals, like humans and birds, have non-nucleated RBCs?" A good source for frog-related anatomical questions is "Biology of Amphibians" by William Duellman and Linda Trueb (1985).


5. If I wanted to care for some tadpoles now, how could I care for them in an aquarium? I live in the north west part of Minnesota and would like to have some frogs next spring. I believe that some tadpoles overwinter in my area. Can you help? (Submitted by Cay Donlin, Thief River Falls, Minnesota)
Moriarty: In Northwest Minnesota the only frog that will overwinter as a tadpole is the Northern Leopard Frog. They can be raised in aquaria over the winter, but will go through metamorphis early, if they are fed and kept warm. You will end up with frogs in January!
It would be better to collect some Wood Frog or American Toad eggs in the spring and raise them. They grow rapidly and should go through metamorphis in early July.


6. I have seen many frogs but never heard of any endangered frogs. Are there many endangered frogs? (Submitted by Mike Harney)
Moriarty: Any endangered frogs are very rare and hard to find. In Minnesota, there is one endangered species, the Blanchard Cricket Frog. In the United States there are a number of species. Two include the Houston Toad and Wyoming Toad. There are several species in California. For further information you should check the US Endangerd Species List published by the Fish and Wildlife Service. Species from other countries can be found on the CITES list.