Endangered Frogs

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Updated on Aug 20, 2013

Amphibian populations are in global decline. Because the skin of amphibians like frogs, toads and salamanders is extremely sensitive to environmental changes, there has been much speculation that the die-off is due to the effects of global warming. In spite of the global nature of the die-off, however, there does not seem to be one global factor behind it. As a result, local conditions have also been called out as possible contributing factors. These include the introduction of predators or competitors, acid rain, unfavorable weather patterns, environmental patterns, and infectious diseases.

This project seeks to identify conditions responsible for the at-risk status of threatened or endangered frogs in the region where the student lives.The project is of a theoretical nature, and requires the student to consult experts and published literature to obtain data. The goal is to have the student develop and test a hypothesis that attempts to explain why a particular frog species is in decline and another is not.


Why are some frog speciesendangered, but others are not?

  • Computer with Internet access
  • Access to a library
  • Experts on the subject

  1. Conduct a review of the published literature describing the global status of amphibian populations.
  2. Formulate a hypothesis that attempts to predict whether frogs in the region where you live will be threatened with extinction.
  3. Consult a list of threatened and endangered frogs in the U.S. and identify an at-risk frog in the region where you live. See, for example, http://sites.hamline.edu/cgee/frogs/science/Threatened.pdff.
  4. Make a list of factors that might be contributing to the decline of the frog.
  5. Prepare a table that calls out any local conditions that may be contributing to the population decline. For example, if loss of habitat is a suspected factor, the fact that new roads have been built in the area will be relevant.
  6. Attempt to identify a frog population has remained relatively stable in another locale. Try to select a frog species related to the one you have been tracking or one with a traditionally similar habitat.
  7. Prepare a second table analogous to the one you prepared for the first frog.
  8. Compare the two tables, noting any major differences. Then evaluate, and if necessary revise, your original hypothesis to accommodate your findings.
  9. Propose mitigations that might be taken to protect the at risk frog.

The following table (taken from http://www.solcomhouse.com/frogs.htm) might serve as a template for data collection in this experiment.


Habitat destruction, alteration and Fragmentation

Roads, introduced species, or other factors separate remaining populations of amphibians from each other

Introduced Species

Non-native species prey on or compete with native amphibians


Amphibians are removed form the wild and sold internationally as food, as pets, or for medicinal and biological supply markets

Climate Change

Amphibians are extremely sensitive to small changes in temperature and moister. Changes in global weather patterns (e.g. El Nino events or global warming) can alter breeding behavior, affect reproductive success, decrease immune functions and increase their sensitivity to chemical contaminants.

UV-B Radiation

Levels of UV-B radiation in the atmosphere have risen significantly over the past few decades. Researchers have found that UV-B radiation can kill amphibians directly, cause sublethal effects such as slowed growth rates and immune dysfunction and work synergistically with contaminants, pathogens and climate change.

Chemical Contaminants

Chemical stressors, such as pesticides, heavy metals, acidification and nitrogen based fertilizers, can have lethal, sublethal, direct and indirect on amphibians. Some of these include death, decreased growth rates, developmental and behavioral abnormalities, decreased reproductive success, weakened immune systems and hermaphroditism.


A combination of new diseases or more susceptible amphibians leads to deaths of adults and larvae


There has been a recent increase and widespread occurrence of deformities (or malformations) in natural populations of amphibians and has recently been perceived as a major environmental problem.


Multiple factors can act together to cause mortality or sublethal effects.

Dr. Frost has been preparing curriculum materials for middle and high school students since 1995. After completing graduate work in materials science at the University of Virginia, he held a postdoctoral fellowship in chemistry at Stanford. He is the author of The Globalization of Trade, an introduction to the economics of globalization for young readers.

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