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The Life and Loss of Frogs

The Difference Between Frogs and Toads Many people are surprised to learn that toads are frogs. These amphibians are mainly differentiated by their skin texture; frogs tend to be smooth or slimy while toads have a drier, sometimes warty skin.  Though there are other distinctions, the one thing they most certainly have in common is that they are decreasing in populations all over the world.  Frogs and Toads of Indiana American toad Bird-voiced treefrog Blanchard's cricket frog Bullfrog Cope's gray treefrog Eastern gray treefrog Eastern spadefoot toad Fowler's toad Green frog Green treefrog Northern crawfish frog Northern leopard frog Northern spring peeper Plains leopard frog Pickerel frog Southern leopard frog Western (striped) chorus frog Wood frog *Information found at the Indiana DNR.

It is said that frogs have an easy life as they can eat what bugs them. Unfortunately life isn't all that easy for our four-legged friends. Recent findings have shown that frogs and other amphibians - toads, salamanders and caecilians - have drastically declined in population over the past several decades.

The Year of the Frog

For many zoos, aquariums and conservation organizations, 2008 is the Year of the Frog. Why? Besides being historically intriguing  creatures, frogs are possibly facing the largest mass extinction since the disappearance of dinosaurs. 

According to the World Conservation Union (IUNC) nearly 32% of all amphibian species we know of are in danger of becoming extinct. Amphibian populations have fluctuated widely throughout our history, but the fact that declines have been so widespread  lead scientists to believe that something was seriously amiss.

In 2004, a global amphibian assessment was made and results were more worrisome than first thought. Besides learning that almost one-third of our 6,316 (and counting!) amphibian species were in danger of extinction, it was also found that at least 43% of all species are declining in population and as many as 165 species are already extinct. 

For a more complete analysis of the Global Amphibian Assessment, check out NatureServe's "Disappearing Jewels: The Status of New World Amphibians."

Chytridiomycosis and Other Treats to Frogs and Toads

One of the biggest threats to amphibian populations is the highly  infectious disease Chytridiomycosis. Chytridiomycosis is caused by the amphibian chytrid fungus, Batrachochytrium dendrobatids. The fungus can be found in water, soil and as parasites in plants and animals. The sudden impact of the fungal disease leads scientists to believe that Chytridiomycosis was introduced to the affected environments, though the origin of its existence is still unknown.

What we do know is that the disease affects the skin, a vital organ through which many frogs and toads use to breathe and drink. There are also no treatments or methods to rid the fungal disease from the cool climate environment it prefers. In fact, Batrachochytrium dendrobatids may be found naturally in the wild. How long it has been killing amphibians and how it spreads into populations all over the world is still sketchy.

Chytridiomycosis is not the only threat facing frogs and toads. Habitat loss, pollution, pesticide drift, invasive species and other amphibian diseases are also to blame for the decreasing numbers of frogs and toads worldwide. Climate change is also an issue, albeit a controversial one. In 2006, a group of researchers declared that global warming was the "trigger" to the recent mass extinctions of frogs; the "bullet" being the chytrid fungal disease. In March 2008, another set of researchers argued that the mass die-offs were solely due to chytridiomycosis. There is no telling who is more correct

Why We Should Care and What We Can Do to Help

Frogs and toads play an important role in nature. As both predator and prey, these species help sustain the delicate balance necessary in whatever ecosystem they dwell in. As eaters of pests, they benefit agriculture and help minimize the spread of diseases such as malaria.

They are also incredible biological indicators of our environment's health. Considered "canaries in the coal mine," frogs are among the first species to be affected by environmental stressors. Their decline in the wild is seen as a warning to other species - including humans - and should be taken seriously.

Thankfully it is and Hoosiers are already leaping into action! Indiana's North American Amphibian Monitoring Program and Frogwatch USA are just two programs that allow Hoosier's to participate in monitoring the numbers of frogs and toads in our state. Keeping track of these amphibians give us that early warning about possible environmental dangers we need to know about. Volunteers are always needed, so check these programs out! Lessening your carbon footprint and supporting land conservation groups are other ways to help.

For more information

AmphibiaWeb - an online system that allows free access to information on amphibian biology and conservation.

USGS Checklist of Amphibian Species and Online Identification Guide

LivingUnderWorld - a web project all about amphibians.

More information on frogs and toads can be found at the Amphibian Conservation Alliance.

Amphibian Arc - a site filled with information about "Year of the Frog 2008" and what we can do to help keep our "threatened amphibian species afloat!"


 

Nature picture credits (top to bottom, left to right): Photo © Paul Thomas (Northern leopard frog); Photo © Indiana DNR (spring peeper).