What causes deformities in frogs, toads, and other amphibians?

Malformed frogs first came to national attention in 1995. Since that time, reports of malformed frogs and other amphibians have increased dramatically. Malformations have been reported in at least 44 states and in more than 50 species of frogs and toads. Multiple limbs, missing limbs, and facial abnormalities are the main malformations seen.

Frog malformations are the result of environmental factors affecting development during early tadpole stages. The variations in malformation suggest multiple causes are involved in this worldwide problem; four major causes that have been identified include injuries from predators, a specific parasite (fluke), nutritional deficiencies, and contaminants.

Amphibians are good indicators of significant environmental changes. Amphibians, unlike people, breathe at least partly through their skin, which is constantly exposed to everything in their environment. Consequently, their bodies are much more sensitive to environmental factors such as disease, pollution, toxic chemicals, ultraviolet radiation, and habitat destruction. The worldwide occurrences of amphibian declines and deformities could be an early warning that some of our ecosystems, even seemingly pristine ones, are seriously out of balance.


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What is the United States doing about amphibian deformity and decline issues?

In response to indications of worldwide declines in amphibian populations, Interior Department agencies were directed to initiate a national program of amphibian monitoring, research, and conservation. There is an urgent need to determine the scope and severity of the problem and to investigate causes. As a result, the USGS formed the National...

How many amphibian species are there in the United States?

More than 6,000 amphibian species exist worldwide, with approximately 300 of them found in the United States. The USGS is the lead agency for the Amphibian Research and Monitoring Initiative (ARMI) , a program of amphibian monitoring, research, and conservation that was established in response to the worldwide decline of amphibian species.

Why are frog and toad populations declining? 

Research suggests that even though amphibians are severely declining worldwide, there is no smoking gun – and thus no simple solution – to halting or reversing these declines. Though every region in the United States has suffered amphibian declines, threats differ among regions. They include: Human influence from the Mississippi River east,...
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Date published: September 19, 2017

Emerging Disease Further Jeopardizes North American Frogs

A deadly amphibian disease called severe Perkinsea infections, or SPI, is the cause of many large-scale frog die-offs in the United States, according to a new study by the U.S. Geological Survey

Date published: May 23, 2016

New Research Confirms Continued, Unabated and Large-Scale Amphibian Declines: Local Action Key to Reversing Losses

New U.S. Geological Survey-led research suggests that even though amphibians are severely declining worldwide, there is no smoking gun – and thus no simple solution – to halting or reversing these declines.

Date published: February 22, 2016

Deadly Amphibian Fungus Abroad Threatens Certain U.S. Regions

The areas of the United States that are most at risk of a potentially invasive salamander fungus are the Pacific coast, the southern Appalachian Mountains and the mid-Atlantic regions, according to a recently published U.S. Geological Survey report.

Date published: May 22, 2013

USGS Study Confirms U.S. Amphibian Populations Declining at Precipitous Rates

The first-ever estimate of how fast frogs, toads and salamanders in the United States are disappearing from their habitats reveals they are vanishing at an alarming and rapid rate.

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Eft stage of red-spotted newt
September 27, 2016

Eft stage of red-spotted newt

The eft stage of a red-spotted newt.

Attribution: Ecosystems
An American bullfrog.
June 30, 2016

American bullfrog close-up

An American bullfrom is native to most eastern states, but considered invasive in the moutain west.