Jeff Corwin Field Reports

Read Jeff Corwin's special reports from the field as he traveled to uncover clues on the frog's deadly plight.


by Jeff Corwincorwin report

I've been lucky for most of my life because I've had the opportunity to come to places like this stunning wilderness in the Sierra Nevada. When I was growing up, my father was a Boston police officer and worked sometimes 80 hrs a week, but he would find time for me in his busy schedule to take me away from the city to explore nature. We used to catch tadpoles and bring them home to watch them metamorphose into frogs. I think I do what I do today because of having those symbolic experiences in my childhood, and frogs have always held a special place in my conservation efforts.

Two days of horseback riding (and a sore rear end from time in the saddle), our journey took us through two national parks, from pine forest to alpine habitat, from 6,000 feet above sea level to our final destination at 11,000 feet. Biologist Vance Vredenburg greeted us at the remote and pristine high elevation wilderness known as 60 Lakes Basin. Vance has been studying rare California Yellow Legged Frogs in this region for more than five years. The frog population has been steadily declining, but it seems he has pinpointed two main factors; non-native fish in the region and the elusive chytrid fungus are wiping out throngs of frogs.

To increase fishing in the area, trout, a non-native species, were introduced the 1950s, first grown in hatcheries and then dropped by airplane into the lakes. Frogs, which had no real predators, widely populated the many lakes. When trout were introduced, they went right for eating tadpoles, which were basically helpless. In order to stave off the eradication of the frogs, scientists simply began removing the trout from the lakes. Within a year, the frog population had rebounded.

Now, however, there is a new predator that is wiping out the frog populations. The chytrid fungus is sweeping through, lake by lake, and literally wiping out the Yellow Legged Frog populations. Professor Vrendenburg developed a process to collect infected frogs and treat them one by one by removing the deadly fungus. By using microtags placed on the frogs, he has been able to track the populations of previously infected frogs that have been treated and now released back into the wild.

The entire region has been reduced from hundreds of lakes of frogs to one remaining stronghold. Thousands of frogs are now down fewer than 200. Chytrid comes almost like a tsunami and wipes out these frogs, and animals that depend on them for energy and survival no longer have a resource.


by Jeff Corwincorwin report

The Hellbender Salamander is another amphibian that's been grossly affected by chytrid. Here at the St. Louis Zoo, they're attempting to do what no other zoo has ever endeavored before. They're trying to breed a Hellbender in captivity.

I joined herpetologist Jeff Briggler, with the Missouri Department of Conservation, and colleagues Jeff Ettling and Mark Wanner on a wild goose chase, or salamander rather, to locate one of these incredible creatures. Due to a perfect storm of habitat changes, bad water quality, and our elusive fungus, their population is down 80% in Missouri; but that's not the only thing declining. It turns out that the sperm count is also low, not only for these salamanders, but for the male human population of Missouri as well. Theories point to the chytrid fungus as being the perpetrator. We were extremely fortunate to catch an 18-inch long Hellbender, which was an amazing find! After swabbing for chytrid and checking its overall health, we tagged the animal so we can keep an eye on him in the future, and then released him back into his river.

At the zoo, they've constructed a 32-foot stream and environment for the Hellbenders to live in. Though no one has yet been able to breed a Hellbender in captivity, the theory is to provide them with an ideal breeding situation. Here they have an abundance of food, correct temperature and photoperiod. The salamanders still have yet to breed, so the zookeepers have brought in juveniles from the wild to raise here in captivity. But even in captivity the Hellbenders aren't completely safe. Some of the juveniles became affected with chytrid and it seemed there was no way to remove it without harming the salamanders. However, through a pioneering idea, they were actually able to save all the salamanders. To kill off the chytrid, they slowly raised the temperature of the water to 90 degrees, hot enough to cook off the fungus but not to harm the Hellbenders.

These indicator species tell us the environmental state of an ecosystem, and just in that fact alone they're so important. Three years ago, the Hellbenders were given 20 years left before becoming extinct. Thanks to the hard efforts of the St. Louis Zoo, these salamanders may have a new lot on life, and will hopefully be around for years to come.

corwin report 2


by Jeff Corwin

Another non-native species seems to be the cause of trouble for amphibians, and this time it's actually a frog. African Clawed Frogs may be the carriers of t`he deadly chytrid fungus that's wiping out the rare California Yellow Legged Frog. But what are they doing in America? It turns out that in 1934 these frogs were discovered as a reliable way to detect if a woman was pregnant. The woman's urine was injected into the frog, and if the frog started ovulating, the woman was determined pregnant. Because of this find, millions of these frogs were transported all over the globe. Unfortunately, they lived in an environment exposed to the chytrid fungus. Immune to the fungus themselves, the African Clawed Frogs carried the fungus with them wherever they went.

From the California Department of Fish and Game, I met up with Eric Larson, who was actively removing thousands of African Clawed Frogs from ponds in the area. As a conservationist, seeing the effect that these frogs had on the environment was devastating. They were most likely released to the wild either intentionally or inadvertently; many frogs were used in laboratories for experiments, but also as pets. Every parent wants to have their kid release their goldfish or turtle or pet frog, and it's a real problem. It can truly annihilate the native fauna in ponds like this and it can also spread to other locations.

People like Larson and his crew are slowly eradicating the expanse of the frog and fungus associated with it, a little at a time. It's just one angle to amphibian conservation and one of the many reasons why we need to protect frogs. Not only are they good for the environment, for biodiversity, and for ecology, but these creatures are tremendously helpful for human beings as well.

I traveled to the University of California, Berkeley, where Professor Tyrone Hayes, enlightened me on the importance of frogs for scientific and medicinal purposes. Here he was studying the effect of a chemical called atrazine, a pesticide used widely in agriculture to kill weeds, on the African Clawed Frog. The studies show that atrazine creates a hormonal imbalance that can actually transform the frog's sex from male to female by overloading its estrogen levels. But the real scary part is that the approved levels of the chemical percentage allowed in drinking water are actually higher than the levels needed to cause this radical change in the frog.


by Jeff Corwin

As a naturalist and conservationist, I find it incredibly alarming and odd to walk into what appears to be a vibrant rainforest only to find it eerily silent. Such is the case in this remote tract of jungle in the Omar Torrijos National Park in central Panama. The cacophony of calling frogs, which filled the tropical air here just a year or so ago, no longer echoes throughout this forest.

Along with biologists Bill Konstant and Edgardo Griffith of the Houston Zoo, I attempted to find any last remaining traces of the Harlequin frogs, considered by many within the conservation community to be extinct in the wild. The Harlequin frogs are disappearing not only from Panama, but the entire planet, as a result of a perfect storm of extinction – habitat loss, pollution, climate change, and unsustainable exploitation. In addition, the chytrid fungus, which originated in Africa and has now spread throughout the planet, is wiping out many species of amphibians. It is having a particularly devastating impact on the frogs, toads and salamanders of the Neotropics.

It is an extraordinarily humbling experience to realize that there are species we have come across in our own lives (in my case, many of which have been featured on my own television series on Animal Planet) that are now extinct. Incredibly though, the improbable JUST may have turned possible in Panama. After an exhausting trek and search through nearly impenetrable jungle, all our hopes and hard efforts paid off. Our team found a juvenile female Harlequin frog along with 12 tadpoles! These incredibly rare and valuable specimens, which could very well represent the last of their kind, were carefully transported back to the El Valle Amphibian Conservation Center in Panama, where they will participate in a captive breeding program aimed at eventually reintroducing the species back into the wild.

The discovery of these amazing frogs was just one of many incredible moments my film crew, my fellow conservationists, and I experienced while in Panama. From here we will move on to Ecuador, then through America, and finally Australia as we explore the conservation crisis that is destroying an iconic class of vertebrates that could very well disappear within our lifetime.

© 2008 The Clorox Company. All Rights Reserved | Terms of Use | Privacy Policy