03/11/12

Become a FrogWatch USA Volunteer: Listen to your Local Frogs

In the U.S., frogs and toads are beginning to wake up from their winter hibernation and soon we’ll be hearing the calls of spring as the amphibian breeding season begins. This a great time to become a Frog Watch USA volunteer, where you will make a commitment to monitor a local site for 3 minutes at least twice a week throughout the breeding season.

You don’t have to be an expert to become a volunteer, but you might find it helpful to attend a Frog Watch training session hosted by zoos, aquariums, and conservation organizations nationwide. Here’s a list of the upcoming training sessions:

Connecticut
Yale Peabody Museum of Natural History
March 16, 2012; 6:00-8:00 pm
March 20, 2012; 6:00-8:00 pm

Florida
Brevard Zoo
April 11, 2012; 4:30-8:30 pm
April 14, 2012; 4:30-8:30 pm
May 23, 2012; 4:30-8:30 pm
June 20, 2012; 4:30-8:30 pm
July 25, 2012; 4:30-8:30 pm
August 22, 2012; 4:30-8:30 pm
August 25, 2012; 4:30-8:30 pm

Santa Fe College Teaching Zoo, Gainesville, FL
March 17, 2012

Tampa’s Lowry Park Zoo
April 5, 2012; 6:30-8:30 pm (volunteer training)
May 3, 2012; 6:30-8:30 pm (call identification and certification)
June 7, 2012; 6:30-8:30 pm (volunteer training)
July 5, 2012; 6:30-8:30 pm (call identification and certification)
August 2, 2012; 6:30-8:30 pm (end-of-season wrap up/pot luck)

Indiana
Fort Wayne Children’s Zoo
March 13, 2012; 5:30-9:30 pm
March 17, 2012; 1:00-5:30 pm

Monroe County Parks and Rec
March 22, 2012; 6:00-9:00 pm

Michigan
Detroit Zoo
March 11, 2012; 1:00-4:00 pm
March 18, 2012; 1:00-4:00 pm

Missouri
Saint Louis Zoo
March 24, 2012; 10:00 am-12:30 pm
March 28, 2012; 7:00-9:00 pm (certification)

New Jersey
Jenkinson’s Aquarium
March 21, 2012; 6:00-8:00 pm

Rhode Island
Roger Williams Park Zoo
March 24, 2012; 10:00am-12:00 pm
April 12, 2012; 6:00-8:00 pm

Tennessee
Chatanooga Zoo
March 31, 2012

Utah
Utah’s Hogle Zoo
March 17, 2012; 2:00-4:00pm

Virginia
Virginia Zoo, March 18, 2012; 5:00pm

At a recent training session at the Lynchburg (VA) Public Library, for example, volunteers listened to the calls and then tried to connect them to a recognizable sound. Here’s one of the frog calls these volunteers tried to identify. Does the call of this Pickerel frog sound to you like a squeaky door – or like a snore?

More information:

The FrogWatch site includes a Frogs and Toads by State list and a link to the U.S. Geological Survey Frog Quiz of frog calls.

01/13/12

World's Smallest Frog Discovered

Researchers have discovered two species of what may be the world’s smallest frog species. As described in the journal PloS ONE, these new species of mini, terrestrial frogs were found on the island of New Guinea, and represent not only the smallest known frog but possibly also the smallest known vertebrate species (animal with a backbone).  Both new species are members of the recently described genus Paedophryne, the four species of which are among the ten smallest known frog species. They attain an average body size of only 7.7 mm (range 7.0–8.0 mm), less than the size of an M&M.

Photo courtesy Louisiana State University/PloS ONE

The researchers believe that the frogs have evolved their teeny size in a unique ecological niche: the leaf litter of tropical forests that remains moist year round. The frogs eat even tinier creatures (mites etc) that most other frogs don’t exploit. They are well camouflaged among leaves on the forest floor, and have evolved calls resembling those of insects.

According to the researchers, other places in the world that also feature dense, moist leaf litter tend to possess such small frog species, indicating that amphibians are well placed to occupy this ecological niche.

Before the Paedophrynes were found, the title of “world’s smallest frog” was bestowed on the Brazilian gold frog (Brachycephalus didactylus) and its slightly larger Cuban relative, the Monte Iberia Eleuth (Eleutherodactylus iberia). They both measure less than 1cm long.

For more information:

Rittmeyer EN , Allison A , Gründler MC , Thompson DK , Austin CC , 2012 Ecological Guild Evolution and the Discovery of the World’s Smallest Vertebrate. PLoS ONE

10/9/11

Winter is Coming: How Do Frogs Avoid Freezing?

Yesterday while shopping at the mall, I noticed that some stores had already begun putting up holiday decorations. The racks were filled with sweaters and down coats. We humans (at least in the northeast U.S.) are preparing for winter. But what about our amphibian friends? How do they prepare for winter? After all, frogs would seem vulnerable to extreme cold with their thin skins and their need to constantly stay moist.

Actually, we don’t need to worry about the frogs. They are well-equipped to deal with the cold weather, even with Arctic temperatures.

Frogs are ectothermic, which means that they rely on their environment to regulate their body temperature. Birds and mammals, including humans, are endotherms. We generate heat chemically and internally by breaking down food. The bodies of ectotherms reflect the air, ground, and water temperatures around them. One advantage that ectotherms have over mammals is that they can survive for long periods without eating.

In the fall, frogs first need to find a place to make their winter home, a living space called a hibernaculum that will protect them from weather extremes and from predators. The frog then “sleeps” away the winter by slowing down its metabolism. When spring arrives, it wakes up and leaves the hibernaculum, immediately ready for mating and eating.

Aquatic frogs and toads such as the leopard frog and American bullfrog usually hibernate underwater in streambeds or on pond bottoms. Because aquatic frogs need oxygen, they lie just above the mud, or only partially buried in the mud, so they are near the oxygen-rich water. They may even occasionally slowly swim around.

Terrestrial frogs and toads typically hibernate on land. Those frogs and toads that are good diggers like the American toads burrow deep into the soil, safely below the frost line. Other frogs, such as the wood frog and the spring peeper, aren’t good diggers and so must scout out their winter homes in deep cracks and crevices in logs or rocks, or they might dig down into the leaf litter.

These frozen peepers and wood frogs might look dead; their hearts have actually stopped beating. But the partially frozen frogs aren’t dead. Instead, they have a kind of natural anti-freeze in their bodies. Ice crystals form in their organs and body cavity, but a high concentration of glucose in the frogs’ vital organs prevents freezing. When spring approaches and its hibernaculum warms up above freezing, a frog’s frozen body will thaw, and it will come back to life.

As you go about preparing for winter, think of the frogs with their amazing adaptations for survival, safe in their winter homes, waiting for spring.

Here’s a video from YouTube about the hibernation of a wood frog. It’s pretty amazing—take a look!

This is a partial repost of an earlier post from December 2010. Most of the information from the post came from an article in Scientific American, How Do Frogs Survive the Winter? by Rick Emmer.

08/29/11

Back to School: Thoughts about Grow-a-Frog Kits in the Classroom

Tadpole Metamorphosizing into Frog

It’s back-to-school time again, a time when teachers may be planning their life science classes. What better way to illustrate an animal’s life cycle than by teaching kids about the remarkable transformation of a tadpole into a frog?  Unfortunately teachers may decide to use grow-a-frog kits to teach children about metamorphosis.

I have to admit I have mixed feelings about advising teachers not to raise live amphibians in the classroom. As a child, my love of animals was fostered by the various animals I kept at home, including fish and turtles. I probably would have enjoyed having a live frog in the classroom.

But the authors of an article in the Herpetological Review, “Considerations and Recommendations for Raising Live Amphibians in Classrooms,” remind us that the world is no longer a simple place: innocent acts like catching tadpoles and releasing them later into local ponds are much more complicated than they used to be.

Releasing live  frogs “grown” in the classroom into the wild can potentially harm native amphibians (even if the animals are native to the area) by possibly spreading infectious diseases, such as the deadly chytrid fungus, a disease that has wiped out entire frog populations. It may also introduce species (such as bullfrogs) that might become invasive and disrupt local amphibians.

After we wrote a few posts discouraging people from buying the Frog-o-Sphere kits, quite a few readers who owned the kits were distressed and emailed us, asking  if they should “let the frogs go.” We wrote back immediately, telling them not to release the frogs into the wild. Instead we referred them to frog care sites and books. If you’ve already purchased a frog kit, it is your responsibility to take care of the frog. Releasing it into the wild helps neither the frog nor the environment.

The problems with the classroom grow-a-frog kits are similar. After the tadpole grows into a frog, the children may become bored with it and the teacher may decide to release it into a local pond. Or at the end of the school year, the teacher may give it to a family, who then releases it somewhere in the neighborhood.  As advised in the article above: “This should never be done, and in fact, it is illegal in several states. No amphibian purchased or received from any commercial or informal (e.g., a neighbor) source may be released into the wild. This recommendation applies whether the species is technically ‘native’ to the region of release, or not.”

If you decide to purchase a grow-a-frog kit (which we hope you don’t), you will be making a commitment to take care of the frog for its natural lifespan.

How can teachers and parents teach children about the life cycle of frogs without raising live frogs? We would suggest contacting a local nature center and setting up a field trip in the spring, where the children can see eggs and tadpoles in the wild.  This past spring while hiking I frequently saw frog egg clusters in ponds and swamps, and it’s fairly easy to see tadpoles as well. A local naturalist will know where to look.

To prepare the children for what they might see in the spring, here are some resources:

The Amphibian Project : Classroom curricula, field projects and hands-on activities, fundraising ideas for students, and links.

Amphibians. 35 min. (Eyewitness DVD) Describes amphibian life cycle and anatomy; behaviors and adaptations; and amphibian characteristics. Grades 5-12

Two frog life cycle plastic sets:

For more information:
Joseph R. Medelson III et al. “Considerations and Recommendations for Raising Live Amphibians in Classrooms,” Herpetological Review, 2009.
The authors of the article above recommend this pamphlet, produced by Partners in Amphibian and Reptile Conservation (PARC) entitled “Don’t Turn it Loose.”
03/23/11

Spring to Life: From Tadpole to Frog

It’s finally Spring, and in our part of the world, we’re ecstatic. We’ve had a rough winter—we had snow and ice on our city streets every day for about 40 days in a row! The crocuses are blooming in my backyard, and outside the city, frogs are springing to life.

In a way, Spring is a good time to think about our “inner amphibian.” After all, mammals are descended from animals that moved from aquatic environments onto the land over three million years ago. As embryos, our heads in the early stages of development look remarkably similar to shark embryos—with gill arches and all. The metamorphosis of frogs is a process that’s not all that different from what all vertebrates go through, but the difference is that most of the development of birds, reptiles, and mammals—such as the growth of the lungs and limbs—takes place inside an egg or inside the mother instead.*

FROM EGG TO TADPOLE

A female frog first lays eggs underwater, sometimes hundreds of eggs, which form into a jelly-like clump called frogspawn, which floats on the water. Most of these eggs become food for other pond life, but some survive.

Tadpoles developing in eggs. © Dan L. Perlman/EcoLibrary.org

The tiny animal inside the egg grows for about a month, then hatches out of the egg. It looks like a small black fish and breathes underwater with feathery gills on each side of its head.

The tadpole’s tail begins to grow; it wiggles its tail to swim. Tadpoles are also called polliwogs. (The word “polliwog” is from Middle English polwygle. Pol means “head” and wiglen means to “to wiggle”). The tadpole eats algae and other plants that grow underwater.

Tadpole. Photo from Wikipedia.

FROM TADPOLE TO FROGLET

After several weeks, tadpoles begin their metamorphosis. Two tiny bumps appear near the tadpole’s tail—these will grow into back legs.

Two more bumps appear near the frog’s head—these will grow into front legs. Lungs begin to grow inside the tadpole’s body and the feathery gills disappear so that the tadpole will be able to breathe air.

The tadpole now has legs for hopping and walking, lungs for breathing air, but its long tail is awkward on land. Until the tail shrinks and is absorbed into its body, the froglet stays in or near the water.

Froglet with tail. Photo courtesy of www.scienceprojectlab.com

FROGLET TO FROG

When the tail is gone, the frog has completed its metamorphosis. The young frog will now feed on small insects, caught with their long, sticky tongues. It will eventually move away from the pond and find a safe place to grow.

This Spring, take some time to visit a nearby pond or swamp and see this process yourself. And check out the poster below that Susan designed for Earth Day, inspired by a photo by FROGS ARE GREEN photographer friend Joe Furman. All proceeds go to help our amphibian friends.

*I found this idea in Thomas Marent’s lovely and informative book, FROG.

03/9/11

Love Underground: The Shovel-Nosed Chamber Frog

We never stop being amazed by how amphibians are able to survive in the harshest environments. The Shovel-Nosed Chamber frog (Leptodactylus bufonius), for example, lives in the dry subtropical or tropical shrublands or grasslands of Paraguay, Argentina, Bolivia, and Brazil, in areas that have only intermittent freshwater lakes, marshes, and ponds. But this frog has evolved many incredible adaptations for overcoming the challenges of living in these mostly dry conditions.

Going Underground

Unlike most frogs, Shovel-Nosed frogs don’t have ponds or other aquatic areas in which to lay their eggs. They have only the muddy remains of ponds that have dried up. So with their shovel-like noses, they dig a chamber in the mud and then top it with a mud cone. Because no water can penetrate these chambers, the frogs produce a foam nest from the female’s albumin secretions to keep the tadpoles moist. But there is no food in the nest—scientists believe the tadpoles metabolize their own issues for food. Then the frogs wait for a big rainstorm that will wash away the burrow and create a predator-free pond (like a vernal pool) for the tadpoles to grow in. But the story isn’t quite over. After the Shovel-Nosed frogs vacate their burrow, a local toad reuses it as a hiding place.

Take a look at this amazing video of the Shovel-Nosed frog by FROGS ARE GREEN friend Joe Furman. We especially like the frogs’ little mating wiggle!

About the filmmaker:

Joe Furman lives in Houston Texas. He is a lifelong animal photographer and makes wildlife documentaries, mostly about reptiles and amphibians. He is also an artist and cartoonist and father of one.

Like most kids, Joe was attracted to frogs and toads and caught and kept them as pets for awhile, but then would release them back into the wild. He had, and still has, a neverending curiosity about tadpoles and the life cycle of frogs. In his twenties he got the chance to go to Costa Rica to look for the Golden Toads. This event set the course of his life ever since. He has traveled around the world with different organizations to study, film, and photograph reptiles and amphibians, and other wildlife. The kid has never left him. He still love frogs!