Carnegie Museum of Natural History

One of the Four Carnegie Museums of Pittsburgh

frogs

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Frosty Frogs and Tunneling Toads

by Melissa Cagan and Hannah Smith

In the fall, many animals begin to prepare for winter. Squirrels collect food, groundhogs eat extra food to store as fat, birds migrate to warmer regions…but what do frogs do?  Although frogs and toads don’t seem to make any special preparations for the approaching cold, they survive extraordinarily cold temperatures every winter.  How do they manage this?

An American toad hops through fallen leaves.

A Long Winter “Nap”

Like other amphibians, frogs and toads are cold-blooded.  This means their body temperatures change to match the temperatures of their environment.  When winter comes around, frogs and toads go into a state of hibernation.  They find a place to “sleep” through winter and slow their metabolism, heart rate, and breathing rate to conserve energy.  Frogs and toads rely on two different hibernation strategies depending on whether they spend more time on land or underwater.

Above are models of three different sized frogs. The largest model is a leopard frog, the medium model is a grey tree frog, and the smallest model is a spring peeper.

Beneath the Icy Ground

Aquatic species, such as the green frog and the bullfrog, rest on pond or river bottoms.  So long as the water doesn’t completely freeze, frogs or underwater toads will be able to survive the winter…by breathing through their skin! If these animals buried themselves in mud, they would not be able to absorb enough oxygen.  Species that spend more time on land however, such as the American toad or the spring peeper, find drier places to sleep the winter away. Since the ground surface can freeze when temperatures drop dramatically, land frogs and toads need to find places that protect them from snow or frost.  This may require a frog or toad to dig deeply enough into the ground that they reach below the frost line – around 50 cm. or more than 20 in. deep!

Frogging Awesome!

Frogs and toads are much tougher animals than you might imagine.  Next time you see a frog or a toad, give them a tip of your hat – they are exceptionally hardy (resilient) creatures!

frog on a fallen leaf

Frozen Frogs

A few, unique species of frogs have found a different way of dealing with cold temperatures.  These frogs, like the wood frog and some tree frogs, actually freeze part of their body! These special creatures are able to freeze around 40% of their body’s water content.  In this state, the frogs don’t breathe, have no heartbeat, and stop all blood flow.  Once spring comes, the frog thaws its body and comes back to life!

Can You Find the Frogs?

Frogs are great at hiding amongst their environment. They often hide in reeds, plants, and on the banks of ponds or other bodies of water.  There are frogs hiding in each of these photos…how many can you find?

marshy area with frogs
wetlands with frog hiding
wetland marsh with frogs

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Carnegie Museum of Natural History Blog Citation Information

Blog author: Cagan, Melissa; Smith, Hannah
Publication date: March 20, 2019

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Scientists Live – Jennifer Sheridan

Assistant Curator of Amphibians and Reptiles, Jennifer Sheridan, discussed her upcoming research and teaching trip to Borneo on Facebook Live! If you missed it live, check out the recording to learn all about her trip. While in Borneo, she will search for frogs to study how they are affected by climate change and the actions of humans. Learn about why the trip is important and how you can follow along while she is traveling.

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Fossil Search: Expert Assistance

paleontologists using GPS
During a search for the contact point of two different Sheep Pass Formation rock units, Amy Henrici uses GPS-linked topographic maps in her iPad to locate the zone referenced in a stratigraphic map held by Richard Hilton.

by Patrick McShea

The frog fossil expedition workforce doubled briefly with the arrival of a two-person team affiliated with Sierra College in Rocklin, California. Earth Science professor Richard Hilton and field assistant Tina Campbell drove east from the Sacramento area, crossing the Sierra Nevada and a large portion of the Great Basin to meet us for two days of field work. They then proceeded to another fossil locality in the region to retrieve material discovered during earlier summer field work.

The Sheep Pass Formation within the South Egan Wilderness was familiar territory for both. In 2012 and 2013 they participated in larger expeditions to the area that involved not just Carnegie Museum of Natural History and Sierra College, but also the University of Nevada at Las Vegas.

Because Hilton is chairmen of Sierra College’s natural history museum,  our fireside conversations included the potential for using blog posts to broaden the audience for information about paleontological field work. Through the combination of his generosity, two-burner stove, and culinary skills, camp meals also improved.

paleontologists eating at campsite
Dinner at dusk, including Caesar salad, baked beans, and hamburgers.

Patrick McShea is a museum educator who is traveling through Nevada with Vertebrate Paleontology Collections Manager Amy Henrici to search for frog fossils. He frequently blogs about his experiences.

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Shifting Formations

Nevada’s White River Valley from high ground in the South Egan Wilderness.

by Patrick McShea

From Elko, Nevada, the Carnegie Museum of Natural History frog fossil expedition shifted some 125 miles southeast to steep winding canyons within the South Egan Wilderness, a mountainous tract of more than 67,000 acres.

The move involved a change in the age of the rock outcrops we searched. Near Elko our efforts were confined to various associated rock layers, which geologists categorize as the Elko Formation, a thick and wide spread unit which formed some 46 – 39 million years ago during the Eocene Epoch. In the South Egan Wilderness, we explored the Sheep Pass Formation, a sequence of far older rocks which formed during the Late Cretaceous through middle Eocene Epochs some 70-46 million years ago.

Daily procedures were far different in the BLM-managed wilderness than on the outskirts of Nevada’s 15th largest city.

Instead of commuting to outcrops from a motel in Elko’s center, we hiked to rock exposures more than a mile from our simple camp site, proceeding up dry stream beds and ascending eight staircase-like water falls to reach the fossil-bearing units at elevations exceeding 6,700 feet. Evenings were cold, star-filled, and absolutely quiet but for the occasional howls and yips of coyotes.

Because a 2012 wildfire burned over 10,000 acres of sage brush, juniper, and pinyon pine, our camp area was a surreal landscape of charred trees.

 

Patrick McShea is a museum educator who is traveling through Nevada with Vertebrate Paleontology Collections Manager Amy Henrici to search for frog fossils. He frequently blogs about his experiences.

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Planning for Field Work

Backpack, book, and hammer sitting in the desert

by Patrick McShea

Planning for field work resembles vacation travel preparation in a fundamental way. Much consideration is given to gathering all necessary gear, and the mere assembly of these items triggers a kind of mental departure that precedes the physical one.

As a former English major, I’ve learned to manage this sometimes disorienting state by reading or re-reading destination-related articles, essays, and books.

For the Elko, Nevada sites where Amy Henrici and I hope to collect frog fossils this fall, John McPhee’s “Basin and Range” (Farrah Straus Giroux, New York, 1980) has particular relevance.

The book recounts the author’s travels along Nevada’s Interstate 80 corridor in the company of renowned Princeton University geologist. McPhee successfully translates into layperson language the region’s “geology in its four-dimension recapitulations of space and time.”

Fossils, as signs of ancient life, add critical evidence to such recapitulations. Near Elko, far up in the high desert hills south of Interstate 80, we’ll search for frog fossils to further our understanding of Earth’s past.

Desert near Elko, Nevada

Patrick McShea is a museum educator who is traveling through Nevada with Vertebrate Paleontology Collections Manager Amy Henrici to search for frog fossils. He frequently blogs about his experiences. 

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Where to Look for Fossils

Amy Henrici
Vertebrate Paleontology Collections Manager Amy Henrici in the field.

As I travelled west from Pittsburgh to meet Carnegie Museum of Natural Hisotry Vertebrate Fossil Collection Manager Amy Henrici for a frog fossil hunting expedition in eastern Nevada, the same question was asked by each of my airplane seat mates.

“How do you know where to look for fossils?“

For the sites we planned to visit the answer was simple. Earlier written reports by geologists mapping rock formations and mineral deposits noted the occasion occurrence of fossils in certain rock layers.

Fossil searches involved locating and visiting sites where such rock layers are exposed on the surface, and then examining fragments that have eroded from these outcrops.The full process, which might stretch over decades, is an example of how published findings allow one branch of science to serve another.

As a geologist friend takes great pleasure in explaining, “Geologists let paleontologists know where fossils are in the multitude rock layers of Earth’s history, in time and in place.”

Patrick McShea is a museum educator who is traveling through Nevada with Vertebrate Paleontology Collections Manager Amy Henrici to search for frog fossils. He frequently blogs about his experiences.