Walkthrough

SAVING THE MOUNTAIN AND SIERRA NEVADA YELLOW-LEGGED FROGS

The mountain yellow-legged frog was once the most abundant amphibian in Southern California's Sierra Nevada and Transverse Ranges. Just decades ago, it was hard to walk around many of California's alpine lakes without tripping over these diminutive "mountain gnomes."

But today these hardy survivors of freezing, high-elevation winters are vulnerable to a host of modern threats. In fact these frogs are extinct in more than 93 percent of their old mountain homes.

SPECIES BACKGROUND

The mountain yellow-legged frog has two populations that have been declared separate subspecies: a northern and central Sierra Nevada population, and a southern Sierra Nevada and Southern California population. Both populations are adapted to high-elevation habitats without aquatic predators. So unsurprisingly, the main reason for the frogs' decline is the introduction of nonnative trout to alpine lakes. These fish, stocked by the California Department of Fish and Game, prey upon tadpoles and young frogs. The yellow-legged frog has disappeared from the most known historical locations, and most of the largest populations left are near collapse.

Scientists predict the yellow-legged frog could be extinct within decades.

OUR CAMPAIGN

The Center first petitioned to protect the Sierra Nevada population under the Endangered Species Act in 2000. After we won a historic 2011 settlement agreement with the Service (also affecting 756 other species) —the feds proposed protections and more than 2 million acres of critical habitat. After years of federal foot-dragging and a 2016 Center suit, we won a  settlement requiring the Service to determine whether the frog warrants protection.

In response to our legal action, the feds finalized a recovery plan for the endangered Southern California population of mountain yellow-legged frogs in 2019. And thanks to our work, the California Fish and Game Commission has designated all populations of the mountain yellow-legged frog as "candidates" for listing — the first step toward state protection. 

Meanwhile we also defend these frogs from threats like livestock grazing and pesticides.

Check out our press releases to learn more about the Center's actions for mountain yellow-legged frogs.

You've Never Seen A Maine Frog Up Close Like This Before

Do you have an outdoors photo or video to share? Send it to pwarner@bangordailynews.Com and tell us, "I consent to the BDN using my photo/video."

If you're lucky enough to live someplace in Maine where there is water nearby, you have probably heard the sound.

The repetitive chittering sound can be heard echoing from all around you in a virtual symphony of incessant calls.

Today, we're lucky to have an awesome video that shows us which of Maine's common forest creatures is responsible for what some might even consider an annoying racket.

James Treadwell of Cumberland was kind enough to share the video of a gray tree frog, which he encountered not far from his home. He admits it's a sight that many people have not had the opportunity to witness.

"I know people hear them and either they don't really know what they are or they get misidentified as a bird or an insect," said Treadwell, a middle school art teacher for 34 years at MSAD 51, which includes Cumberland and Yarmouth.

"True to their name, they're a tree frog, so they spend a lot of time calling from up in the trees and that's not where people think to look when they're looking for frogs," he said.

Treadwell said the cacophony of spring sound in which this particular tree frog is participating — which the Maine Department of Inland Fisheries and Wildlife refers to as a melodic trill — is simply the amphibian's mating call.

Along with spring peepers, whose appearance and calls are recognized as a sure sign of spring, gray tree frogs are another vocal creature on the landscape. The second part of the video shows a peeper amid its impassioned ritual.

Capturing the video required a base of tree frog knowledge, stealth and a little luck. Treadwell has a keen interest in nature and even has experience in the frog realm.

For six years, he participated as a citizen scientist in a U.S. Geological Survey research project that studied amphibians in Maine and across the country.

"They'd give you an amphibian route that you'd follow, four to five times every spring, and you'd hit 10 locations," Treadwell said.

At each stop, he recorded information such as the time, temperature and weather conditions before listening for frog sounds and then explaining their frequency and intensity.

Treadwell admits because of his interests he was torn during his college days about whether to pursue a career as a science teacher. He settled on art instead, but still enjoys getting out and about as an amateur naturalist.

Treadwell said most people don't get a good look at tree frogs because of their small size and the habitat they occupy. Gray tree frogs are only 1 1/2 to 2 inches in length.

"They're super reclusive and during the day they're extremely well camouflaged," Treadwell said. "You just never see them. You walk right past them all the time, sitting on a tree or shrub, and you never know it."

In fact, when approached, the frogs tend to go silent and wait for intruders to pass by before resuming their song.

In this case, Treadwell crept up on the tree frog slowly and carefully to get into position. He said that because of the number of frogs chorusing, there are many more potential targets.

This specimen was located on a low branch.

"Once I get there, I'll put my headlamp on and they largely ignore you," he said. "They just keep going about their business, as you saw."

Treadwell theorizes that with the frogs' hormones raging and the desire to find a mate strong, they're willing to overlook being in the spotlight.

DIF&W said gray tree frogs are often confused with spring peepers, Maine's only other tree-dwelling frog. However, peepers are only an eighth-inch to 1 1/2 inches long and have a distinctive dark "X" on their back.

Peepers also make a different high-pitched sound, one which does not include the trilling of the brown tree frog.

"They're a little harder to find, because they're miniscule," he said of the peepers.

Our thanks to James Treadwell for sharing his videos and his considerable expertise to help Bangor Daily News readers better understand the unmistakable sounds of Maine's spring tree frogs.

More articles from the BDN

This Frog May Be The First Amphibian Known To Pollinate Flowers

On rainy nights on the verdant coastal plains outside Rio de Janeiro, groups of tree frogs sometimes gather around the pearly white flowers of the milk fruit tree. But while most tree frogs are on the prowl for night-flying insects, one species is after the sugary nectar in the flowers. The tiny, orange Xenohyla truncata's sweet tooth might make it the world's first known pollinating amphibian. And the discovery adds to growing evidence that we need to broaden our understanding of which animals act as pollinators beyond the well-known birds and insects.

During a visit to a spot near the Brazilian town of Armação dos Búzios in December 2020, researchers witnessed a group of the frogs—commonly known as Izecksohn's Brazilian tree frog—feeding on milk fruit. The stomach contents of museum specimens had previously shown that the species is one of the few amphibians in the world to eat fruit, says team member Carlos Henrique de-Oliveira-Nogueira, a biologist at the Federal University of Mato Grosso do Sul in Brazil. The researchers saw one of the frogs wiggle into a flower in search of nectar, then emerge with pollen clinging to the secretions on its moist back. This led them to suggest that the amphibians might play a role in carrying pollen from bloom to bloom, aiding the tree's reproduction. The team's findings recently appeared in Food Webs. "Some species are photographed in flowers, but nobody's ever seen a species interacting with a flower," de-Oliveira-Nogueira says.

The discovery is an encouraging first step, but more research is needed to prove the frogs are pollinators, says Ruth Cozien, a biologist who researches pollination at the University of KwaZulu-Natal in South Africa and was not involved in the new study. Future research could include long-term monitoring of flowers with cameras or the use of frog-barring cages to see if milk flowers are less successful at reproducing when frogs can't access them.

X. Truncata within a Cordia taguahyensis flower. Credit: Henrique Nogueira

There are other questions that still need to be answered as well, de-Oliveira-Nogueira says, such as whether the secretions on the frogs' back harm the pollen or stop it from brushing off on different flowers. The researchers also wonder whether the frogs visit enough flowers to make a difference in the trees' reproduction.

For Cozien, the possible frog-mediated pollination illustrates how unexpected ecological interactions are still out there to be discovered when people do basic fieldwork. The past decade has seen a boom in descriptions of unexpected pollinators, including lizards, opossums, brown rats and cockroaches. Many of those finds came from technology such as camera traps, Cozien says. These devices make it easier to catch secretive species in the act. Lizard pollination in South Africa, for example, has never been directly seen by humans, just in video footage, she says.

The new tree frog observations are also an intriguing glimpse into a species that gets little respect in its homeland, de-Oliveira-Nogueira says. "For most people, it's just one more frog," he adds. In Brazil, frogs that brush up against human habitation, including X. Truncata, often meet unhappy ends, thanks to predatory cats or panicky homeowners.

"It's maybe a game changer because now we have some visibility for these species," de-Oliveira-Nogueira says. "This is a threatened species and maybe the only species [of amphibian] in the world that acts as a pollinator. So if we lose this species, we lose a unique ecological interaction between plants and amphibians."

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