News & Stories

USGS ARMI biologists have been working with agencies, organizations, and institutions across southern California with the goal of enhancing California’s southern Mountain Yellow-legged Frog populations. Conservation efforts began in the late 1990's when populations were discovered to be significantly declining. Soon after, the frogs were listed as endangered under the Endangered Species Act (ESA). ARMI biologists helped develop a captive breeding and headstarting program for the purpose of rearing and raising offspring to release back into the wild. Local zoos, including the Los Angeles Zoo and Botanical Gardens, San Diego Zoo Wildlife Alliance, Santa Ana Zoo, Omaha's Henry Doorly Zoo, and The Aquarium of the Pacific were eager to help.

This past summer, USGS led a multi-partner group that trekked into the San Gabriel Mountains carrying backpacks full of young frogs to release into their native habitat. Please check out the following miniseries for the full coverage of this endeavor.

US Forest Service - Episode 52: For the Frogs - Reintroduction

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The 10th World Congress of Herpetology was held in the city of Kuching, in Sarawak, Malaysia (northwest Borneo) August 5 – 9. ARMI scientists Brian Halstead, Blake Hossack, Pat Kleeman, and Erin Muths presented research papers. There were over 1400 delegates at the Congress, with > 900 contributed talks and 33 symposia.

Halstead and Muths organized a symposium targeted at graduate students (What Editors Want: A Guide to the Publication Process for Graduate Students) that included talks from 7 past and present editors, including Judit Voros, co-editor of Amphibia-Reptilia and Secretary General of the World Congress.

Hossack presented a talk co-authored by ARMI scientists Kelly Smalling and Brian Tornabene titled: “Energy-related secondary salinization of wetlands: Coordinated experiments and field surveys to identify mechanistic links with amphibian abundance”. This invited talk was included in the symposium titled: Haunting the seaside: Integrative biology of salt tolerance in amphibians.

Halstead presented a talk titled: “Effects of translocation and head-starting on giant gartersnake (Thamnophis gigas) behavior and survival”, co-authored by USGS scientist A. M. Nguyen and B. D. Todd (University of California, Davis). This invited talk was included in the symposium titled: Improving conservation and mitigation outcomes of snake translocations—global lessons.

Kleeman presented a contributed talk co-authored by Halstead and J.P. Rose (ARMI scientists), and collaborators from the Nevada Department of Wildlife, K. Guadalupe and M. West, titled: Initial demographic estimates for two species of narrowly endemic toads in central Nevada: Anaxyrus monfontanus and Anaxyrus nevadensis.

Muths’ presentation, co-authored by L. Bailey, A. Fueka, L. Roberts (Colorado State University) and B. Hardy (Chapman College), was in the symposium titled: Improving animal welfare. This invited talk was titled, “Methods in marking toads: PIT tagging versus photography”.

The World Congress is held every four years on different continents with the specific aim of facilitating attendance from herpetologists around the world especially those from developing countries. The first World Congress was held in Canterbury, Great Britain in 1989, with subsequent congresses in locations including China, Brazil, Australia, and Canada. ARMI hosted a symposium on amphibian decline in 2012 at the 7th World Congress in Vancouver.

Congress delegates in Kuching enjoyed multiple plenary talks with topics ranging from Bornean flora and fauna, to the Biogeography and Evolution of reptiles in the Arabian Peninsula, to Frog diversification in Old World tree frogs.

USGS ARMI scientists recently published a critical review on what is known about the effects of harmful algal blooms (HABs) on amphibians and reptiles.

HABs are a persistent and increasing problem globally in both freshwater and marine environments, yet we still have limited knowledge about how they affect wildlife. HABs can occur when colonies of algae have abundant resources, grow rapidly, and produce cyanotoxins. This natural phenomenon was first described in the late 1800s but have become more common due to increases in nutrient inputs and availability (e.g., from agriculture or runoff) and global temperatures that favor their growth.

Although semi-aquatic and aquatic amphibians and reptiles have experienced large declines and occupy environments where HABs are increasingly problematic, their vulnerability to HABs remains unclear. The current review was designed to synthesize existing information of the effects of cyanotoxins on amphibians and freshwater reptiles. The information gained by evaluating and synthesizing previous studies and reported mortality events could enhance monitoring and conservation efforts while also guiding future studies on both amphibians and reptiles.

Our review highlights how cyanotoxins can be lethal and negatively affect larval amphibians, but information on effects on reptiles or embryonic and adult amphibians is lacking, apart from a few observational studies. Cyanotoxins can have systemic effects and negatively influence reproductive, digestive, and liver function in amphibians. Given that amphibian and some reptile populations are declining worldwide, it is important to increase monitoring and experimental efforts to understand the singular and synergistic effects of these toxins. It will also be important to better understand the events that cause algal blooms to synthesize and release toxins and effects of HABs that do not produce cyanotoxins. We also propose future near-term and long-term studies that could help clarify the population-level effects of HABs on amphibians and reptiles and could enhance monitoring and management efforts, especially in areas where HABs have been documented consistently.

California red-legged frog recovery partners have collectively moved the species closer to recovery, most notably through their efforts to reestablish the frog in the southern-most portion of its range where it had disappeared decades earlier. Over the years, these individuals have demonstrated extraordinary vision, leadership, and collaboration in developing a bi-national plan for reintroducing the species, which includes transporting egg masses from Baja California, Mexico, to sites in Riverside and San Diego counties, California. Efforts to work with landowners to identify suitable habitat for releases, along with management and monitoring of the species, exemplify the Service’s mission of working with others to conserve species and their habitats for the benefit of the American people.

Fish & Wildlife Service has recognized ARMI biologists Robert Fisher, Adam Backlin, and Elizabeth Gallegos as crucial partners for the success of this project.

A new paper by Kissel et al shows how complex life cycles interacting with climate change can lead to counter-intuitive outcomes for amphibian populations: https://doi.org/10.1016/j.ecochg.2023.100081

The first widescale assessment of methylmercury in adult amphibians in the U.S. shows that this toxic compound is common, widespread and, at least for some populations, can reach very high levels. The ARMI-led publication brought together scientists from around the country to test more than 3,200 amphibians representing 14 species from 26 populations. Amphibians are the most endangered group of vertebrates worldwide, but prior to this study, little information was available on mercury bioaccumulation in amphibians across the U.S.

Mercury is a contaminant of global concern that can harm humans and wildlife. In aquatic ecosystems, microbes can convert elemental mercury to methylmercury, which increases risks because methylmercury is more bioavailable, more toxic, and it biomagnifies through food webs.

Study results showed that the amount of methylmercury in amphibians varied widely among sites and by life history characteristics, such as diet, size, and sex. Amphibian methylmercury concentrations ranged from barely detectible at some locations, to levels above wildlife health benchmarks in others. The study also evaluated using dragonfly larvae to estimate bioaccumulation for amphibians that can’t be sampled because they are rare or secretive. Scientists determined that the concentration found in these insects can provide insight into methylmercury bioaccumulation in amphibians.

Despite its toxicity, scientists only have a limited understanding of methylmercury’s effects on amphibians and these results can be used to inform future research on the health effects of methylmercury exposure on amphibians. The study also provides new methods and baseline data that can help scientists and managers assess the risk from mercury for species of management concern, including species listed as threatened and endangered under the Endangered Species Act.

To view the full article click this link: https://pubs.acs.org/doi/10.1021/acs.est.3c05549

As first appeared in USGS NTK:

My late fall trek to Lost Lake in Rocky Mountain National Park to look for evidence of toad breeding is beautiful. The aspen leaves are golden. The air is downright cold at the 7 am start. The ten-mile hike starts downhill but soon angles up and continues up for the next eight miles. That is a lot of time to think about the end of another summer field season and about how few toads we observed. I can’t help but wonder if our field techs somehow overlooked breeding and egg masses? Or was it because it didn’t happen? It was only early October, but I settled in to a decidedly grim and early Halloween-edgy mood that was resistant to the bright blue of the sky and clung to me like a veil the rest of the hike.

Not a soul was camping at Lost Lake. The lake was still with only a few ravens providing their opinions on campers and, no doubt, toad conservation. All senses narrowed to look for a toadlet or an adult toad as I poked through the drying grasses and shrubs around the lake, and hopefully scanned the water’s edge. I could feel, more than see, the daylight dwindling.

On the far side of the lake I saw her, sitting on the shoreline. I stopped short as I saw the stiffness of her body and the blank white stare of her eye. The toad was dead. But hadn’t been dead long. I pulled out the “tools of the trade” and measured her, checked her for an identifying passive integrated transponder tag, and swabbed her to test for the amphibian chytrid fungus. She was not marked, and I only assumed she was a female based on size. I recorded a few bits of environmental data, and although firm-ish, the toad was in no condition to travel for further examination. I felt a chill and realized that the sun was completely gone. I left her on the shore with a quick prayer to the amphibian goddess and a furtive look around for moose.

Boreal toads, like the one I found, have been on the decline in Rocky Mountain National Park (RMNP), and the southern Rocky Mountain region for a while. One contributor to these declines is the amphibian chytrid fungus that thickens the skin, blocks osmosis (water intake), and eventually leads to heart attack and death. As a research zoologist, my colleagues and I have been working on amphibians in RMNP in northern Colorado for three decades. Our work ranges from questions of immediate interest to the National Park Service, like “how are the wood frogs doing with the hydrological changes on the west side of the park,” or “why are boreal toads declining” to overall management questions like, “what is the status of the amphibian species in the park and what factors may affect persistence?”

Although there are some bad days like my autumn hike to Lost Lake, there are glimmers of hope, or at least of gains in information that we might use towards amphibian conservation. We are currently working on a paper using three decades of data on chorus frogs, salamanders, and wood frogs in RMNP to examine changes in persistence over time across the landscape of the park. This work also considers a variety of mechanisms (e.g., visitor use) that may affect the probability of persistence and thus provides RMNP with information that can contribute to conservation decisions about the management of the park’s amphibians.

Erin Muths is a research zoologist at the Fort Collins Science Center and is a principle investigator for the Amphibian Research and Monitoring Initiative for the Ecosystems Mission Area. Her lab has studied boreal toads and other amphibians in the Rocky Mountains for more than 25 years. She is going to be sorcerer for Halloween.

As first appeared in USGS NTK:

First of all, newts are not the villains, instead, they are often the victims.

Newts are at risk, along with many animals, from climate change and from disease. In fact, they could be poster animals for climate change: In southern California, recent record warm air temperatures along with peak drought conditions are linked with a 20% reduction in mean body condition (e.g., mass) in the California newt (Taricha torosa)*. The disease Batrachochytrium salamadrivorans (Bsal, literally eater of salamanders in Latin) has caused significant devastation to salamander populations in Europe. This fungal disease affects primarily newts and salamanders and the Northeastern U.S. is considered the salamander capital of the world. While Bsal is not present in the United States now**, there is serious potential for the disease to spread from Europe to the U.S. through the pet trade***.

Second, newts are quiet neighbors that contribute to society.

For example, newts eat a variety of insects, and they are eaten by birds, snakes, and some mammals.

Third, newts appreciate Halloween and keep it alive all year!

Newts have three distinct developmental life stages that are in effect, costume changes! They begin as aquatic larva, metamorphose into terrestrial juveniles (sometimes called efts), then metamorphose into adults.

And finally, newts value their eyes.

If you are really looking for some eye of newt, go look in your local grocery, “eye of newt” is actually a very un-scary and easily acquired mustard seed.

Erin Muths is a research zoologist at the Fort Collins Science Center and is a principle investigator for the Amphibian Research and Monitoring Initiative for the Ecosystems Mission Area. Her lab has studied boreal toads and other amphibians in the Rocky Mountains for more than 25 years. She is going to be sorcerer for Halloween.

Michael Adams is a supervisory research ecologist at the Forest and Rangeland Ecosystem Science Center and is the Lead for the Amphibian Research and Monitoring Initiative for the Ecosystems Mission Area. His lab has studied newts and other amphibians in the Pacific Northwest for the past 25 years. His Halloween plans are a mystery to everyone including himself.

References:

*Bucciarelli, G.M., Clark, M.A., Delaney, K.S. et al. Amphibian responses in the aftermath of extreme climate events. Sci Rep 10, 3409 (2020). https://doi.org/10.1038/s41598-020-60122-2

**Waddle, J.H., Grear, D.A., Mosher, B.A., Grant, E.H.C., Adams, M.J., Backlin, A.R., Barichivich, W.J., Brand, A.B., Bucciarelli, G.M., Calhoun, D.L. and Chestnut, T., 2020. Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians. Scientific reports 10(1), p.13012.

***Connelly, P.J., Ross, N., Stringham, O.C. and Eskew, E.A., 2023. United States amphibian imports pose a disease risk to salamanders despite Lacey Act regulations. Communications Earth & Environment, 4(1), p.351.

Recent ARMI-led research showed the removal of invasive American bullfrogs from livestock ponds and small lakes in southern Arizona also resulted in the apparent local extirpation of two pathogens associated with the bullfrogs. The American bullfrog is native eastern North America but has become widespread in the West, where it preys on many native species of conservation concern. Other recent ARMI-led research from the area suggested that American Bullfrogs could act as reservoirs for pathogens like amphibian chytrid fungus (Batrachochytrium dendrobatidis; Bd) and ranaviruses, which are often lethal to native amphibians, but less so to American Bullfrogs.

In the early 2000s, American bullfrogs were eradicated from ponds in the Buenos Aires National Wildlife Refuge near the Arizona-Mexico border to assist with the reintroduction efforts for the federally threatened Chiricahua Leopard Frog. In 2015, the bullfrog reinvaded the refuge and was once again removed. This reinvasion from outside the refuge motivated funding for a multi-year, landscape-scale eradication program. In the fall-winter of 2016 and the winter of 2020-2021, the research team tested the water at bullfrog eradication and control (no eradication efforts occurred) sites for the DNA (environmental DNA or eDNA) of invasive bullfrogs, federally threatened Chiricahua Leopard Frogs, and Bd and ranaviruses.

Results from the eDNA sampling showed American Bullfrogs were eradicated successfully from most sites, and where bullfrogs were eradicated, the pathogens were also no longer detected. Chiricahua Leopard Frogs did not increase in occurrence after eradicating bullfrogs, possibly due to an exceptional drought that could have limited the ability of native amphibians to colonize sites.

To our knowledge, this is one of the few studies to link eradication of an invasive species to co-eradication of emerging pathogens. Our spatially replicated experimental approach provides strong evidence that management of invasive species can simultaneously reduce predation and disease risk for imperiled species.

To view the full article click this link: https://doi.org/10.1111/conl.12970

Introduction: Designs for safe and effective road crossing structures for small animals are typically under-road microtunnels and culverts which have varying levels of effectiveness reported in the scientific literature. Many species, particularly migratory amphibians, may have limited ability to find and use passages if they are too far apart, resulting in substantial barrier effects.

Methods: We designed a novel open elevated passage (elevated road segment: ERS), similar to a low terrestrial bridge, that could theoretically be built to any length based upon species needs and movement characteristics. A 30 m length prototype ERS was installed along a forest road with a history of amphibian road mortality in Sierra National Forest, Fresno County, CA, USA. From 2018 to 2021, we monitored small animal activity under the ERS in relation to surrounding roadside and forest habitats using active infrared cameras.

Results: We documented a total of 8,815 unique use events, using species specific independence criteria, across 22 species of amphibians (3), reptiles (4), and small mammals (15). Poisson regression modeling of taxonomic group activity under the ERS, roadside and forest, showed that amphibian activity was highest in the forest habitat, no differences were observed for reptiles, and small mammal activity was highest under the ERS. However, mean activity estimates under the ERS were equal to or greater than the open roadside habitat for all 22 species, suggesting that adding cover objects, such as downed logs and vegetation may further enhance passage use.

Discussion: Overall, results showed that the design of the ERS crossing has potential to provide high connectivity for a wide range of amphibian, reptile, and small mammal species while reducing road mortality. ERS systems can also be used in areas with challenging terrain and other hydrological and environmental constraints. Incorporating current road ecology science, we provide supplemental ERS concept designs for secondary roads, primary roads and highways to help increase the options available for road mitigation planning for small animals.

To view the full article click this link: https://doi.org/10.3389/fevo.2023.1145322

This is one of many research studies USGS is conducting to inform safe and effective road crossing systems for amphibians and reptiles. See https://www.usgs.gov/centers/werc/science/reptile-and-amphibian-road-ecology for more information.