“What do frogs do in winter?” That is a question we hear frequently. Meters-thick ice covers high elevation Sierra Nevada lakes for about nine months of the year. For an animal that spends summer days lounging on rocks in the sun, winter imposes a radical shift in lifestyle. But historically, we could not document frog winter behavior through direct observation. Although scuba diving allows observation of some taxa, winter ice, elevation, and remoteness prevent us from diving in Sierra lakes.
Enter David Lang and his team, who developed the Trident underwater drone at OpenROV and Sofar Ocean Technologies. Over the past few years, our team used a Trident to search for frogs in a frozen lake. This technology allowed us to find frogs and tadpoles, and to capture video to document their overwintering behavior. David and some of his colleagues joined us at our study lake on two late winter expeditions and experienced our “eureka” moments in which we saw frogs and tadpoles as never before. Through the lens of the Trident and the VR goggles, we finally saw the frog’s eye view of life under the ice.
In his recent OneZero article, David describes how the Trident makes this project possible. More generally, he explores the potential for tech to enhance conservation projects. We are happy to see David’s story published, and honored that he focused on our project. Read his story here.
We recently sent out our annual Mountain Lakes Research Group newsletter in which we summarize the highlights from our our research and conservation-related activities in 2018. We also discuss the funding challenges that we face, exacerbated by the prolonged shutdown of the federal government, and our fundraising plans for the future. If you would like to receive future newsletters, please let us know.
The Conversation recently published a story about how scientists move butterflies, sea turtles, and frogs as part of conservation-related activities. The section on frogs features mountain yellow-legged frogs and was written by Mountain Lakes Research Group team member, Roland Knapp. Have a look.
The latest release in the Yosemite Nature Notes video series features the Sierra Nevada yellow-legged frog and describes ongoing efforts to recover this species in Yosemite National Park. Check it out.
A paper entitled “Disease and climate effects on individuals drive post-reintroduction population dynamics of an endangered amphibian” by Max and Roland was published in Ecosphere today. The accompanying UCSB story is available here. Although developed for mountain yellow-legged frogs, the hierarchical Bayesian hidden Markov model they developed might be applicable to other species impacted by the amphibian chytrid fungus.
In this new video, UCSB videographer Spencer Bruttig talks to Roland during a visit to one of his Yosemite study sites and gets the latest on the outcome of frog conservation efforts there. Amazingly, despite all of the challenges the Sierra Nevada yellow-legged frog has faced during the past century, the frogs are making a remarkable comeback. Hear about this exciting turn of events from someone who witnessed the frogs’ decline and now the beginning of their recovery.
“Ranaviruses infect mountain yellow-legged frogs (Rana muscosa and Rana sierrae) threatened by Batrachochytrium dendrobatidis” by Tom, Roland, and Angela Picco (United States Fish and Wildlife Service) appears in Herpetological Conservation and Biology. The paper (available here) documents the presence of a ranavirus in a small number of mountain yellow-legged frog populations. Despite causing occasional tadpole mortality events, ranaviruses play a small role in large scale mountain yellow-legged frog declines, especially when compared to the fungal pathogen Batrachochytrium dendrobatidis.
In the Sierra Nevada, the winter of 2015-2016 was one of the driest on record. During the following summer, a habitat in Yosemite National Park containing Sierra Nevada yellow-legged frogs slowly dried up. Just before the last pools dried, Yosemite mounted a rescue of the tadpoles stranded in the shrinking pools. Several thousand tadpoles were collected and flown via helicopter to a lake upstream in the watershed. This video shows the rescue in action.
A paper by Roland and colleagues was published today in the Proceedings of the National Academy of Sciences, USA. The accompanying UCSB story is available here. The study shows that despite the ongoing presence of introduced fish and the amphibian chytrid fungus, Sierra Nevada yellow-legged frogs are recovering across Yosemite National Park. This recovery is occurring because some lakes have been restored to their original fishless condition, and frogs are developing increased resistance to fungal infection. These results suggest that some amphibians may be more resilient than is often assumed, and with appropriate management, declines of such species may be reversible. That is great news!
Read the new paper here. Published today in the journal Ecosphere, Tom, Roland, and Cherie Briggs (UC Santa Barbara) describe some of the ways in which mountain yellow-legged frog declines impact alpine lake communities. Contrary to expectations, the large scale loss of these frogs is not associated with secondary extinctions or changes in structure and composition of the benthic macroinvertebrate community, which contains most of the prey and competitor species for frogs and tadpoles. Notably, these results differ from 1) the consequences of frog declines in other ecosystems, and 2) the consequences of fish introductions in the Sierra. Although impacts of frog declines on the taxa examined in this study were small, mountain yellow-legged frog declines are associated with secondary declines in other species, like gartersnakes.