mountain yellow-legged frog

mountain yellow-legged frog
Name	Mountain yellow-legged frog
Status	Critically Endangered (some species), Endangered (other species)
Status system	IUCN/USFWS
Genus	Rana / Lithobates (historically)
Species	muscosa / sierrae / fisheri (taxonomic splits)

mountain yellow-legged frog

The mountain yellow-legged frog is a group of North American ranid frogs historically placed in the genus Rana and treated in some revisions as Lithobates. These frogs occur in high-elevation waters of the Sierra Nevada, San Gabriel Mountains, Transverse Ranges, and parts of Southern California and Baja California. Populations have declined precipitously since the 20th century, prompting listings under the Endangered Species Act and intense conservation attention from agencies including the United States Fish and Wildlife Service, California Department of Fish and Wildlife, and conservation NGOs such as the Center for Biological Diversity.

Taxonomy and classification

Taxonomic history involves early descriptions by herpetologists who worked with collections in institutions like the Smithsonian Institution and the California Academy of Sciences. Original treatments placed the frogs in the genus Rana; later molecular studies by researchers associated with University of California, Berkeley, University of Washington, and the Museum of Vertebrate Zoology led to proposals splitting populations into distinct taxa (e.g., muscosa, sierrae, fisheri). Debates over generic placement engaged authors publishing in journals such as Herpetologica, Molecular Phylogenetics and Evolution, and Copeia. Nomenclatural decisions have involved the International Commission on Zoological Nomenclature and revisions cited by state listings under the California Endangered Species Act.

Description and identification

Adults historically described by field guides from the National Audubon Society and authors like Stebbins exhibit dorsoventrally flattened bodies adapted to lotic and lentic mountain habitats found by naturalists working in the Sierra Club tradition. Diagnostic characters used by taxonomists and collectors at the Natural History Museum of Los Angeles County include dorsolateral folds, webbing on hind limbs, and yellow patches on the ventral surfaces. Morphological comparisons have been published by researchers affiliated with Stanford University, University of Southern California, and California State University. Life stages—egg masses, tadpoles, juveniles, and adults—are described in field protocols used by the U.S. Geological Survey and the National Park Service.

Distribution and habitat

Historic range maps compiled by the U.S. Fish and Wildlife Service and conservation biologists show distributions across the Sierra Nevada from Yosemite National Park to Sequoia National Park, and in southern ranges including the San Bernardino National Forest and Angeles National Forest. Isolated populations occurred in alpine lakes, montane streams, and glacial cirques documented by park biologists at Kings Canyon National Park and Inyo National Forest. Elevational limits are reported in floristic and faunal surveys coordinated with the National Park Service and the Forest Service.

Ecology and behavior

Ecological studies by researchers at University of California, Davis, University of Colorado Boulder, and University of Arizona report diet items taken from stomach-content analyses in journals like Ecology and Journal of Herpetology. Predation relationships include native predators (e.g., Osprey and Garter snake proper nouns when relevant) and introduced predators documented by the California Fish and Game Commission. Breeding phenology in snowmelt-driven systems has been described in long-term monitoring projects supported by the National Science Foundation and regional inventories by the Sierra Nevada Conservancy.

Threats and conservation status

Primary threats identified in assessments by the IUCN Red List, U.S. Fish and Wildlife Service, and academic reviews include introduced fish such as brook trout and bass introduced through stocking programs administered historically by state hatcheries, chytridiomycosis caused by the fungus Batrachochytrium dendrobatidis documented by microbiologists at Oregon State University and University of Massachusetts Amherst, and habitat alteration from water management projects overseen by the Bureau of Reclamation and the Army Corps of Engineers. Climate change impacts have been modeled in reports by the Intergovernmental Panel on Climate Change and regional climate centers, while wildfire effects have been assessed by researchers at the U.S. Forest Service Rocky Mountain Research Station.

Management and recovery efforts

Recovery planning has been coordinated through multi-agency teams including the U.S. Fish and Wildlife Service, National Park Service, Forest Service, California Department of Fish and Wildlife, and NGOs like the Nature Conservancy. Actions have included nonnative fish removal conducted under permits from the California Department of Fish and Game and herbicide-free eradication trials documented in reports submitted to the U.S. Fish and Wildlife Service Recovery Office. Captive-breeding and reintroduction programs have been established at institutions such as the San Diego Zoo Wildlife Alliance and university facilities affiliated with University of California, Santa Barbara. Legal protections have involved petitions and litigation by groups including the Center for Biological Diversity in federal courts such as the United States District Court for the Eastern District of California.

Research and monitoring methods

Field methods developed with funding from the National Science Foundation and performed by teams from University of California, Santa Cruz, California Polytechnic State University, and the U.S. Geological Survey include visual encounter surveys, mark–recapture using PIT tags referenced in methods guides by the American Society of Ichthyologists and Herpetologists, and genetic analyses using next-generation sequencing conducted in laboratories at the Broad Institute and university core facilities. Disease surveillance protocols for chytrid and ranavirus employ qPCR assays standardized by working groups convened at symposia like the International Congress for Conservation Biology and published in outlets such as Diseases of Aquatic Organisms.

Category:Amphibians of North America