Nevada Fish & Wildlife Office
Pacific Southwest Region

Relict Leopard Frog
(Rana onca)

Class: Amphibia
Order: Anura
Family: Ranidae
Genus: Rana
Species: onca
Length: 1.75 to 3.5 inches
Feed: Adults probably eat insects, whereas tadpoles likely eat plants, detritus, and algae
 

Official Status:

Candidate
 

Life History:

The relict leopard frog, Rana onca, has not been found in Utah since 1950. In fact, the species was believed to be completely extinct until three populations were found in Nevada during the early 1990s. The relict leopard frog formerly occurred in Utah along the Virgin River near St. George in Washington County. Biologists are not sure why this species became extirpated from Utah, but dewatering of the Virgin River, hybridization and competition with introduced frog species, and predation by non-native bullfrogs and fishes are all possible explanations.

Because so few relict leopard frogs have been found, little is known about their feeding and reproductive habits. Adults probably eat insects, whereas tadpoles likely eat plants, detritus, and algae. The species may breed in the spring, but exact times are unknown.
 

Distribution and Habitat:

  Adult frogs inhabit permanent streams, springs, and spring-fed wetlands below approximately 600 m (1,968 ft). Adults may prefer relatively open shorelines where dense vegetation does not dominate. Breeding habitat includes pools or slow moving side areas of streams, with or without emergent vegetation.

The historical distribution of this species is not well documented. The distribution has historically been characterized as springs, streams, and wetlands within the Virgin River drainage from the vicinity of Hurricane, Utah to the Overton Arm of what is now Lake Mead, Nevada, and along the Muddy River in Nevada. The species may have once been present on the Colorado River mainstem. Populations in Utah appear to have been extinct since the 1950s.
 

Threats:

  elimination or dramatic alteration of aquatic habitat due to dams, agriculture, marsh draining, and water development and the spread of predator and nonnative bullfrogs, crayfish, and predaceous fishes and a fungal disease, chytridiomycosis
 

Actions / Current Information:

  Relict leopard frog action plan

 

Conservation Agreement and Rangewide Conservation Assessment and Strategy for the Relict Leopord Frog (Rana Onca) July 2005 (2.4MB PDF)
Last updated: April 16, 2014
July 10, 2012