True Frogs: Ranidae

The bullfrog (Rana catesbeiana), one tough and adaptable frog, exemplifies the Ranidae.

Most accounts list it as an indigenous species east of the Rocky Mountains, with a late nineteenth and early twentieth century introduction in the West, in conjunction with an American taste for frog legs cuisine.

Able to outlast the dietary craze, Bullfrogs multiplied in western ponds, lakes and wetlands, until they became the dominant amphibian in their territory.

Size and dietary habits explain their adaptive success. North America's largest frog species consume almost anything that moves in their territory such as fish, insects, other frog species, and other bullfrogs.

Scientists express concern that the bullfrog's territorial dominance contributes to declining populations of other frog species such as the two native Red-legged frog species.

• California Red-legged frog (Rana draytonii)

• Northern Red-legged Frog (Rana aurora)

Once abundant throughout the state, the California Red-legged frog population has decreased over 90% and has been listed on the Endangered Species list since 1996.

The remaining population now survives primarily along California's coastal areas, where they still compete for territory with California's coastal loving human population.

According to the Center for Biological Diversity, in 2010, "the U.S. Fish and Wildlife Service today designated more than 1.6 million acres of critical habitat for the California red-legged frog in 28 California counties. The designation is three-and-a-half times as large as the Service's 2006 designation, which the agency acknowledged was flawed because of political interference by the Bush administration."

Northern Red-legged frogs (Rana aurora) inhabit coastal and inland areas of the Pacific Northwest from northern California to British Columbia.

They prefer slow moving or still, shallow water habitats for breeding. During non-breeding season their range extends to many of the nearby forest floors.

The name red-legged frog comes from the red color of the back of the legs and bodies.

While they are not listed as endangered, their populations have declined over the years due to habitat destruction and habitat competition with the larger and more aggressive Bullfrog.

Large green frogs with spots and dorsal ridges along the sides of the body generally get categorized by the name Leopard Frogs.

Leopard frogs inhabit many water habitats across North America and Central America, accounting for their nicknames such as meadow frog and grass frog.

Once believed to be a single species, scientific research, especially DNA analysis, now suggests the existence of anywhere from twenty to thirty different leopard frog species.

In areas where species overlap, hybridization can also occur.

The Northern Leopard Frog (Rana pipiens), probably the most widespread of the species, inhabits areas across most of the northern United States and southern Canada.

Rana pipiens also now serves as the benchmark for organizing scientific thinking on all leopard frogs, which now get grouped into what is called the Rana pipiens complex.

Amphibian populations across the United States continue to decline. Currently the United States Fish and Wildlife Service lists the actions it has taken with respect to various leopard frog populations, and their potential for endangered listings as follows:

• Relict leopard Frog (Lithobates onca): Candidate. A species under consideration for official listing for which there is sufficient information to support listing.
• Chiricahua leopard frog (Rana chiricahuensis): Threatened. A species "likely to become endangered within the foreseeable future throughout all or a significant portion of its range."
• Vegas Valley leopard frog (Rana fisheri): Resolved Taxon. Species that have been petitioned for listing and for which a Not Warranted 12 month finding or Not Substantial 90-day finding has been published in the Federal Register. Also includes species that have been removed from the candidate list.
• Ramsey Canyon leopard frog (Rana subaquavocalis): Resolved Taxon
• Northern Leopard Frog (Rana pipiens): Under Review. Species that have been petitioned for listing and for which a 90 day finding has not been published or for which a 90 day substantial has been published but a 12 Month finding have not yet been published in the Federal Register.
• Lowland leopard frog or San Felipe leopard frog (Rana yavapaiensis): Species of Concern. Species that have not been petitioned or been given E, T, or C status but have been identified as important to monitor.

Picture three shows the Rio Grande Leopard Frog.

© 2005-2012 Patricia A. Michaels