California Red-legged Frog
Rana draytonii
![[California Red-legged Frog]](/images/7ds.jpg)
Description
Distribution Range
General range map taken from CWHR.
Museum records taken from following institution: CAS Herps.
Thought to currently be extinct in Shasta County. Very few museum records exist. One exists from Redding in 1911, two exist from Manzanita Creek in Lassen National Park in the 1960s but I highly suspect they are mis-identified.
Formerly this species probably ranged in the foothills around the lower Sacramento River valley, possibly including all parts of the valley in Shasta County itself. Maximum altitude is uncertain, but I would be surprised if they made it beyond 2,000 feet this far north in their historic range. Stream habitat I have seen above 1500 feet seems generally unsuitable for the species, but admittedly I have only been to a small portion of stream habitat above 1500 feet.
Typical Elevation
We do not yet have enough records from distinct localities to calculate typical elevation. We need 24 more distinct localities.
Taxonomy
The California Red-legged Frog (Rana draytonii) was originally described in 1852 by Baird and Girard as Rana draytonii. See Amphibian Species of the World.
There are no currently recognized subspecies.
Pronunciation
The assumed IPA pronunciation of this species: ˈ/rɑ nɑ/ /dreɪ ˈtoʊ ni/
Taxonomic Etymology
Rana means “Frog” in Latin, and may have been an interpretation of the vocalized mating call frogs make. The vocalization below is most certainly not intended to be representative of the call this species makes.
draytonii honors Joseph Drayton (Beltz 2006).
Taxonomy Notes
A study of new world representatives of the family Ranidae found five major clades (Hillis and Wilcox 2005 pg. 304). The clade that contains Rana draytonii is known as Amerana (also called the Rana boylii group) and is phylogenetically closer to the European Common Frog (Rana temporaria) than it is to the other four clades in the new world.
This close relation to old world Rana is why this group remains in the genus Rana.
Originally Rana draytonii was described as a distinct species from Rana aurora. Since the original description it was reclassified as a subspecies of Rana aurora (Camp 1917 pg. 115) with an intergrade zone along the coast of Northern California (Stebbins 2003 map 50).
However, the California Red-legged Frog exhibits different habitat preferences, they have vocal sacs and call above water opposed to lacking vocal sacs and calling underwater, and it has different reproductive habitat needs. Those factors have led many to believe they were a truly different taxon for some time.
In 2004, a genetic study (Shaffer, Fellers, Voss, Oliver and Pauly 2004) demonstrated quite clearly that Rana draytonii is a different genetic lineage from Rana aurora. In fact, Rana aurora is actually a closer relative to Rana cascadae than it is to Rana draytonii (Shaffer et al. 2004 pg. 2672). The study found that the contact zone between the two taxa was actually quite small and did not find evidence of hybridization between the two forms within the former alleged intergrade zone, though further nuclear DNA testing was suggested (Shaffer et al. 2004 pg. 2673). They indeed appear to be reproductively isolated as well as morphologically distinct, supporting species level distinction.
Most literature prior to the 2004 study and some current literature still refers to these frogs as Rana aurora draytonii, though that trend appears to be quickly disappearing.
Additional Information
Notes
This species is quite possibly extinct in Shasta County. Historically the California Red-legged Frog was found as far north as the Redding area, but there do not seem to be any recent sightings within Shasta County. A fairly extensive survey in the Cottonwood Creek watershed in 2006 and 2007 did not turn up a single specimen (Fellers 2007).
Cause of Decline
The cause of their decline is probably due to multiple factors. Soon after the gold rush hit California, this species was heavily harvested for food (Jennings and Hayes 1985). Much of this market was in San Francisco and initial harvesting occurred in that area and its surrounding counties. The harvesting appears to have had a bias towards females and is recorded in quantities that is just not sustainable. By the late 1890s harvests were decreasing and moving farther away from San Francisco, indicating depletion of the sources local to San Francisco.
I am unaware of whether or not Shasta County populations were overharvested for the San Francisco market, but there is a distinct possibility they were harvested for local markets during Shasta Counties own gold rush. It would be interesting to work with the Shasta Historical Society to try and determine how much of a frog leg market existed here.
Given that the species is still found in some parts of the San Francisco Bay Area where over harvest is documented, it is unlikely that over harvesting would have been the sole cause of their extirpation here if it was indeed a factor. It is quite possible that another factor was placer mining. Many of the methods used here in Shasta County were extremely ecologically destructive. Stream velocities were increased and entire hill sides were blasted away using high pressure water. The resulting alteration to natural stream velocity and addition of particles could have had a serious impact on the California Red-legged Frog populations here.
The introduction of the American Bullfrog (Lithobates catesbeianus) also may have played a role. Most habitat that is suitable for California Red-legged Frogs is also suitable for American Bullfrogs. They are a larger species and reproduce in much larger quantities, often eating and out competing native species where they have been introduced. I am not sure of when the species was introduced into Shasta County, but it probably happened during the first part of the twentieth century.
The introduction of two invasive crayfish, the Red Swamp Crayfish (Procambarus clarkii) and the Signal Crayfish (Pacifastacus leniusculus) also may have played a significant role. I am not sure when they first appeared here, but these crayfish are voracious predators of frogs, their tadpoles, and egg masses. Every piece of potentially suitable breeding habitat for California Red-legged Frogs that I have investigated here has had one or both of those invasive crayfish species present (as well as American Bullfrogs.)
Even though the last verifiable record for the species in this county I can find is over 100 years ago, I still have hope there is a extant population remaining, perhaps utilizing a cattle stock pond on private property, minding its own business just waiting for a kid who has a field guide, interest in frogs, and access to the land to make the find of a lifetime.
Recovery Plan
The California Red-legged Frog was federally listed as a threatened species in 1996. A detailed recovery plan for the species was published in 2002 (U.S. Fish and Wildlife Service 2002).
The recovery plan calls for re-establishing the species in the Cottonwood Creek drainage where sight records exist as recently as 1987 (U.S. Fish and Wildlife Service 2002 pg 7). If this is successful, we may be able to encourage further natural dispersal of the species back into their historic range in Shasta County by improving and restoring the watershed and controlling detrimental invasive species populations.
One key aspect of the recovery plan is the control of American Bullfrog populations, and that does not seem to be an easy task.
Images
Unless otherwise noted, all images are of wild specimens in Shasta County.
Please be kind, do not hotlink images and do not use images without permission of the copyright owner.
![[California Red-legged Frog]](/images/7sm.jpg)
![[California Red-legged Frog]](/images/60sm.jpg)
©Michael A. Peters
Juvenile. Notice the very prominent dorsolateral fold that distinguishes this species from the American Bullfrog and the Foothill Yellow-legged Frog. Notice the elongated snout compared to the Cascades Frog. Contra Costa County, CA.
![[California Red-legged Frog]](/images/83sm.jpg)
©Michael A. Peters
Underside of sister species, the Northern Red-legged Frog (Rana aurora) demonstrating the color that gives the species it’s name. Kitsap County, WA.
![[California Red-legged Frog]](/images/141sm.jpg)
![[California Red-legged Frog]](/images/142sm.jpg)
![[California Red-legged Frog]](/images/105sm.jpg)
©Michael A. Peters
Juvenile. Young California Red-legged Frogs do not always have the red underside to their groin and legs that give the species it’s name. The red is just beginning to come in on this specimen. Contra Costa County, CA.
![[California Red-legged Frog]](/images/104sm.jpg)
©Michael A. Peters
Yearling. Notice the spots do not have sharply defined edges like they typically do in the Cascades Frog. Contra Costa County, CA.
Habitat Shots
Unless otherwise noted, these habitat shots are from within Shasta County where this species is known to occur.
![[California Red-legged Frog habitat]](/images/163sm.jpg)
©Michael A. Peters
This pond in Contra Costa County is home to a small population of California Red-legged Frogs. It has some vegetation along the sides necessary for cover, has some depth to it necessary for egg laying, and it lacks American Bullfrogs. It is my hope similar ponds exist somewhere up here in Shasta County that also still sustain this species.
Similar Species
Cascades Frog
The Cascades Frog (Rana cascadae) is a montane frog and is found at much higher elevations than the California Red-legged Frog in Shasta County. If the frog was found above 800m (2600 feet) it probably is a Cascades Frog.
The snout of the Cascades Frog is not as elongated as the California Red-legged Frog and the white jaw stripe tends to extend all the way to the shoulder.
Oregon Spotted Frog
The Oregon Spotted Frog (Rana pretiosa), which is probably extinct in Shasta County, occurred in the north east corner of the county well outside the range of the California Red-legged Frog.
Foothill Yellow-legged Frog
The Foothill Yellow-legged Frog (Rana boylii) does share habitat in some places with the California Red-legged Frog but generally prefers small streams with a rocky bottom, and is generally a smaller frog than the California Red-legged Frog. The dorsolateral fold is also far less prominent on the Foothill Yellow-legged Frog.
A big giveaway however is the color of the underside of the rear legs. They are red in the California Red-legged Frog and yellow in the Foothill Yellow-legged Frog. However, since neither species may be touched without a scientific permit, you probably will not be able to view the underside of the rear legs.
Species of Special Concern
This species is listed as a Species of Special Concern by the State of California Department of Fish & Game.
If you come across this species, please note that it may be a violation of state law to collect it or even touch it. Federal laws may also apply.
If you can, please do the following:
- Accurately record the location where the animal was found. The best way to do this is with a GPS device.
- Photograph the specimen. Take as many photographs as you can without causing too much stress to the animal.
- Take note of the habitat and its condition. Photographs are good for this, but do not always tell the entire story.
- Take note on any possible threats to the population. For example, if it is one of our threatened native frog species, is there an American Bullfrog population in the immediate vicinity? Are you aware of an American Bullfrog population in a nearby aquatic system? What about erosion? Introduced trout?
- Report the sighting to the California Natural Diversity Database.
It takes a little effort to file a report, but your report may help the necessary agencies protect that population. It is difficult for them to protect populations they do not know about or populations they think are extirpated. Even species of special concern that are currently doing well in Shasta County should be reported. When population declines happen, they tend to happen very fast. Reports of specific localities where a species is known to have occured may help researchers determine survey sites if our population of one of these species does crash.
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