General Distribution
Historically, the range of the foothill yellow-legged frog extended south to the north and east forks of
the San Gabriel River on the Angeles National Forest. There are several historic locations in the
southern portion of the Los Padres National Forest; these include Piru Creek, Sespe Creek, Hopper
Creek, Santa Paula Canyon, upper Santa Ynez River (at Juncal Campground), upper Indian Creek, and
Santa Cruz Creek (near the Guard Station) (Jennings and Hayes 1994, Stephenson and Calcarone 1999).
However, foothill yellow-legged frogs have not been observed in or south of the southern Los Padres
National Forest ranges since 1978. The last sighting was near Frenchman's Flat along Piru Creek in
1977 (Jennings and Hayes 1994).
Foothill yellow-legged frogs do still occur in several coastal drainages in northern San Luis Obispo
County and Monterey County in and near the northern portion of the Los Padres National Forest. The
species has been recorded in Big Sur River, Willow Creek, Dutra Creek, San Carpoforo Creek, Arroyo
de los Chinos, and Arroyo de la Cruz since 1990 (Stephenson and Calcarone 1999, USDA Forest?Service database). Systematics
The large, widespread genus Rana contains 250 species, 14 of which occur in the western United States.
Foothill yellow-legged frog is part of an evolutionary lineage in North America comprising R. aurora,
R. boylii, R. cascade, R. muscosa, and R. pretiosa (Case 1978). These species appear to be more closely
related to R. temporaria of Europe than to other North American Rana species. Foothill yellow-legged
frog has been recognized as a distinctive species since the work of Zweifel in 1955 (Jennings and Hayes
1994). Habitat Requirements
Foothill yellow-legged frogs occupy rocky streams in valley-foothill hardwood, valley-foothill
hardwood-conifer, valley-foothill riparian, ponderosa pine, mixed conifer, coastal scrub, mixed
chaparral, and wet meadow habitat types (Zeiner and others 1988). They are nearly always found within
a few feet of water. Foothill yellow-legged frogs are frequently found in moving but not swiftly flowing
water (Stebbins 1954). The species is most common along streams with rocky bottoms but has also
been found along streams with mud bottoms (Stebbins 1951). Reproduction
Foothill yellow-legged frogs breed from late March to early May after the high-water stage in streams
has passed and less sediment is being transported. Eggs have been observed in early and mid-May in
streams in southern California, indicating that oviposition occurs later in the south than in the north
(Stebbins 1951). Eggs are deposited in clusters in streams and lakes and are attached to stones,
vegetation, or the bank itself (Stebbins 1954). Tadpoles metamorphose in approximately 3-4 months
(Stebbins 1951, Storer 1925). Adult size is attained in 2 years (Storer 1925), but no data are available on
longevity (Jennings and Hayes 1994). Daily/Seasonal Activity
Foothill yellow-legged frogs are active in the daytime and can be found sunning on the shore or on rocks
in streams. They often dive into water to take refuge under rocks or sediment when disturbed (Stebbins
1954, Storer 1925). The seasonal ecology and behavior of adult foothill yellow-legged frogs is
essentially unknown (Jennings and Hayes 1994). Diet and Foraging
Foothill yellow-legged frogs eat aquatic and terrestrial arthropods, particularly insects. Insects found in
the stomachs of collected individuals include grasshoppers, hornets, carpenter ants, water striders, small
beetles, and dipterans (mosquitoes and others) (Stebbins 1951, Storer 1925). Predator-Prey Relations
Several species of garter snakes, including red-sided garter snake (Thamnophis sirtalis parietalis),
western terrestrial garter snake (Thamnophis elegans), and Oregon garter snake (Thamnophis couchii
hydrophilus), are predators of post-hatching stages of foothill yellow-legged frogs (Jennings and Hayes
1994, Zweifel 1955). Oregon garter snakes have been observed to feed more frequently on tadpoles,
whereas the other two species of garter snakes have been observed to feed more frequently on
metamorphosed individuals (Jennings and Hayes 1994). The rough-skinned newt (Taricha granulosa)
has been recorded preying on foothill yellow-legged frog eggs (Evenden 1948). In addition, when
Centrachid fishes were offered Rana tadpoles and eggs, they ate them readily (Werschkul and
Christensen 1977). Fish, mammals (e.g., raccoons), and birds are likely to prey on one or more stages of
foothill yellow-legged frogs (Zweifel 1955). Literature Cited
Case, S.M. 1978. Biochemical systematics of members of the genus Rana native to western North
America. Systematic Zoology 27(3): 299-311.
Emlen, S.T. 1968. Territoriality in the bullfrog, Rana catesbeiana. Copeia 1968: 240-243.
Evenden, F.G., Jr. 1948. Food habits of Triturus granulosus in western Oregon. Copeia 1948(3): 219-
220.
Jennings, M.R.; Hayes, M.P. 1994. Amphibian and reptile species of special concern in California.
Rancho Cordova, CA: California Department of Fish and Game, Inland Fisheries Division.
Martof, B.S. 1953. Territoriality in the green frog, Rana clamitans. Ecology 34: 165-174.
Moyle, P.B. 1973. Effects of introduced bullfrogs, Rana catesbeiana, on the native frogs of the San
Joaquin Valley, California. Copeia 1973(1): 18-22.
Stebbins, R.C. 1951. Amphibians of western North America. Berkeley, CA: University of California
Press.
Stebbins, R.C. 1954. Amphibians and reptiles of western North America. New York: McGraw-Hill Book
Company, Inc.
Stebbins, R.C. 1985. A field guide to western reptiles and amphibians. 2d ed., revised. Boston, MA:
Houghton Mifflin Company.
Stephenson, J.R.; Calcarone, G.M. 1999. Southern California mountains and foothills assessment:
Habitat and species conservation issues. General Technical Report PSW-GTR-172. Albany, CA: Pacific
Southwest Research Station, Forest Service, U.S. Department of Agriculture.
Storer, T.I. 1925. A synopsis of the amphibia of California. University of California Publications in
Zoology 27: 1-342.
USDA Forest Service. 2002. Reproductive ecology of the foothill yellow-legged frog (Rana boylii) in
Hurdygurdy Creek, Northwestern California: Implications for species conservation and management.
[Homepage of Pacific Southwest Research Station ], [Online]. Available: http://www.fs.fed.us/psw/
topics/wildlife/herp/rabo.html [2000, March 14].
Werschkul, D.F.; Christensen, M.T. 1977. Differential predation by Lepomis macrochirus on the eggs
and tadpoles of Rana. Herpetologica 33: 237-241.
Zeiner, D.C.; Laudenslayer, W.F., Jr.; Mayer, K.E., editors. 1988. California's wildlife. Volume
I: Amphibians and reptiles. Sacramento, CA: California Department of Fish and Game.
Zweifel, R.G. 1955. Ecology, distribution, and systematics of frogs of the Rana boylei group. University
of California Publications in Zoology 54 (4): 207-292.
Information gathered from California DFG - California Interagency Wildlife Task Group
