Layout 1 (Page 2) - Midpeninsula Regional Open Space District

WILD THINGS
A Celebrated, and Threatened, California Jumping Frog
The California red-legged frog (Rana draytonii) once
ranged from southwest British Columbia to northwest Baja,
California, including portions of the Sierra Nevada mountain
range, where it’s believed to be the title character of Mark
Twain’s famed short story, “The Celebrated Jumping Frog of
Calaveras County.” The California red-legged frog has been
eliminated from more than 70% of its historic range as a
result of a wide variety of human impacts, including urban and
residential development, draining of wetlands, construction
of reservoirs and water diversions, chemical contaminants,
agriculture, overgrazing of livestock, and introduction of
invasive species. These activities can destroy, degrade, and
fragment habitat. Introduced predators and competitors such
as fish, crayfish, and bullfrogs continue to threaten the viability
of many remaining California red-legged frog populations. As
a result, the California red-legged frog was federally listed as
threatened in 1996 and is a California Department of Fish and
Game state species of special concern.
The California red-legged frog is the largest native frog in
the western United States, and is one of two subspecies of the
red-legged frog found on the Pacific coast, the other is the northern
red-legged frog (Rana aurora). California red-legged frogs
range from 1.5 to 5 inches in length. The belly and underside of
hind legs are often red or salmon pink; the back is characterized
by small black flecks and larger dark blotches on a background
California Red-legged
Frog Life Cycle
Adults (Size: 80+ millimeters)
Larger, sexually mature frogs that can
live for up to 8 to 10 years; these
fully-formed frogs are capable
of breeding each year and
often return to the pond
in which they were born
to rear their own young.
Female frogs are
generally larger than
male frogs. Adult frogs
are typically active in the
daytime and will often leap
into water when threatened.
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Subadults (Juveniles)
(Size: 45 – 75 millimeters)
1 to 3 years; almost fully developed;
looks and acts like an adult, but is
not sexually mature. The white upper
lip is a key field mark.
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of brown, gray, olive or reddish-brown. They can also be
recognized by their low, staccato grunts, heard during the few
weeks between late winter and early spring when they breed.
The diet of the California red-legged frog is highly variable.
Insects, occasionally small fish, and frog and salamander
larvae are the most common sources of food, although the
larva/tadpole stage of the frog likely eats algae.
What is needed to support the California red-legged frog life
cycle and the frog’s recovery efforts? California red-legged
frogs inhabit relatively deep, still or slow-moving water in
streams, springs, marshes, ponds, and reservoirs, and require
shallow, warmer aquatic habitat for breeding, but also use
a variety of other habitat types, including damp woods
and meadows.
California red-legged frog recovery efforts include protecting
existing populations by reducing threats, and restoring and
creating habitat. Protective measures include pesticide restrictions,
surveying and monitoring populations, conducting research
on the biology and threats to the species, restoring degraded
habitat, and re-establishing populations of the species within
the amphibian’s historic range. For more information regarding
the recovery efforts, refer to the La Honda Creek Open Space
Preserve Pond Restoration Project article on page 15.
Eggs
Breeding can occur from late November to early April.
Softball sized gelatinous masses contain an average of
2,000 eggs and are deposited at the surface of the
water, often attached to emergent or loose floating
vegetation; eggs hatch in 2 to 4 weeks.
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Illustration by Robert Moncrieff
Larvae (Tadpoles)
(Size: 25 – 40 millimeters)
An aquatic “in-between” phase
from eggs to subadults; larvae
resemble small eels that eventually
develop legs and begin to experience
other physical changes as they metamorphose
(change) into land based frogs. Metamorphosis
usually occurs between July and September
(3 to 7 months after eggs are laid). In this life
stage, they may still have a tail and smaller,
less-developed frog features.
© Gary Nafis, Adult California red-legged
frog and larvae/tadpoles photos.