Frogs and Toads of Humboldt County, California - by Ellin Beltz
IntroductionHumboldt County frogs and toads are members of four Families of Anurans. They range from the rare and primitive tailed frogs to one of the greatest frog success stories on earth, the Pacific treefrog.
They share their need for clean water and food with all other inhabitants of our planet, and decline rapidly where pesticides and herbicides are deliberately sprayed as well as where accidents or lack of thought introduce those and other petrochemical derivatives into the waterways.
Toads were once so common in American cities that the U.S. Department of Agriculture wrote a book about their vital role in eating mosquitos in 1908. Then DDT was discovered, the mosquitos died and the toads died too. Toads are highly unlikely in any American city now - less than 100 years after the book was written.
Frogs have thinner skin than toads, are not toxic and in general make a better meal so they have learned to move faster and be more skittish than toads. Both, unfortunately are - as the rest of us - subject to viral, bacterial and fungal infections. All three have broken from their native reservoirs and are now infecting amphibians worldwide. In addition, parasitic nematodes have been linked to frog deformities and the ever-increasing ultraviolet reaching earth's surface destroys or deforms amphibian eggs and larvae.
It's a tough and changing world for these ancient creatures. But even so, frogs have a lot to teach us about persistence, longevity and conservation because frogs arose before the dinosaurs, survived whatever killed the "tyrant-lizards" and persist generally unchanged until the present day.
We only have a few species in Humboldt compared to other parts of the U.S. which is good when you are trying to memorize them and add them to your life list!
SPECIES ACCOUNTS by Family
Family Ascaphidae - Ascaphus truei - Tailed frogTailed frogs are small, primitive frogs that breed in fast-flowing headwater streams from sea level to about 6,500 feet from British Columbia to Mendocino County, California. They are dependent on the cold water for breeding and egg-laying.
Males do not call above water, as far as we know the sound would probably not be heard about the sound of the rushing stream. Males and females clasp in amplexus mostly like other frogs and toads. The major difference is that males have a copulatory organ ("the tail" to uptight Victorians) with which they impregnate the females by means of internal fertilization. If they didn't, the fast-flowing water would wash their sperm away before it could fertilize the egg.
Once laid, tailed frog larvae may take two to three years to transform and several years after that to reach full adult size of about two inches. Tailed frogs are fairly common in proper habitat, wandering at least ten to twenty meters (up to 60 feet) and probably more away from the water and into adjacent forest. They can be active all year but are easiest to find in summer since less individuals are up and about at cooler winter temperatures.
Tailed frogs were long thought to be limited to old-growth, they may be tolerant of some disturbance at least in humid coastal areas. They occur with Foothills yellow-legged frogs (Rana boylii) with which they may be confused at first sight.
Tailed frogs can be hard to find. They're rock colored, and blend in beautifully with their background which is usually cold, wet and inaccessible. All that aside, they have magnificent eye-shine and can be found by those making the effort to do so.
Family Bufonidae - Bufo boreas - Western toadWestern toads transform from larvae at about a quarter inch long and grow as big as five inches (snout to vent length). Their muted color scheme of browns and tans features a light colored dorsal stripe. Unlike most other toads, Western toads have no cranial crests; those ridges over the eyes which are such a prominent feature on other species. Like many other toads, however, Western toads have toxic secretions stored in partoid glands. Always wash up immediately after handling a toad, anywhere on Earth.
Western toads mating call is described as light, or "chick-like" and is created without a vocal sac; that little bellows which powers up many other anurans amorous calls. Toad tadpoles transform quickly and toads exploit very shallow, ephemeral wet spots including planter saucers and tire ruts.
Where toad occur, they can be quite common. They have been sighted along the Eel River and at Cannibal Island Beach, breeding in classic tire rut habitat.
Family Hylidae - Pacific treefrog - Pseudacris regilla (was Hyla regilla)Pacific treefrogs are probably the most common amphibian in Humboldt County from sea level to the tops of our local mountains. Their familiar "ribbet" call is heard from wet spots from October through May and frogs hide under all sorts of human objects, from hot tub lids to door-knockers as well as hiding in leaves and more natural things. They occur in a full range of fashion nature colors: from yellow to dark green, they touch just about every spot on the color wheel.
Males make the familiar "ribbet" call to attract females to water to breed. Once laid, the eggs hatch out in a couple of weeks; froglets transform from the tadpoles in about 2.5 months.
Pacific treefrogs are abundant. They are often found associated with human-made/used objects including under front door chalkboards, small pieces of debris, in trees or under hot tub lids and in greenhouses. This species breeds everywhere ponds are available; I've seen them at Russ Park pond at 400 feet elevation as well as the possibly brackish pond at Centerville Beach at plus three feet over the salt water. Outside of Humboldt, I've seen them in the Sierras at 11,000 feet, happily ribbeting away. Pacific treefrogs are habitat generalists, not particularly fussy about habitat. Choruses can be heard from November thru February as the species breeds all winter.
Pacific treefrogs are also heard in many Hollywood movies as the sound tape marked "Frogs" that everyone uses was recorded in Griffiths Park years ago. Herpetologists can laugh at the most inappropriate moments as the familiar "Ribbet!" pops out of speakers when the movie is supposed to be in Asia, Africa or outer space.
Family Ranidae - Northern red-legged frog - Rana auroraThere is considerable confusion about red-legged frogs in the public press. There are two species or two subspecies, depending on your taxonomic system. The southern of the two is called the California red-legged frog (Rana draytonii) and occurs up to approximately the Sonoma-Mendocino county line. The appropriately named Northern red-legged frog (Rana aurora) occurs in Humboldt County and is relatively common along the coastal area including Russ Park pond, Centerville Beach pond, Humboldt Redwoods State Park in Douglas Fir/oak woodland as well as freshwater coastal ponds/sloughs such as those north of Orick.
These large-bodied, small frogs (3 inches) breed in various places from November to April but only for a week or two at each location. Males make a dull, quiet noise rather like "raaa-naa." Females can lay up to 1000 eggs, which clump together, eventually floating until they hatch about a month after they were laid. Froglets metamorphose from tadpoles about five months later.
The "The Notorious Jumping Frog of Calveras Country" was probably a red-legged frog. Some authors lump the two subspecies "as a single species because of the recognition of hybrids from the coast region of northern California." It is possible red-legged frogs were deliberately translocated beyond their original range because 80,000 frogs a year used to be harvested, just for their legs. (Jennings, Mark R. 1985.Pre-1900 Overharvest of California Red-legged Frogs (Rana aurora draytonii): The Inducement for Bullfrog (Rana Catesbeiana) Introduction. Herpetologica, pp.94-103. *and* US Fish and Wildlife Service, 1996. "The California Red-legged Frog: Leaping Towards Recovery?" (On-line). Accessed 14 November 2000 at http://www.r1.fws.gov/sfbnwr/frog~1.html.)
Websites for both species are appended here so you can distinguish between the Northern red-legged frog Rana aurora and the California red-legged frog Rana draytonii.
Family Ranidae - Foothill yellow-legged frog - Rana boyliiAs the common name suggests, this small sized frog has a flash of yellow beneath the hind legs in much the way that some red-legged frogs do. This one might be confused with a female tailed frog, but this one has a horizontal pupil and occurs around slower or flat water which tailed frogs do not. Plus they are most likely to be seen from mid March to late June, during breeding season when they are described as a common river or stream species, common along the Eel River and smaller local streams as well in ditches. Juveniles are reported to be easiest to see in late summer.
Family Ranidae - Cascades frog - Rana cascadaeCascades frogs occur just over the county line from Humboldt in Siskiyou County, so some people include them on Humboldt lists. I've not seen it in Humboldt County. The sites and the call are included because they are possible especially at higher elevations near Siskiyou.
Family Ranidae - Bullfrog - Rana catesbeiana - introducedThis species which was originally restricted to the Eastern U.S. has become nationally cosmopolitan. It's beginning to be considered a non-native invader - a pest on the scale of kudzu and lampreys for it feasts on native fauna wherever it takes hold and is implicated in declines of smaller native species. However, for bullfrogs to become established permanent water is required because their tadpoles require a full year in the water. This feature may be utilized to provide control; merely drain standing water for a while (mimicking summer drought), remove any bullfrog tadpoles found and the adults. They're big enough to be harvested commercially, so they are big enough to be extirpated manually.