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Northwest Wildlife Online
Order Anura: Frogs and Toads
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Color variations of the Pacific Tree Frog (Hyla regilla): brown, green, and copper gold. The dark strek running from the nose through the eye is the key to identification of the frog. Despite its name Pacific Tree Frogs spend far more time on the ground than in trees.
Beautiful example of a female Bullfrog, Rana catesbeiana, courtesy of Thomas Dahlen, Mooserun Photography. The Western Toad (Bufo boreas) on the right inhabits a wide variety of living conditions and ranges from Alaska to New Mexico, but sightings of this large toad are decreasing.
Four Families and 12 Species of Order Anura represent wildlife in the Northwest:
Family Leiopelmatidae - the Bell Toads:
Tailed Frog (Ascaphus truei) - 1-2 inches long. Unique among frogs for internal fertilization. Males possess a copulatory organ that looks similar to a vestigial tale. Likes clear and cold streams and is found in high elevations. Color ranges from a metallic brown to dark green (see photos below).
Family Hylidae - the Tree Frogs:
Pacific Tree Frog (Hyla regilla) - 3/4 - 2 inches. Wide color variation; distinguished by the dark eye stripe (see above photo). Very common from sea level to mountain elevations over eleven thousand feet.
Western Chorus Frog ( Pseudacris triseriata) - 3/4 - 1 inches long. One of our smallest frogs the Western Chorus Frog does not possess toe pads. Likes ponds and swamps. I have found them out in very early spring. (See photo below).
Family Ranidae - the True Frogs:
Red Legged Frog (Rana aurora) - 13/4 - over 5 inches. Reddish color under legs and abdomen. Prominent dorsolateral fold. Similar in appearance to the Spotted Frog, but larger and with a less prominent back ridge. The California Red Legged Frog is famous as Mark Twain's celebrated Calveras County anuran.
Foothill Yellow Legged (Rana boylei) - 11/2 - 3 inches. Distinct yellow color on the underside of the legs that extends to the stomach. Topside color tends to match surrounding environment.
Cascades Frog (Rana cascadae) - 13/4 - 3 inches. Aptly named, this frog ranges to elevations above the tree line. Brown to olive green with black spots that resemble sprinkles of black ink on its back.
Bullfrog (Rana catesbeiana) - Up to 8 inches long. The largest of the True Frogs. Very distinct heavy bodied frog. Often leaps to safety while emitting a high pitched, and startling, birdlike squawk. The one in my backyard pond often startles visitors by its size.
Northern Leopard Frog (Rana pipiens) - 2-4 inches. Green to brown color with distinct spots on the back; white underneath; very prominent dorsolateral fold. Very well adapted to cold climates. I used to find a lot of these guys in New York. Leopard frogs are know for making zig zag jumping patterns as flee to safety.
Spotted Frog (Rana pretiosa) - 13/4 - 4 inches. Bullfrog like body (although much smaller). Reddish color on sides and bottom; black splotches or spots on back and legs. Has a distinct light colored jaw stripe.
Wood Frog (Rana sylvatica) - 11/4 - 31/4 inches. Truly a frog of the north, the Wood Frog ranges into Alaska. Light brown color with a d distinctive dark brown mask ending behind the ear drum.
Green Frog (Rana clamitans) - 11/4 - 4 inches. Green to brown frog. An eastern transplant Green Frogs are very adaptable and can be found from swamps and marshes to higher elevations (see photo below).
Family Bufonidae - the True Toads:
Western Toad (Bufo boreas) - 2 - 5 inches. Tan to greenish (see above photo). The Western Toad inhabits a wide variety of environments, but is reportedly becoming rare. Now a protected species.
Woodhouse's Toad (Bufo woodhousei) - 13/4 - 5 inches. Prominent cranial crest with distinct, whitish dorsal stripe. Inhabits a wide variety of environments within its small range.
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More About Frogs and Toads
How could anything be less interesting than common frogs and toads? Let me disabuse you of this absurd notion. Imagine yourself as an adult. You break out the old photo album to check out some childhood pictures. You flip open the cover and there you are - just a wee one. Yet in the photo you bear no likeness to your present self at all. You have no limbs, your eyes are almost microscopic, and your mouth is a tiny suckerfish with a rasping, snail like tongue. On top of this your youthful self is possessed of only two body parts: a vastly oversized head attached to a tail. Compared to your adult image you look like a monster.
I use this ridiculous analogy to drive home a point about how some animals that we view as common place actually have complex and bizarre lives. Can you imagine your own experience if you began a limbless existence and then suddenly sprouted legs? Can you imagine your head swelling to an unnatural size while your mouth and eyes expanded to frightening proportions? Kind of makes you look at frogs and toads in a new light.
The Western Chorus Frog, Pseudacris triseriata, is a native son. The larger Green Frog, Rana clamitans, is a transplant from the East Coast. This photo was taken in Mount Ranier National Park at an elevation of 4,000 feet.
A Tailed Frog, Ascaphus truei. The distinctive "tail" is actually for copulation; the only frog in the world known to have such an organ, but a very effective breeding adaptation for the cold mountain streams it prefers. The above photos show the color variations of the animal. I found these guys at an altitude of at least three thousand feet. The air temperature was in the sixties and the stream water must have been fifty degrees or below - yet these little fellows were still active. Those red fingernails are not mine - they belong to my wife.
There are about 2800 species of known frogs and toads. Of all the back boned animals the Anurans go through the most complete metamorphosis. Watching this transformation is a thrill. Although many of us have seen tadpoles and frogs few have taken the time closely study this change. If you have not done so I highly advise catching some of the little guys this spring and raising them to adulthood. Children (and adults) will find the process amazing.
North America is fairly blessed with anurans. Of the 16 families known worldwide, 9 live right here in our country, and about half of those are represented in the Pacific Northwest. Looking at a frog a couple of things are immediately obvious. There is no real neck, the eyes are large and bulbous, and there are no external ears. Anuran ears are internal and communicate with the outside world through the tympanum, the large circular marking behind the eyes.
Frogs and toads are a vociferous bunch and most use conspicuous calls to mate, defend territory, or signal emotion. Bullfrogs emit a startlingly loud, bird like chirp when disturbed. (The big guy in our pond has startled more than one visitor.) The wide variety of trills and calls of Tree Frogs are wonderful sounds. In fact, frogs and toads have a sound for just about everything. Sometimes, in the frenzy of spring mating. an occasional mistake is made and a male will mount another male. The offended male quickly delivers a particular croak for the incident, saying, in effect, "Hey, get off me!"
All adult anurans are carnivores and will eat just about anything they can stuff into there considerable mouths. They are sight hunters attracted by movement and catch prey by use of a long sticky tongue. Watch a frog swallow and he will inevitably close those bulbous eyes. As the eyes sink into the head they place pressure on the throat and aid in swallowing.
Nearly all anurans return to water to breed and lay eggs, although this is not an iron clad rule. A few rare species are completely adapted to a terrestrial life and lay eggs in spots with adequate moisture. As a general practice, though, most frogs and toads are born in the water in eggs that are fertilized externally. Males clasp the females from behind, an embrace called amplexus. The little guys hatch, begin life in the tadpole stage, and then begin their amazing transformation. The tadpole stage does not generally last more than a single season, but bullfrogs may remain in this stage for three years.
Anuran skin is particularly fascinating. Specifically designed to soak up and excrete moisture, it mildly to extremely poisonous in some toad species. As far as I know none of our Northwestern toads fall into the dangerous category.
For all of our vaunted Northwest water and rain we have just five families of frogs and toads. The largest, the bullfrog, actually an imported species. I've seen some that I estimate at two pounds, but I've seen Western Toads that could give a bullfrog a run for its money. The smallest are the inch and quarter long Chorus Frogs.
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