|Common Name:||Pacific Tailed Frog
Rocky Mountain Tailed Frog
|Scientific Name:||Ascaphus truei
|Status (B.C.):||Blue (Pacific)
Red (Rocky Mountain)
|Status (COSEWIC):||Special Concern
In 2000, the Tailed Frog was split into two species. The coastal species
Ascaphus truei, and is called the Pacific Tailed Frog. The Kootenay
species is now called Ascaphus montanus,
the Rocky Mountain Tailed Frog.
At a Glance
The Tailed Frog is a remarkable little frog, unique to B.C. in Canada. It is a
small frog, 2.5 to 3 centimetres from nose to rump. Adults are usually tan or brown
in colour although some may be shaded green or red, or even entirely black. The skin
has a rather grainy appearance. Tailed Frogs have vertical pupils, no external
tympanum (the round "ear" visible on other frogs), and are voiceless. The toes on
the hind feet are flat and wide, especially the outer toes, and these can be used
to distinguish Tailed Frogs from other frogs and toads.
The most remarkable feature of Tailed Frogs is the "tail" which gives the species
its common name. The "tail," which only males have, is actually a copulatory organ
used to fertilize the eggs of the female internally. While newly metamorphosed frogs
of other species may have a remnant tail for a few days, it is a different colour
from the body, while the "tail" of the Tailed Frog is the same colour and texture
as the frog's back.
Unlike most frog species, the tadpoles of Tailed Frogs are easily identifiable,
having a very large sucker-like mouth. Hatchlings are almost transparent, while older
tadpoles are dark mottled brown or black, often with a white spot on the tip of the tail.
Tailed Frog tadpoles are found clinging to stones in streambeds.
Home Sweet Home
The Tailed Frog likes clear, cool mountain streams. Small channels without fish and
with shading plants and trees are favourite locations. The type of streambed is also
important. Tailed Frogs are usually found in streams with large stones, cobbles, and
stable boulders, which they can use for shelter from the rapid current. Some quieter
side pools are also needed, so that eggs and hatchlings won't be washed away. The
streams must contain water year round, since Tailed Frog tadpoles need to stay in the
water for a long growth period. Adult Tailed Frogs often hide and hunt on the stream
banks, but need to stay moist since they are much less able to withstand drying than
Although young Tailed Frogs disperse from their hatching sites, once they
reach adulthood they will usually not move far from their chosen stream. Home
Sweet Home indeed!
This is the Life
Tailed Frogs grow very slowly, taking up to four years in high mountain populations for
the tadpoles to metamorphose. It takes several more years for the froglets to become sexually
mature. Tailed Frogs may live 15 to 20 years, making them one of the longest-lived frogs in
Mating takes place in the fall, in streams, after a courtship ritual. Females mate only
every second year. The male clasps the female and inserts his "tail" into the female's
cloaca in order to inseminate her. She stores the sperm inside her body until the following
summer, when she lays strings of eggs underwater, attaching them to the base of a large stone.
Hatchlings emerge six weeks or so later, and overwinter in the quieter waters; they move
out into the stronger current areas once their oral suckers have developed enough to let them
cling to the rocks.
What’s on the Menu?
Tailed Frog tadpoles scrape algae from submerged rocks, and every once in a while will
also swallow small insects and grains of pollen that fall into the water. Adult Tailed
Frogs eat insects, snails and other small invertebrates, using a "sit and wait" strategy
for hunting. The Tailed Frog is not able to grab prey with its sticky tongue as other frogs
can - its tongue is attached closely to the floor of its mouth, so it cannot flip out its
tongue to grab insects. Instead, the Tailed Frog must pounce on its prey and grab the meal
with its mouth.
Where and When
Tailed Frogs are found from western B.C. south as far as California, and as far east
as northwest Montana and Idaho. In B.C., they are found in the mountains on the coast
and in small patches in the Kootenay. Clear, cold, swift headwater streams are the best
places to look for Tailed Frogs. These frogs are found in or near their home streams
How Are They Doing?
Tailed Frogs are vulnerable to human activities. Forestry activities and road building
can damage breeding streams by removing cover vegetation, disturbing streambeds and contributing
to siltation. Streams may become too warm for tadpoles if the shading trees are removed.
Pacific Tailed Frogs are relatively widespread in the coastal mountains. They have been
placed on the provincial Blue List, and have been designated by the Committee on the
Status of Endangered Wildlife in Canada (COSEWIC) as Special Concern. The Kootenay Tailed
Frogs have a much smaller and more restricted range, and have been placed on the provincial
Red List, and designated by COSEWIC as Endangered.
How We’re Helping
Tailed Frogs are protected from being killed, collected or harmed under the provincial
Wildlife Act. Under the Identified Wildlife Management Strategy of the Forest Practices
Code, Wildlife Habitat Areas can be established for critical breeding habitats. Scientists
are studying the effects of forestry activities on the Tailed Frog.
How You Can Help
Adult Tailed Frogs are vulnerable to crushing if humans trample stream edges,
overturning the stones that shelter the frogs. Tadpoles may be trampled or smothered by
stirred-up silt if people or vehicles cross the streams. Accordingly, it is not a good
idea to go out searching for them. However, if you do happen to come across Tailed Frogs,
please notify B.C. Frogwatch or contact the Conservation Data Centre in Victoria.
You can also help by learning more about these frogs and about
other amphibians, and by teaching others about them.
- The closest living relative of the Tailed Frog is a species
found only in New Zealand
- When hunting, these frogs "overshoot" their prey, gaping
their mouths open as they pass the prey, then snapping it
up as they recoil to a sitting position. The hind toes never
leave the ground, while the front feet are held to the sides.
- Tailed Frogs do not call. They have no eardrums, though they may be
able to sense vibration in the water.
Photo © Wally Edwards. No reproduction or distribution without permission.