There are only five (5) species of toads and frogs in Alaska.
Three of the five are native, while the other two are invasive species. The fact that this number is so little may be attributed to the frigidity of the state.
Alaska primarily consists of ocean habitats, like eelgrass meadows, seamounts (ocean summits), kelp forests, and coral gardens deep in the sea. The amphibian population usually prefers warmer areas and goes into hibernation in the coldest months of the year.
They possess other similar characteristics and there are differences between them too. These animals look alike, with four legs, no tails, widely spaced eyes, and enlarged parotid glands. Their forelegs have four digits while their hind legs have five.
They are able to see a wide range. With their external eardrums (tympana), they are able to detect sounds that are important for their survival, like the mating calls and other calls of conspecifics (individuals of the same species).
Their skin is colored to match their environment and prevent predators from easily spotting them. This dorsal skin is generally warty, rough, and dry in toads, but smooth and moist in frogs. Toads produce poisons from their skin to deter predators, and some frogs do as well.
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Frogs move by jumping or leaping, and they have long, slender legs for this. Toads walk or hop, and their legs are shorter and stockier. Both animals have long tongues to catch their common prey — insects and other invertebrates.
They are solitary, living alone except in the breeding season.
During this period of the year, males gather at breeding ponds or pools and make use of advertisements or breeding calls to beckon out to females.
If the females are interested, they meet males at the ponds to mate. Fertilization is external in most, as females release their eggs into the water, and then males release their sperm to fertilize them. Only tailed frogs use internal fertilization.
Both animals go through three stages of metamorphosis. After fertilization has occurred, eggs grow into larvae (tadpoles), and then into adulthood. This article centers on the adult species of toads and frogs in Alaska.
Frogs and toads are primarily insectivorous. Some larger species of these anurans may feed on smaller species and even conspecifics. Common predators include birds, fish, larger amphibians and reptiles, otters, raccoons, and sometimes humans.
Information provided in this article includes the species’ geographic range, their preferred habitats, morphological features, behaviors, and additional anti-predator techniques. Except otherwise stated, these species are not endangered.
Species of Frogs in Alaska
1. Columbia Spotted Frog
- Family: Ranidae
- Scientific Name: Rana luteiventris
- Other Names: N/A
- Adult Size: 5.08 to 10.16 cm (2 to 4 in)
- Lifespan: 10 or more years
Columbia spotted frogs are native to North America, and found in Canada and the United States. States and regions that they occur in include Yukon, British Columbia, Alberta, Montana, Wyoming, Idaho, and Oregon.
Frogs of this species prefer to live in still and slow-moving bodies and sources of freshwater. As a result of this preference, they are mostly found in ponds and lakes and along slow-moving streams.
The Columbia spotted frog is an average-sized frog. Its back could be tan, brown, or olive green in color. Dark and irregularly shaped spots can be noticed across the frog’s back, legs and sides.
The underbelly of this frog is a bright color, usually white, off-white, or yellow. Along its upper lip is a yellowish or white line. It has a narrow snout, shorter legs, and webbed feet. Rough folds can be found on its dorsal skin.
Columbia spotted frogs are diurnal. They are very aquatic and rarely seen away from the water. They are among the three species of frogs and toads that are native to the state of Alaska.
The call of a frog of this species is low in pitch, sounding like rapid knocking or clucking. When threatened or attacked, the frog is able to startle its predator with an alarm call which is a 6-second shriek.
2. Northern Red-Legged Frog
- Family: Ranidae
- Scientific Name: Rana aurora
- Other Names: N/A
- Adult Size: 5 to 13 cm (2 to 5.25 in)
- Lifespan: up to 15 years in captivity
The red-legged frog is native to Oregon and California.
There are also individuals in British Columbia, Canada. Two subspecies exist Rana aurora aurora (Northern red-legged frog) and Rana aurora draytonii (California red-legged frog).
They occur around the banks of still or slow-moving ponds and streams. They prefer habitats that have vegetation to provide them with cover from predation, the heat of the sun, and the cold of the winter.
Red-legged frogs are usually reddish brown or gray in color, with several undefined splotches on their backs in a darker color. There is a light stripe on their jaw, with folds on their back and sides also.
Underneath them, their venter is yellow, and there are red-colored streaks on the ventral part of their lower abdomen and back limbs. Their toes are not fully webbed. Differences exist between the subspecies.
The northern subspecies lack vocal sacs while the California species have paired vocal sacs. Northern red-legged frogs have smooth, thin, and unspotted skin, while the bigger California red-legged frogs have rougher skin with light-centered spots.
Differences exist between sexes as well. Females grow to a larger size than males do. Males have larger forearms and swollen thumbs. Northern red-legged frogs are an invasive species in the state of Alaska.
Like most frogs and toads, they prefer to live alone until the reproduction season. They are diurnal. They flee from a predator’s attack by swimming to the depths of water, as an anti-predator technique.
3. Pacific Chorus Frog
- Family: Hylidae
- Scientific Name: Pseudacris regilla
- Other Names: Northern Pacific tree frog, Pacific tree frog
- Adult Size: 1.9 to 5 cm (0.75 to 2 in)
- Lifespan: N/A
Pacific chorus frogs have been found living in Mexico, Canada, and the United States. They can be found in US states like Alaska, Arizona, California, Nevada, Oregon, Utah, and Washington.
As their name suggests, they are found in the Pacific Northwest region of North America, mostly on land. They live in dense vegetation, usually around streams, ponds, swamps, springs, and several other damp areas.
A distinct Y-shaped mark is present on Pacific chorus frogs, between their eyes. Black spots are visible on their dorsal skin and legs. Two black stripes run across their backs, one from each shoulder and through each of the eyes.
Although largely terrestrial, these frogs are biologically adapted for climbing. The ends of their toes have sticky circular disks on them. Female frogs are larger than their male conspecifics.
Dorsally, each individual pacific chorus frog is colored differently from others and has various colors on its own skin. Its color is any shade from lime green to brown. The shade of its skin can change depending on humidity and temperature.
This species is invasive in Alaska. They are nocturnal frogs whose call is a deep and loud croak, a rapid “cree-creek”.
They can change color and camouflage from predators, but they cannot willingly change their dorsal coloration to match their surroundings.
4. Wood Frog
- Family: Ranidae
- Scientific Name: Lithobates sylvaticus
- Other Names: Rana sylvatica, the frog with the robber’s mask
- Adult Size: 3.8 to 8.2 cm (1.5 to 3.25 in)
- Lifespan: 3 to 5 years in the wild
The wood frog is another species of frog in Alaska.
It is commonly distributed across North America. It can be found in several places within the United States and Canada.
This frog lives mostly on the ground or around trees, but it can also be found in marshes, swamps, meadows, and mixed forests. Woods frogs leave these primary habitats of theirs to breed in semi-permanent water bodies.
A wood frog has mask-like markings across its eyes. These markings are black patches from each tympanum to the base of each of its forelegs. A white outline is also present, across its upper lip.
Frogs of this species come in diverse shades of gray, green, brown, tan, and rust. A mid-dorsal fold is also present, running down their backs in a bright yellow-brown color. Ventrally, the frogs are white.
There is sexual dimorphism in wood frogs. While males are smaller in size with the ventral part of their legs colorful, females with their white bellies fading to a yellow-orange pallor towards the legs. The females are however more brightly colored dorsally than the males.
Wood frogs are more diurnal, actively scrounging and feeding during the day. Their call sounds much like the clucking of a chicken. They are a species of frogs native to Alaska.
They produce poisons to irritate predators in case of capture or attack. When captured, the wood frog lets out a piercing cry. It may startle the predator and annoy it enough to let the frog go.
Species of Toads in Alaska
5. Western Toad
- Family: Bufonidae
- Scientific Name: Anaxyrus boreas
- Other Names: Bufo boreas, alkali toad, boreal toad, California toad, Southern California toad
- Adult Size: 5.6 to 13 cm (2.2 to 5.1 in)
- Lifespan: 9 to 11 years
The western toad is the only species of toad found in and native to Alaska.
These toads are found in other states of the US like California, Idaho, Montana, Nevada, Utah, Washington, and Wyoming. They also occur in British Columbia, Canada, and parts of Mexico.
The habitat of choice for this toad is mountainous areas, as it has been found in elevations as high as or higher than 10,000 feet. It can also occupy desert streams and springs, mountain meadows, and grasslands.
Dorsal coloration is usually dusky gray or greenish on this toad. A stripe runs down its back, and this line is white or cream in color. Irregularly shaped dots in black or some other dark color can be noticed on the dorsal surface of the toads.
The parotid glands of western toads are oval and widely spaced. They are larger than the toad’s upper eyelids. Frogs of this species lack cranial crests.
Their venter is white with some mottling on its surface. Males and females are slightly different. Males have smoother skin, less spotting on their backs, and nuptial pads on their toes for gripping the females during the breeding season.
The dorsal skin of the females is rougher in texture than that of the males. They have many blotches on their dorsal skin and lack nuptial pads on their toes. Western toads are both diurnal and nocturnal.
The call of this toad species is quite peeping likened to the sound of little chicks. Like other toads, their anti-predator mechanism is the poison produced by their paratoid glands and warts on their skin.
What do frogs do in Alaska in the wintertime?
In the winter, frogs in Alaska and elsewhere go into hibernation. This is a sleep-like state which helps them survive the winter without moving around looking for food and warmer habitation.
How many species of frogs live in Alaska?
Four (4) species of frogs live in Alaska. Out of this number, the Columbia spotted frog and wood frog are native to the state. The northern red-legged frog and Pacific chorus frog are invasive species in Alaska.
Only two species of frogs and one species of toad are native to the frigid US state of Alaska. Two additional species of frogs can be found in the state. None of the species is endangered in the area.
The only poisonous species of frog in Alaska is the wood frog. Because they are not poisonous or toxic to humans, the other three species can be kept as pets. The western toad produces harmful secretions so it is not a good option for a household pet.
Frogs and toads in this region are able to withstand the extreme cold of Alaska, with the wood frog being the most widely distributed. Frogs and toads may be found with certain abnormalities in Alaska, and their habitats may sometimes dry up due to the increased temperature for most of the year.