Six amphibian and six reptile species inhabit Lassen Volcanic National Park. They are often considered together because both are poikilotherms, animals that lack the ability to generate their own body heat, relying instead on their environment to regulate body temperature. Amphibians spend the early part their life cycle in water as larva before metamorphosing into adults that live on land. Toads are a good example. As tadpoles, they are restricted to aquatic environments, but spend almost all of their time on land as adults. In contrast, reptiles are generally terrestrial throughout their life cycle. Amphibians are also characterized by moist, highly vascularized skin while reptiles are typically covered by scales.
Lassen’s amphibians can be divided into two groups - anurans and caudates. Anurans are frogs and toads. Caudates include newts and salamanders which have tails and resemble lizards in appearance. Caudate amphibians spend most of the year hidden to avoid the heat. They live under rocks and rotten logs or underground in damp crevices and burrows and typically emerge in autumn after the first soaking rain. Lassen’s lone newt species, the rough skinned newt, is the park’s most visible caudate. They move like a lizard in slow motion and are often observed in early spring crossing roads or trails on their way to breed in streams.
Lassen’s anurans include the western toad and two species of frogs. The most common frog species is the ubiquitous Pacific treefrog. Found at nearly all elevations in nearly all habitats, this diminutive frog is the species most often heard calling around meadows and ponds in the spring. The other frog species is the Cascades frog. This species was once prevalent in the park but now only a few remain. The reason for the decline is unknown and further studies are needed to determine the causes for the decline.