Sanctuary Amphibian Monitoring

Rana Clamatans

Amphibians are an ancient class of vertebrates that include frogs, toads, and salamanders. Most occur in freshwater habitats and moist forests. 

Life Cycle

Almost all amphibians lay their eggs in aquatic habitats, such as small ponds, ephemeral pools, and freshwater swamps. The eggs hatch into tadpoles (larvae). At this stage in their development, they have gills for breathing, no legs, and tails with a fin to aid in propelling them through water. 

After a period of development that may range from a few weeks to several years depending upon the species, they metamorphose into adults, losing their gills and gaining walking legs in the process. Frogs and toads also gradually lose their tails as they mature. 

Amphibians in Massachusetts

Twenty-one species of amphibians have been recorded in Massachusetts, divided roughly evenly between salamanders and frogs. 

  • Four are on the Mass Heritage list of rare and endangered species
  • Three additional species are considered of conservation concern, based on the Division of Fishery and Wildlife’s State Wildlife Action Plan (SWAP). 
  • The four state listed species all depend on ephemeral (temporary) pools for breeding, a habitat that is often not as well protected by wetland regulations as permanent wetlands.

Where to Find Amphibians

Vernal pools

These ephemeral pools that form as a result of snowmelt and spring rains are critical habitat for a number of amphibians, including some that are state-listed.

  • These pools dry out by mid-summer, insuring that they do not support fish, which would otherwise feast on the eggs and newly hatched tadpoles. 
  • Amphibians that breed only in vernal pools are called obligate vernal pool amphibians. 
  • A number of invertebrates, most notably fairy shrimp, are also obligate vernal pools species. 

Swamps and Marshes

Some species of amphibians never venture far from wetlands even as adults. These include bullfrogs, green frogs, and pickerel frogs. 


Adult amphibians can frequently be encountered on the damp forest floor, particularly under logs and leaf litter. These include wood frogs and spotted salamanders, two species that breed in vernal pools. 

  • A few, such as the spring peeper whose sweet whistling is one of our most cherished signs of spring, can climb up woody vegetation.
  • Almost all return annually to water to breed.