Opportunities / Science

Eggs: Frog or Salamander?

Wetland Vernal Pools – nests for frog and salamander eggs

Wood Frog egg masses

Wood Frog egg masses

Vernal pools are pools in the forest which dry for portions of the year.  Wood Frogs and Mole Salamanders rely on vernal pools for the survival of their young because these pools have no fish to eat them.  From late April to Mid-May, Wood Frogs and Mole Salamanders travel to vernal pools, breed, and lay big globs of eggs, called “egg masses”, within the pools.  It is relatively easy to identify Wood Frog egg masses.  Wood Frogs typically lay egg masses in a group, often near the surface, and attached to a branch.  The outer layer of the egg mass takes shape of the individual eggs, so the egg mass is bumpy. Frog egg masses do not have the protective outer gelatinous layer.

Spotted Salamander egg masses

Spotted Salamander egg masses

Salamander egg masses have a second, outer, layer of jelly.   Salamander egg masses are usually laid alone or in small groups.  The most common is the Spotted Salamander and its egg mass is smooth and firm to hold and contains 50-250 eggs.  Telling the difference between Spotted- and Blue-Spotted or Jefferson Salamanders is more challenging.  Blue-Spotted egg masses contain 1-30 eggs and are extremely loose; if you were to pick up a blue-spotted salamander egg mass, the mass would ooze through your fingers.  Jefferson Salamanders lay long egg masses, with 10-60 eggs, attached to vegetation and are relatively firm, with a bumpy outer surface.  Jefferson and Blue-Spotted Salamander eggs have two membranes very close together around the egg, while Spotted Salamander eggs have the membranes spaced out.  To learn more, see: http://beec.org/wp-content/uploads/2009/11/Egg-Mass-id-web.pdf or A Field Guide to the Animals of Vernal Pools” by Leo Kenney and Matthew Burne, 2009.

It is fun to search for vernal pools and amphibian eggs in the springtime.  Share your discoveries with: VT Reptile & Amphibian Atlas: www.vtherpatlas.org. Contact your local nature center for more fun: http://www.northbranchnaturecenter.org/AMP.htm in Montpelier and http://beec.org/ in Brattleboro.