About Ambystoma gracile (Baird, 1859)
The egg mass of Ambystoma gracile is very firm, with a texture similar to a brain, and a jelly layer surrounding the entire mass. Individual eggs measure 2 mm in diameter, and the entire egg mass is roughly the size of a human fist. Egg masses are laid in water between 0.5 and 2 meters below the surface. Hatchlings are 1 to 35 mm long, and have feathery gills on the sides of the body. Juveniles measure 16 to 105 mm in snout-to-vent length. Adults measure 40 to 107 mm in snout-to-vent length.
Spotted individuals of this species are found in the northern part of the species' range. A dividing line at 51°N latitude separates the two recognized subspecies: A. g. decorticatum occurs north of the line, and A. g. gracile occurs south of the line. Populations with neotenic adults are widespread across the range. The frequency of gilled (neotenic) adults increases with altitude: adults at low and intermediate altitudes are almost entirely terrestrial, while adults at very high elevations are mostly neotenic. A well-documented paedomorphic population of Ambystoma gracile lives at Crater Lake, Oregon, where this population shares its habitat with Taricha granulosa.
Terrestrial adult Ambystoma gracile live in mesic habitats, ranging from grasslands to mesophytic forests. Most terrestrial adults are fossorial, and are usually active on the surface only during fall rains and spring migrations to aquatic breeding sites. They can occasionally be found under logs and other surface debris outside of the breeding season. Adult salamanders feed on small terrestrial invertebrates, including insects, worms, and arachnids. Larvae and juveniles feed on aquatic invertebrates, including snails, worms, and tadpoles.
