Spotted Salamander Natural History
With the first warm rains of spring after the ground has thawed, the salamanders come out of hibernation and make a nocturnal migration to the vernal pool from which they developed. They may have to cross patches of snow and arrive at a pool still mostly covered with ice.
In areas where habitat is fragmented, salamanders and other amphibians may need to cross roads. Significant mortality may be caused by road traffic.
Volunteers in some areas helps salamanders and wood frogs safely cross roads. Do not do so if you will endanger yourself.
If visiting a vernal pool during migration nights, carry a light and avoid stepping on animals. They can be difficult to see.
Male and female spotted salamanders may be identified during breeding season by differences in the cloacal vent and the size of the abdomen.
Males arrive at the pool first. When the they enter the water, they "congress" and go through a mating dance. The males swim about, nuzzling each other and coming to the surface to gulp air. They produce a field of spermatophores.
As congressing progresses, the males will produce spermatophores which are pyramid-shaped plugs of mucus with sperm on them. Each male will produce many spermatophores which might look like bread crumbs on the bottom of the pool. The female places her vent on one or more spermatophores and sperm enter her cloaca. The eggs are internally fertilized.
Egg laying takes place a few days after the female visits spermatophores. The eggs are released as a compact mass which is attached to vegetation. The mass swells as it takes on water.
Spotted salamander egg masses may be clear, somewhat cloudy, or almost opaque.
An egg mass will be tennis ball sized or smaller.
Females lay the eggs in communal clusters, usually is the best area of the pool for development. Conditions sought include, maximum sunlight, adequate water depth until hatching, and attachment sites for the mass.
One advantage of group egg laying, is the concept of "predator satiation". A predator finds such an abundance of egg masses that it does not eat any mass completely. Predators include caddisfly larvae and spotted turtles and others.
By May, the masses are often green from a symbiotic algae (Oophila amblystomatis). Within each egg can be seen the growing salamander larva. Egg masses are evidence of breeding which can be found throughout April, May and into June (variable according to location and weather).
When pools dry prematurely or eggs were attached too high for future conditions, masses end up exposed. The jelly mass can retain water for a couple of weeks during which time water might rise.
Within each egg, the embryo grows for several weeks.
Upon hatching, the small salamander larva has bushy gills, no legs and a pair of balancers below the gills. The immediately begin feeding on small organisms in the pool.
As the larvae develop, the lose the balancers and develop four legs. They both swim and walk about on the pool bottom.
Spotted larvae feed on daphnia, small insect larvae (chironomid midge, etc.) oligochaete worms, and other small invertebrates.
Spotted larvae are eaten by predatory insects (predaceous diving beetles, their larvae [above], and giant water bugs), other ambystomatid larvae, as well as turtles.
Throughout July and August (depending on a number of factors including water level and temperature) larvae lose their external gills and emerge from the pool. Spots develop around this time but the larva may emerge with no spots and take several weeks for them to appear.
They often remain close to the pool and can be found under logs, moist leaves, moss, etc. They may not show the yellow spots until a few weeks after emergence.
The spotted salamander lives in the moist uplands near a vernal pool. The live under logs and vegetation, in animal burrows, and on some moist night emerge to feed. They ear various invertebrates including worms, centipedes, crickets, spiders, etc.