A fall nor’easter just hit south-central Connecticut with 4 inches (102 millimeters) of rain and strong, gusty winds. Storms are life-giving for a little known and seldom seen amphibian, the Marbled Salamander (Ambystoma opacum).
Hidden among the leaf litter and under logs around shallow, fishless vernal pools, these stocky, 3- to 5-inch (75- to 125-millimeter) salamanders are fossorial. They spend most of their time in subterranean burrows and travel around on rainy nights feeding on earthworms, snails, slugs, crickets, beetles, ants, and other invertebrates. They are in a group appropriately called mole salamanders. The larger Spotted Salamander (Ambystoma maculatum) is a relative.
Although the related Spotted Salamander and most other amphibians breed in the late winter and early spring, the Marbled Salamander is rather unique. It lays its eggs in autumn. It is also one of the few amphibians in this salamander group that breeds on land. In September or October, males gather in dried-up areas next to vernal pools and other shallow, freshwater wetlands. When she arrives, a male will court a female by rubbing against her. Then he’ll deposit a sperm packet, a spermatophore. The female inserts the spermatophore into her cloaca to fertilize her eggs. She’ll lay between 50 and 200 eggs.
The Marbled Salamander is among the few amphibians that display parental care. The female often stays with her eggs, brooding and protecting them from predators until storms like the one we just experienced fill vernal pools and water inundates the nest site. Once the nest floods, the eggs are on their own. A few days later, they hatch. The larvae take between two to nine months to metamorphose. Juveniles need another 15 months to mature after they crawl out of the water. They are relatively long-lived, with a life span of five to 10 years or more.
The carnivorous larvae first feed on zooplankton throughout the winter. As they grow, they graduate to larger prey. By the time Spotted Salamanders come to vernal pools to breed around March, Marbled Salamanders are already one of the top predators in these pools. In addition to aquatic insects, Marbled Salamander larvae will even feed on hatching Wood Frog (Lithobates sylvaticus) and Spotted Salamander larvae.
Although locally common in the right habitat in Connecticut, the habit of Marbled Salamanders of staying near the area where they were born makes them particularly vulnerable to loss of forested wetlands. Being in an isolated population can hinder their ability to recover from localized declines. It is vitally important that we protect wetland and forest habitats, and create and keep wildlife corridors between wild lands.