Salamander Migrations

In late winter and the early spring, several species of amphibians migrate to suitable breeding habitat. For species of mole salamanders (family Ambystomatidae), this can be an arduous journey. As the name suggests, members of Ambystomatidae are highly fossorial, spending most of their adult lives below ground, concealed among roots or beneath logs on the forest floor. However, the “call of the wild” drives them from their subterranean domicile to ponds, marshes and lakes.

One species of mole salamander, Jefferson salamander (Ambystoma jeffersonianum), migrates in late winter even across the snow; others wait until later in the year, when the early spring rains penetrate the soil spurring the terrestrial forays. Amphibian eggs do not have a protective outer covering and so must be deposited in moist areas to prevent desiccation. Ephemeral pools (containing water for only a portion of the year) provide optimal amphibian breeding habitat because, being temporary, it prevents the presence of certain predators (fish) from devouring the eggs, larvae and even adults. The eggs are encased in a gelatinous layer that gives the egg mass a “halo” appearance. Egg clusters are submerged attached to vegetation and/or sticks in the water. The larvae hatch a few weeks after deposition. The aquatic larvae feed on small insects and particulate matter until they develop limbs and migrate out of the pools to find suitable habitat and mature to adults.

Today's photo was taken by WPC's Endangered Species Biologist/Herpetologist Ben Jellen. Also pictured today (inset) is an adult spotted salamander (Ambystoma maculatum) taken by WPC Volunteer and Amateur Herpetologist Ray Shearer. The photograph of the underwater eggs is enlarged. For size comparison, each egg is about 1 centimeter (1/3 inch) in diameter and the oval egg masses are roughly 5-10 cm (2-4 inches) in diameter; while the adult salamanders are usually in the range of 15-20 cm long (6-8 inches). This is the most common species of the mole salamander group in Pennsylvania. It can be regularly seen during its migration to spring breeding pools, or it can be found in those pools for a few weeks. Otherwise it is only occasionally encountered, usually when someone turns over a large log or discarded lumber, or is digging into the ground. Spring migration from forests to the breeding pools often takes place on the first early spring night when the air temperature is around 50 degrees F. and it is raining. Predicting the movement can be confounded by vacillating warm and cold periods, as we're experiencing this year.

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