During the winter, spotted salamanders stay burrowed beneath leaves and logs or huddled in the rocks. But when stimulated (usually in mid- to late January) by the right combination of temperature, humidity, and darkness, they gladly forsake this safety and comfort to join in a mass migration, trudging doggedly along at twenty to forty feet per hour. Their goal is simple: to reach the breeding ponds of Shades Creek by the most direct route possible. Those hibernating nearby may reach the ponds that same night; others will divide the journey into sections, holing up when overtaken by daylight, dryness, or cold.
Males, responding to the environment more quickly and moving more rapidly, reach the ponds in advance of females. There they congregate in shallow depressions, rolling and tumbling and thrashing about in a prenuptial frenzy. When a female appears, a male nudges and rubs her, depositing his spermatophore-a stump-shaped mass of jelly surmounted by a white cap of sperm-a short distance away, then returning and leading her to it. The female, if interested, squat over the structure, allowing the sperm to pass into her cloaca. This "dance" is then repeated, either with the same or different partners, and several days later the fertilized eggs are released. Their reproductive task completed, the adults head slowly back to their home territories.
Eggs are deposited in compact masses attached to submerged sticks and twigs; a single mass may contain 200 or more eggs. Each egg is enclosed by a membrane, and the entire mass is surrounded by a protective, gelatinous covering. A unicellular alga invades the inner capsules, soon imparting a vivid green color to the whole. In a case of true mutualism, the algae take in the carbon dioxide and nitrogenous wastes of the embryo and u e them in growth and photosynthesis, generating oxygen much needed for embryonic development.
The eggs hatch in one to two months, depending on ambient temperature, and the larval stage lasts two to four months. By late summer the young are fully transformed, ready to leave the ponds and follow the migration trails upslope. They hibernate the winter away, to return in the spring (and each subsequent spring) along the very same route.
There's a major catch to this tale of amphibian reproductive bliss, however. To get from their winter homes to the breeding ponds and back, spotted salamanders must twice cross South Lakeshore Drive-a veritable asphalt death strip. Determinedly following their time-honored paths and oblivious to the danger bearing down upon them, many individuals just don't make it.
But the ones that survive can easily answer the proverbial question: Why does the salamander cross the road? It's the only way to get to the dance.