The salamander surge in temporary pools

The quiet pools tucked between the oaks and maples at High Banks Preserve hold no fish, no permanent residents. They fill with snowmelt and spring rain, then vanish by midsummer. But right now, in these weeks when the red trillium opens and jack-in-the-pulpit unfurls its hooded flower, these temporary waters pulse with life.

Spotted salamanders (Ambystoma maculatum) emerge from their winter refuges beneath logs and stones, drawn to these ephemeral pools by some combination of temperature, humidity, and ancient memory. They arrive in waves on warm, rainy nights. Males first, then females heavy with eggs. Their blue-black backs marked with two rows of yellow spots, they move with deliberate purpose across the forest floor, navigating by scent and magnetic fields toward water that exists for only a few months each year.

The timing matters. These pools must last long enough for salamander eggs to hatch and larvae to develop, but they cannot support the fish that would devour the next generation. The spotted salamanders have calibrated their breeding to this narrow window. Females deposit their jelly-wrapped egg masses on submerged twigs and stems, sometimes hundreds of eggs in a single gelatinous sphere. Males release sperm packets that females collect, fertilizing the eggs internally. Within days, the adults slip back into the terrestrial world, leaving their offspring to the temporary pond.

What follows transforms the pool into a nursery unlike any other aquatic system. The eggs develop rapidly in the warming water. Larvae hatch with external gills and broad tail fins, feeding first on algae and detritus, then on the abundant invertebrate life that also depends on these seasonal waters. Fairy shrimp, caddisfly larvae, and mosquito larvae create a complex food web in water that will be gone by July. The salamander larvae grow quickly, racing against evaporation. By late summer, those that survive will have absorbed their gills, developed lungs, and emerged onto land as miniature adults.

This pulse of reproduction feeds far beyond the pool itself. The egg masses support symbiotic algae that photosynthesize within the jelly, providing oxygen to developing embryos. Failed eggs and excess larvae become food for other pool inhabitants. Even the adults contribute: their skin secretions add nitrogen to nutrient-poor temporary waters. When the pools dry, this concentrated organic matter enters the soil, enriching the forest floor where eastern teaberry (Gaultheria procumbens) and partridgeberry (Mitchella repens) spread their evergreen mats between the trees.

The whole system depends on this synchrony between salamander breeding and pool persistence. Climate change shifts the timing of snowmelt and spring rains. Development fragments the forest corridors that salamanders follow to reach their ancestral pools. Yet here at High Banks, the ancient rhythm continues. On the next warm night after rain, if you walk quietly through the woods with a flashlight, you might catch the slow procession: spotted salamanders crossing fallen leaves and moss, following paths worn by countless generations toward water that appears and disappears with the seasons.

Listen for the gentle plop of a salamander entering the pool, the soft ripples spreading outward in the darkness.