By Caitlin Bell
During rainy Northern California winters, you may notice water pooling in low-lying pastures. These aren’t your standard mud puddles, but incredibly important and fragile ecosystems that support a variety of species of wildlife. These marshy areas and temporary ponds, called vernal pools, are home to the endangered California Tiger Salamander.
The tiger salamander is native only to California, and can be found from Sonoma County to Santa Barbara. This 8-inch-long stocky salamander is glossy black with yellow spots or stripes, large black eyes, and a wide smiling mouth. During the summer, adult salamanders hide in empty squirrel or gopher burrows in upland areas to avoid the drying sun. But in late fall, they undertake a long and dangerous journey through cow pastures and fields, across roads and through ditches, to reach low-lying areas that have filled with water.
Tiger salamanders need water to reproduce. Almost all amphibians experience a multi-stage life cycle that begins with an adult laying her sticky mass of eggs in a body of water. Some tropical frogs lay their eggs in the tiny reservoirs of water found in the center of bromeliads. In California, the tiger salamander is drawn to vernal pools to lay its eggs. Females can lay up to 1,300 eggs, which she deposits in her wet nursery. Both male and female salamanders then return to higher, drier areas to sleep away the next nine months.
After almost two weeks, the young salamanders emerge from their eggs as tadpoles and begin to hunt their dinner– aquatic insects, mosquitoes, small crustaceans, and algae. The tadpoles are entirely aquatic and breathe using gills, and are thus restricted to the vernal pool boundaries until they undergo metamorphosis in late summer. Once they have assumed an adult body form, the young salamanders will leave the vernal pool and seek out a safe burrow to inhabit until they reach breeding age at four to six years old.
California tiger salamanders are listed as endangered in Sonoma and Santa Barbara counties, and are rare throughout their range. The population of these salamanders is declining mainly because of habitat loss. Vernal pools are fragile and complex ecosystems that are characterized by the complete evaporation of water in the summer, which ensures that no fish can survive in the pools to eat the tadpoles. Much of California’s open space has been converted to agricultural or urban areas, and vernal pools are becoming more and more scarce. In addition, these salamanders reach sexual maturity extremely late for an amphibian. Adults must survive four to six years before they can even begin to breed, and females will wait until water levels are adequate before laying eggs. Some females will breed only once in their lifetime.
The next time you drive by a pasture or field and notice a few puddles, think about the thousands of baby salamanders that may inhabit that ephemeral pool. With increased conservation measures, hopefully California’s special tiger salamander population will not be as short-lived as the pools they call home.
Photo credits: Gary Nafis; Bruce Delgado, U.S. Bureau of Land Management
