Vernal pool habitat is a small, but vital part of the refuge. The refuge has 700 acres of vernal pool habitat. Vernal pools are short-lived, seasonal wetlands. Several species, such as endangered vernal pool tadpole shrimp and Contra Costa goldfields are found only in this type of wetland. Resident wildlife are well adapted to the alternating wet and dry periods, with most animals and plants taking advantage of winter and spring rains to reproduce. As the pools dry in the spring, yellow goldfields and purple downingia rim the pools with brilliant color. Some animals, such as fairy shrimp and other invertebrates remain as dormant eggs throughout the long, dry summers. Adult amphibians such as the California tiger salamander migrate to vernal pools to breed and juvenile salamanders leave the vernal pools as they dry during late spring and early summer.