One of the western hemisphere's most endangered amphibians, the Santa Cruz Long-Toed Salamander (Ambystoma macrodactylum croceum) is endemic to a small section of coastal California not far southeast of the city of Santa Cruz. Only 23 populations of the salamander are known to exist.
The salamander forms a unique lineage as it diverged long ago from its closest relatives in the Sierra Nevadas and Pacific Northwest, likely due to increased precipitation as the glaciers melted, which caused the growth of coastal redwoods, a tree with which the Santa Cruz Long-Toed Salamander does not generally coexist. The salamanders breed in the late fall and winter when the rains come. They begin their life as embryos in ponds and spend about a month in that embryonic state. They then remain in the ponds in their larval state through the spring, and emerge from their pond before the pond dries in late May or June. Only about 5% of larvae survive to metamorphosis. Some will be eaten by fish, birds or diving beetles. Others may not finish the race to metamorphose before their pond dries. The larvae are easily distinguished from juveniles by their external gills.
SCLTS Photo: Bree Candiloro
The salamanders generally prefer ephemeral ponds, as the regular drying results in fewer predators. However, such ponds also bring with them the chance of drying before the larvae are able to metamorphose -- a certain death. So the salamander maximizes the long-term survival of its species by its ability to also breed in permanent ponds. Unfortunately, many of California's permanent ponds harbor a trematode parasite (Riberoia) that burrows into the salamander's developing hindlimbs and causes extra limbs. The incidence of limb deformities in a wide range of amphibians throughout the United States and Canada has apparently increased in recent decades, likely due to changes in the pond water's composition. As a double blow, agricultural runoff is favorable for the parasite, and pesticides like Atrazine decrease the amphibians' immune defenses. Generally only the larvae are found with deformities. Few adults are found because deformed individuals seldom survive to adulthood, due to their increased probability of being eaten.
Larvae that survive to metamorphosis emerge from the pond in early summer and many remain as juveniles living in cracks in the earth or root hollows near the ponds edge. When the winter rains arrive, they disperse from the pond area in search of a suitable upland habitat such as willow or oak woodland. They may spend several years feeding and growing in the uplands, finally returning as adults one cool and rainy winter's night to a pond to find their mate and perpetuate the species.
The primary threat to the species is the urbanization that surrounds and encroaches on its habitat. The Ellicott Slough Amphibian Reserve -- a US Fish & Wildlife Reserve that was created to protect the salamanders -- is overwhelmingly surrounded by unsuitable, barren farmland that receives heavy pesticide loads. The roads that run through the area can serve as death traps for dispersing salamanders on rainy nights.
"I am also working on the long-toed salamander; as fog disappears it will vanish. This is a certainty. It relies on summer fog to come out and forage at night even in summer. I am instrumenting the area with fog collectors to figure out how much fog there is, whether it is decreasing (a paper by a colleague Todd Dawson suggests this might be so) Thus, this is huge priority for me. I am also working with climate scientists to predict changes in fog into the future."
--Dr. Barry Sinervo; Professor of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA
Purchasing and protecting the land that surrounds the salamanders' current breeding habitat is the most important step to protect the salamanders. As the land the salamanders utilize is near the ocean and very expensive, we must also educate local citizens so that they care enough about the salamanders to contribute financially. Please read our proposal to begin this important work and contact us if you would like to help.