Wednesday, March 17, 2010

IT’S SALAMANDER SEASON!



Spring has sprung, or at least it’s about to spring, and it’s the time of year when amphibian activity becomes most noticeable.

Washington supports populations of 14 species of salamanders and 11 frogs. Amphibians like wet climates, and we’ve got that. Salamanders are diverse in temperate latitudes, frogs a bit less so, but as usual, the tropics are the home of the greatest diversity (compare Costa Rica’s 43 salamanders and 133 frogs!).

Our rainy winter provides the water to allow frog and salamander breeding, and as soon as it warms up enough in spring, off they go. This happens in late February or March for a variety of species.


Northwestern Salamanders (Ambystoma gracile) live underground for much of the year but come to the surface to feed in spring and during fall rains. They are rarely seen but could be observable at night at breeding ponds, when the adults come to the water to breed. Males court females, then when both are ready, the male deposits a spermatophore which the female picks up in her cloaca. The sperms within fertilize her eggs as she lays a big clutch of around 100 eggs in a jelly envelope the size of an orange, usually wrapped around some underwater object. The larvae stay in the water for a year or more, then undergo metamorphosis to the terrestrial stage and breed in the next spring.

Meanwhile, Long-toed Salamanders (Ambystoma macrodactylum) are migrating to other ponds, often smaller ones. This species is more common and wide-ranging, occurring in drier parts of the Northwest and well up in the mountains as well as the wet western lowlands. Breeding occurs in the spring, but females lay much smaller egg masses, averaging only a dozen or so eggs. Being a smaller species, metamorphosis and maturation are quicker than in the Northwestern.

Rough-skinned Newts (Taricha granulosa) are also stirring from their winter retreats and heading for the water. Like the others, they migrate mostly on rainy evenings to their breeding lakes. Courtship is prolonged, even lasting a day or more, but usually ending with spermatophore pickup, fertilization, and egg-laying. Eggs are laid singly in aquatic vegetation. The larvae metamorphose and leave the water in fall and disperse away from the water, to which they return after 4 or 5 years. In this species, many breeding adults remain aquatic through the summer, developing smoother skin and tail crests that aid in swimming.

By contrast, two of the common salamanders of the Northwest are terrestrial, with no aquatic stage. They are lungless salamanders, breathing through their skin! Western Red-backed Salamander (Plethodon vehiculum) and Ensatina (Ensatina eschscholtzii) live in forests, where they can be found in spring by turning over logs (be sure to replace divots!). They breed during winter, laying their 10 eggs in a cluster in such sheltered places, and the female guards them from invertebrate predators until they hatch.

Most of the other salamanders of the Pacific Northwest are locally distributed and uncommon, but they are worthy of attention by any naturalist fascinated by creepy-crawly critters. There is a good reference book: Amphibians of the Pacific Northwest, by L. L. C. Jones, W. P. Leonard, and D. H. Olson, eds., Seattle Audubon Society, 2006.

Dennis Paulson

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