Amphibians
Tiger Salamander
Ambystoma tigrinum · also called eastern tiger salamander
The tiger salamander is a big, blotchy, secretive amphibian — one of the largest salamanders that lives on land, and a close relative of the famous axolotl. Most people who share the landscape with it never see one, because it spends almost its entire life underground.
Overview
Tiger salamanders are found across a huge swath of North America, from the eastern United States and southern Canada down into Mexico, in grassland, prairie, farmland, open woodland, and semi-desert. The one firm requirement is soft, diggable soil near a fishless pond for breeding. They are among the most widely distributed salamanders on the continent, and several regional subspecies exist.
A life below ground
Adult tiger salamanders are fossorial. They dig burrows with their heads and forelimbs, or take over rodent tunnels, and stay in them through heat, cold, and drought, coming to the surface only on wet nights to hunt worms, insects, slugs, and small vertebrates. This underground life is why a common, large animal can be so rarely encountered.
The axolotl connection
Tiger salamanders and axolotls are close cousins, and tiger salamanders can do something their gilled relative does permanently: stay a larva. In cold or permanently watered sites, some tiger salamanders become neotenic, keeping their external gills and finned tail and breeding without ever transforming into the land form. The same population can produce both metamorphosed adults and gilled “water dogs” depending on conditions.
Cannibal morphs and flexible development
Tiger salamander larvae are strikingly plastic. In a crowded, food-poor pond, some develop into a cannibal morph with a broad head and large teeth and prey on other larvae, including siblings. This is a conditional strategy that helps some individuals reach the size needed to metamorphose before the water disappears.
Reproduction
On the first warm rains of late winter or spring, adults migrate to breeding ponds, sometimes in large numbers. Males deposit spermatophores; females pick them up and attach clusters of eggs to submerged vegetation. The larvae are voracious predators of pond invertebrates and tadpoles, and — where they metamorphose — leave the water and go underground within a few months.
Status
The tiger salamander is Least Concern and broadly secure, but it faces the same pressures as other pond-breeding amphibians: loss of breeding wetlands and of the surrounding land the adults burrow in, road mortality on migration nights, introduced fish that eat the larvae, and disease — ranavirus and chytrid fungus — spread partly through the bait and pet trades. A few isolated subspecies, such as the California tiger salamander, are formally listed as threatened or endangered.
Tiger Salamander: common questions
Is the tiger salamander related to the axolotl?
Very closely — they are in the same genus, Ambystoma. The axolotl is essentially a tiger salamander relative that never grows up, staying in its gilled aquatic larval form for life. Tiger salamanders themselves show this "neoteny" in some populations, particularly in cold, high-altitude, or permanent-water sites, where individuals keep their gills and breed while still looking like giant larvae. The two can even be crossbred.
What is a "cannibal morph" salamander?
When tiger salamander larvae are crowded together in a shrinking pond with limited food, some develop into a distinct form with a broader head, a wider mouth, and enlarged teeth, and they begin eating other tiger salamander larvae — often their own pond-mates. It is a flexible developmental response to competition, and it lets at least some individuals get enough food to transform and leave the pond before it dries.
Where do tiger salamanders spend their time?
Underground. Adult tiger salamanders are fossorial, digging their own burrows in loose soil or occupying the tunnels of gophers, ground squirrels, and other animals, sometimes more than half a metre deep. They emerge at night after rain to feed, and in late winter or early spring the whole local population migrates overland to traditional breeding ponds, then returns underground. An adult can go months without surfacing.
Are tiger salamanders good pets?
They are commonly kept and are hardy and long-lived, but they need a large enclosure with deep substrate for burrowing, cool temperatures, and a diet of live invertebrates, and they should not be handled much because their skin absorbs oils and salts. Wild-caught animals are still sold, and moving salamanders and their water between regions has helped spread ranavirus and the chytrid fungus, so captive-bred stock is strongly preferred.