Amphibians
California Tiger Salamander
Ambystoma californiense · also called CTS
The California tiger salamander is a grassland animal that is almost never seen on the grass. It spends ten or eleven months of the year underground, borrowing a rodent’s burrow, and surfaces only on the wettest winter nights to make a dash for a temporary pool.
Overview
Ambystoma californiense is endemic to California, in the grasslands and oak savanna around the Central Valley and the Coast Ranges. Adults are stout, glossy black with bold cream bars, about 18–22 cm long. It is a mole salamander, built for a life spent hidden.
Burrow and pool
For most of the year it lives in a burrow dug by a ground squirrel or pocket gopher, staying cool and moist. Winter rain draws it out to breed in vernal pools and stock ponds — fishless, temporary water where the large larvae have a few months to transform before it dries.
The hybrid problem
Barred tiger salamanders, imported decades ago as fishing bait, have interbred with the native species. The hybrids are bigger and more aggressive, and they are replacing pure California tiger salamanders across much of the Bay Area and Salinas Valley — a genetic invasion that habitat protection cannot undo.
Status
Vulnerable, and federally listed as Threatened or Endangered depending on the population, after the loss of most of its grassland and vernal-pool habitat.
California Tiger Salamander: common questions
Why does the California tiger salamander live in ground squirrel burrows?
Because it needs a cool, humid refuge for most of the year and it cannot dig one for itself. The grasslands it lives in bake dry and hot for the long California summer, lethal conditions for a moist-skinned amphibian on the surface. Burrows made by California ground squirrels and Botta's pocket gophers stay cool and damp a metre or more down, and the salamander simply moves in, sometimes alongside the rodent that dug it. This makes the salamander completely dependent on healthy rodent populations; where ground squirrels have been poisoned or ploughed out, the salamanders disappear even if the ponds are still there.
What is the problem with the hybrids?
Starting in the 1940s and 1950s, barred tiger salamanders from Texas and the Great Plains were imported into central California and sold as live fishing bait; released or escaped animals established in ponds within the native salamander's range. The two are close enough to interbreed, and they have, extensively, in parts of the Salinas Valley and the Bay Area. The hybrids are not a minor curiosity; they grow larger, their larvae are better at surviving in permanent water, and they outcompete and displace pure native salamanders. Because the invasive genes are already spread through wild populations, habitat protection alone cannot fix it, and managers are left trying to keep the hybrid zone from expanding.
Is it the same as the tiger salamander found across the rest of the US?
It is a close relative but a distinct species. The widespread eastern tiger salamander, Ambystoma tigrinum, and the western barred tiger salamander, Ambystoma mavortium, range across much of North America and are not of conservation concern. The California tiger salamander, Ambystoma californiense, was recognised as a full species separate from those in the 1990s. It is restricted entirely to California, it is more specialised on grassland and vernal pools, and it is the one that is threatened, both directly and through hybridisation with its introduced relatives.
Can you keep a California tiger salamander?
No. It is illegal to collect, keep, harm, or move a California tiger salamander without a permit, because it is protected under both federal and California endangered species law throughout its range. Even handling one found crossing a road during the breeding migration is discouraged beyond gently moving it off the pavement in the direction it was heading. Anyone who wants a tiger salamander as a pet should look for a captive-bred eastern or barred tiger salamander from a reputable source, never a wild-caught animal and never this species.