Tiger Salamanders are large burrowing North American amphibians, most active at night. The Latin name is Ambystoma tigrinum; "Ambystoma" means "blunt mouth," and "tigrinum" means "like a tiger." This species is hardy, long-lived, and a very interesting herp to keep.
Tiger Salamanders originate from North America, and range from Florida and northern Mexico to southern Canada and the Rocky Mountains. In some states they have an endangered status, and are protected.
During the rainy season, which corresponds with the breeding season, Tiger Salamanders may be found near ponds, slow streams, marshes, and other small bodies of water. During the rest of the year, they are more secretive, and may be found in prairies, fields, or forests where they burrow under leaf litter or dig underground burrows. They may also live in abandoned burrows made by other animals or invertebrates, such as crayfish. Living underground places them in a group called "mole salamanders." Burrowing allows them to live in cooler, moister environments.
The Tiger Salamander is one of the largest land-dwelling salamanders in the United States. Adults are usually 9-12 inches in length, and some may reach a length of 13-14 inches. It is a stocky animal, with a broad, flat head, a blunt nose, small eyes, and a long, thick tail. There are four unwebbed toes on the front feet and five unwebbed toes on the back feet. As a means of defense, adults secrete a milky substance from glands on their backs and tails, which is toxic if eaten.
Subspecies differences: There are two recognized species: the Tiger Salamander (Ambystoma tigrinum), and the California Tiger Salamander (Ambystoma californiense). Currently, there are multiple (6-8, or more) subspecies of A. tigrinum; however, some researchers suggest that all of the subspecies except the Eastern Tiger Salamander should be a separate species.
Sexual differences: There are no color differences between the sexes, but males tend to be proportionally longer, with a more compressed tail and longer stalkier hind legs than the females. During the breeding season the male may have a swollen vent and the females become heavier.
Color: Tiger Salamanders are highly variable in color. Some have a dark background of black, blue, green or gray, with bars, patches, or spots that are white, yellow, orange, or even black. Others are the reverse, having a lighter background with a darker pattern. The colors vary even among subspecies. The vent is usually yellow or white, flecked with green or black. Colors may change as the salamander ages. There are some albino forms, as well.
Life expectancy: 12-15 years.
Tiger Salamanders tend to be secretive and excitable; however, because they are drawn to food, some of them will learn to take food from your fingers. They are very interesting creatures to observe.
Tiger Salamanders do not like to be handled, so this should be kept to a minimum. When feeding or when cleaning the cage, use slow movements and avoid contact with the animal.
Cages: A vivarium (an environment simulating a species natural environment) setup with both land and water makes the ideal habitat for this species. This environment will help to stabilize the temperature and humidity. The cage or vivarium should be 10-15 gallons (24 x 12 x 12 inches) for a single animal, or 30 gallons (36 x 12 x 12 inches) for a pair. There should be a mesh cover to allow for ventilation.
Cage furnishings: In a vivarium setting, use aquarium gravel of a size larger than the salamander's head to avoid ingestion. If not housed in a vivarium, commercial mulch, dirt, sphagnum moss, or a jungle mix is appropriate. Be sure it is not contaminated with any pesticides or herbicides. This substrate should be kept moist and be several inches thick to allow burrowing. Some type of hiding area should be added in the form of a clay flower pot, hollow log, or stony crevice.
Heat: This species requires cooler temperatures, preferable 68-72ºF during the day, and 50-60ºF at night. Daytime temperatures should not exceed 75ºF.
Light: No additional lighting is needed. The need for adding ultraviolet light is still controversial. Lights may actually raise the temperature above the desired range. Since they are nocturnal, subdued lighting may make them more active.
Water and humidity: Tiger Salamanders require a high relative humidity (amount of water vapor in the air) of at least 70%. The salamander and cage should be misted several times a day. If kept in a vivarium, a pump and filter will help keep the water clean. If not in a vivarium, supply a water source at least one inch deep and 9-10 inches in diameter. If it has a smooth surface, provide a ramp to allow exit from the water. For breeding pairs, provide water at least 6 inches deep, with plants, small rocks, etc. to which the female can attach the eggs.
Tiger Salamanders have a voracious appetite and in the wild feed on insects, earthworms, grubs, small mice, minnows, and even other amphibians, such as frogs. Their diet should consist of earthworms, small snails, wax worms, and crickets or other insects dusted with calcium powder and vitamins. They may also eat some fish foods such as tubifex worms and brine shrimp. Larger specimens may also be fed pinky mice and minnows, however mice are high in fat content and should only be fed occasionally. Tiger Salamanders should be fed every 2-3 days.
Because Tiger Salamanders have such hearty appetites, they produce considerable waste, which will necessitate cleaning the cage frequently.
Tiger Salamanders hibernate during the winter, emerge during the spring rains, and migrate in large numbers to nearby breeding ponds. The males actively compete for females, and after mating, the female lays 1 or more egg masses of 25-50 eggs each (depending upon the subspecies). These are attached to underwater plants, stones, logs, or other debris. The eggs hatch in approximately four weeks into larvae with feathery gills. The larvae feed on aquatic insects, small invertebrates, and fish. The larvae remain in the ponds until late July or early August, and then transform into air breathing sub-adults, 4-5 inches in length. At this time they start to move towards a more terrestrial existence. Some larvae may overwinter (sustain through winter) and not transform into adults until the following spring. Tiger Salamanders reach sexual maturity at 4-5 years of age.
Some larvae may become cannibalistic, and are termed "cannibal morphs." Compared to other larvae, these have larger heads, bigger mouths, and more well-developed teeth. This appears to occur when ponds start to dry up or other food becomes scarce. The cannibal morph larvae eat other tiger salamander larvae, grow faster, and metamorphose into adults earlier. An adult cannibal morph will retain the larger head and bigger mouth of the larvae.
A few populations of Tiger Salamanders in western North America and at high altitudes have a different method of development called "neoteny" or "paedogenesis." In this process, the "normal" larvae do not metamorphose, but continue to breathe through their gills. They become sexually mature and can reproduce although their basic appearance (other than size) does not change. Neotenic Tiger Salamanders can become larger than individuals that metamorphose, reaching total lengths of 15 inches.