This salamander is sexually dimorphic. Both male and female have black dorsal ground coloring; the bands on the female are gray or silver, and those on the male are white. the sides and the venter are black as well. They are generally short-tailed, stocky and broad-headed (Bartlett & Bartlett 1999).

A. opacum is the most strongly dimorphic of the ambystomatids. They are capable of burrowing, but they rather remain closer to the surface except for seasons of extended drought (Bartlett & Bartlett 1999).

Ambystoma opacum, the marbled salamander is found throughout most of the eastern United States, from Massachusetts west to central Illinois, southeastern Missouri and Oklahoma and eastern Texas, south to the Gulf of Mexico and the Carolina coast. It is absent from peninsular Florida. Disjunct populations are found in eastern Missouri, central Illinois, in northwest Ohio/northeast Indiana, and along the southern edges of Lake Michigan and Lake Erie.

Biogeographic Regions: nearctic (Native )

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Range extends from southern New Hampshire southward to northern Florida, west through southeastern New York to the southern Lake Michigan region, and south to eastern Oklahoma, eastern Texas, and the Gulf Coast. The species is absent from most of the Appalachian Mountains.

The general distribution of the marbeled salamander spans from southern New Hampshire and central Massachusetts, central Pennsylvania west to south Illinois, south Missouri and east Texas, south to north Florida.

A. opacum inhabits sandy and gravelly areas of mixed deciduous woodlands (especially oak-maple and oak-hickory).

Ambystoma opacum is one of the smaller species in the Ambystomatidae family. It attains an adult length of approximately 9-10.7 cm (Conant and Collins 1998). It is sometimes called the banded salamander, because of its white or light gray crossbands across the head, back, and tail. Considered sexually dimorphic, males are smaller than females, and have silvery white crossbands. During the breeding season, the crossbands become very white and glands around the male's cloaca become swollen. Females are larger, and have silvery gray crossbands.

Range length: 9 to 10.7 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous

Sexual Dimorphism: female larger; sexes colored or patterned differently

Length: 13 cm

• Terrestrial
• Freshwater

Adult marbled salamanders live in damp woodlands, often close to ponds or streams. These salamanders are occasionally can be found around dry hillsides, but never far from a moist environment.

Unlike most other mole salamanders, this species does not breed in water. Adult marbled salamanders breed only in dried up pools, ponds, and ditches, and females lay their eggs under the leaves there. The eggs hatch after the ponds refill.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest

Aquatic Biomes: temporary pools

Comments: Marbled salamanders live in various wooded habitats, near swamps or vernal pools. They are more tolerant of dry habitats than are most salamanders and can be found on rocky bluffs and slopes and wooded sand dunes. Adults are entirely terrestrial and spend most of their time under surface objects or underground. Eggs are laid in forest depressions such as vernal pool basins and sometimes at the edges of permanent ponds, swamps, and slow-moving streams, in sites that lack standing water in late summer or early fall but are inundated by fall rains and generally hold standing water through winter and into at least early summer of the next year. Oviposition sites typically are in mineral soil beneath protective cover of leaf litter, logs, detritus, or rocks.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Adults migrate seasonally between upland nonbreeding habitat and breeding sites. Migration distances generally are less than a few hundred meters. Individuals may migrate a short distance from a pool immediately after breeding, then continue migration after a period of winter inactivity.

Even with its small size, an adult Ambystoma opacum is a voracious, carnivorous predator, consuming large amounts of food. Small worms, insects, slugs, and even snails, make up its diet. Attracted to movement as well as odor, this species will not eat dead prey.

Marbled salamander larvae are also active predators, and may be the dominant predators in their temporary ponds. They eat zooplankton (mainly copepods and cladocerans) when they first hatch, but add other prey to their diet as they grow, including larger crustaceans (isopods, fairy shrimp), aquatic insects, snails, oligochaete worms, and the larvae of amphibians, sometimes even other marbled salamanders. In woodland ponds larger larvae sometimes feed heavily on caterpillars that fall into the water.

Animal Foods: amphibians; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms; aquatic or marine worms; aquatic crustaceans; zooplankton

Primary Diet: carnivore (Eats non-insect arthropods)

Comments: Adults eat virtually any small terrestrial invertebrate that is slow enough to be captured. Larvae eat aquatic invertebrates and amphibian larvae.

Marbled salamanders are preyed upon by various woodland predators (snakes, owls, raccoons, skunks, shrews, weasels).

Poison glands located on the tail provide a degree of protection.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: Many and/or large occurrences exist throughout most of the range.

100,000 to >1,000,000 individuals

Comments: Total adult population size is unknown but certainly exceeds 100,000.

Comments: Inactive most of winter. Young larvae diurnal, older larvae nocturnal. Adults most active during rains at night during breeding period.

Average lifespan

Status: captivity: 3.5 years.

Average lifespan

Status: captivity: 4.0 years.

Unlike most others in this family, Ambystoma opacum has a very unusual reproductive strategy. Instead of breeding ponds or other permanent water sources, in spring months, the marbled salamander is a fall breeder, and breeds entirely on land.

After finding his mate, the male will court with the female, often moving in a circular fashion with her. The male will then proceed to undulate his tail, and raise his body. Following this, the male will deposit a spermatophore onto the ground. If interested, the female will then proceed to pick it up with her cloacal lips (Petranka 1998). After mating the female will venture off and select a small depression in the ground. This depression is usually a reduced pond, or dried bed of a ditch or temporary pond (Petranka 1998). The female will lay a clutch of between fifty and one hundred eggs. Once deposited the female will remain with them to keep them moist, until nests are flooded. As soon as the autumn rains come the eggs will hatch in the depression they were originally laid in. If rain never comes the eggs will remain dormant through the winter if temperatures do not fall too low, then hatch the following spring (Flank 1999).

Once hatched the gray colored larvae (1 cm) grow extremely quickly, eating primarily macrozooplankton. Large larvae, however, will eat amphibian larvae and eggs (Petranka 1998). The timing on metamorphosis depends on geographic location. Those that are found in the South can go through metamorphosis in as little as two months. Those in the northern climates generally take between eight to nine months (Petranka 1998). Young juveniles are approximately 5 cm, and attain sexual maturity in about 15 months, after metamorphosis (Flank 1999).

Breeding interval: Marbled salamanders breed once per year.

Breeding season: Breeding starts in the late summer in the northern part of the range, and extends into November in the southern part.

Range number of offspring: 50 to 100.

Range age at sexual or reproductive maturity (male): 17 to 26 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous

Average age at sexual or reproductive maturity (female)

Sex: female: 1460 days.

Mating and egg deposition occur in late summer or early fall (August-November; earlier in the north than in the south). Mating often occurs before the female arrives at pond-basin nesting areas (Krenz and Scott, 1994, Herpetologica 50:46-50). Females deposit single clutches of up to about 250 eggs, which are attended by the female until the nest is flooded (female commonly deserts nest if disturbed before flooding). Larvae hatch in fall (usually) or as late as spring, depending on when rains flood the nest. Larvae metamorphose in spring or early summer and move into upland habitats. Most first-time breeders are at least a few years old. Maximum life-span is at least 11-12 years.

In South Carolina, reproductive success varied among different years; little or no recruitment occurred during drought periods (Pechmann et al. 1991). Food limitation may reduce individual female reproductive output (Scott and Fore 1995, Herpetologica 51:462-471).

This species is listed as threatened by the Michigan Department of Natural Resources (DNR). In other areas it is not considered threatened and can be locally common.

Declining populations in the Great Lakes region can be attributed to both declining habitat but more so the effects of widespread temperature cooling after a warmer postglacial climate brought them into the area.

US Federal List: no special status

CITES: no special status

State of Michigan List: threatened

IUCN Red List of Threatened Species: least concern

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Large extent of occurrence in eastern United States; high abundance, many stable populations throughout the range.

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Many local breeding sites have been eliminated by conversion of habitat to intensive human uses, and such loses are ongoing (Petranka 1998). However, a large number of stable populations exist, the overall rate of decline probably is less than 10 percent over 10 years or three generations.

Global Long Term Trend: Increase of 10-25% to decline of 50%

A. opacum start to migrate to their breeding areas in the fall (generally in September). An average of 100 egss are laid in shallow depressions under surface material. They are then washed into the water to hatch. The eggs hatch at different times under different conditions. If the eggs are submerged, they will hatch in the fall or early winter. If there is no rain, the eggs will hatch in the spring. The larval period is affected by differing conditions as well. If the eggs hatch in the spring, their metamorphosis will be slower, transforming into their terrestrial form in late May to June. If there is a higher temperature and an abundance of food, metamorphosis will be hastened (DeGraaf & Rudis 1983).

Diet consists of eat arthropods, worms and mollusks. Larvae eat insects, crustaceans, and other small invertebrates. They can also be cannibalistic (DeGraaf & Rudis).

Comments: Threats to local populations likely include intensive timber harvesting practices that reduce canopy closure, understory vegetation, uncompacted forest litter, or coarse woody debris (moderately to well-decayed) in areas surrounding breeding sites (deMaynadier and Hunter 1999). Breeding sites are vulnerable to destruction and degradation through draining and filling, and many are being isolated by habitat fragmentation, which could eventually result in deleterious levels of inbreeding and reduced chances of reestablishment of locally extripated populations. Thousands of local populations already have been eliminated by habitat loss, and more will be lost in the future (Petranka 1998).

Global Protection: Very many (>40) occurrences appropriately protected and managed

Marbled salamanders have no economic importance.

Comments: See Kraus (1988), Shaffer et al. (1991), and Jones et al. (1993) for phylogenetic analyses of North American Ambystoma.