Spotted salamanders are found in eastern North America. Their range extends from Nova Scotia and the Gaspé Peninsula west to the northern shore of Lake Superior, and south to southern Georgia and eastern Texas. The spotted salamander is absent from most of southern New Jersey, the Prairie Peninsula in Illinois, eastern North Carolina, and the Delmarva Peninsula.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000 to >2,500,000 square km (about 80,000 to >1,000,000 square miles)) Range extends throughout most of the eastern United States (except Florida) and adjacent southern Canada; west to eastern Iowa and eastern Texas (Conant and Collins 1991).

Adult spotted salamanders are 15-25 cm in total length, and females tend to be larger than males. Compared to other salamanders, the body is stout with a broadly rounded snout. The sides of the head are often swollen at the back of the jaw. The legs are large and strong with four to five toes.

The background color of metamorphosed spotted salamanders can be black, dark brown, or dark grey, while the bottom half and under-surface of the limbs are a pale slate gray. On either side of the mid-dorsal line of the body are large, round, yellow or orange spots. The spots may vary in number from 24 to 45, and they are arranged in two irregular rows running along the sides from the head to the tail. Unspotted individuals do occur but are rare.

Spotted salamanders have poison glands in their skin, mostly on their backs and tails. These glands release a sticky white toxic liquid when the animal is threatened.

When they hatch, the larvae of this species are 12-17 mm long. Their dorsal surface is dull olive green, and they remain a dull greenish color until they transform into the adult form. The underside of larvae is nearly white, and tail is finely stippled or mottled, with dark pigment near the tip.

Range length: 150 to 250 mm.

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

Average mass: 12.84 g.

Average basal metabolic rate: 0.005 W.

Length: 25 cm

• Terrestrial
• Freshwater

Adult spotted salamanders are most abundant in deciduous bottomland forests along rivers, but can be found in upland mixed or coniferous forests if the climate is sufficiently damp and there are ponds suitable for breeding. Adults are rarely seen because they spend most of their time hiding in leaf litter, under fallen wood, or in tunnels below ground.

Like most Ambystoma salamanders, spotted salamanders lay their eggs in fresh water, but only in ponds and pools that lack fish. They often use temporary vernal pools.

Habitat Regions: temperate ; terrestrial ; freshwater

Terrestrial Biomes: forest

Aquatic Biomes: lakes and ponds; temporary pools

Comments: Spotted salamanders inhabit hardwood and mixed forests, in the vicinity of swamps and vernal pools. They are usually underground or under soil surface objects except during the breeding period. Logs, stumps, and mammal burrows provide important cover (Faccio 2003). In New York, distribution apparently is influenced by soil pH (Wyman 1988).

Eggs usually are attached to submerged stems or other objects in vernal pools and semipermanent or permanent ponds in or adjacent to forest. In many areas, the species breeds mainly in ponds inaccessible to predatory fishes; however on the Atlantic Coastal Plain of the southeastern United States, spotted salamanders breed in sloughs or backwater lowland areas along streams that frequently contain or are easily colonized by predatory fishes that opportunistically feed on amphibian larvae (Semlitsch 1988). Eggs may be laid in ponds when they are ice-covered if salamanders already are present in the pond (States et al. 1988).

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.

Migrations between nonbreeding and breeding habitats extend up to several hundred meters. Mean distance between breeding site and summer/winter habitat was 192 m, 150 m, 118 m, and 64 m in four studies; see Kleeberger and Werner (1983) and Madison (1997). In Vermont, 5 radio-tagged individuals moved 52-219 m (mean 137 m) from the edge of their breeding pool (Faccio 2003).

Individuals tend to enter and exit breeding ponds along the same route in successive years (Phillips and Sexton 1989).

Salamander larvae are aggressive predators. They are generalists, eating whatever small animals they can catch. When they first hatch they feed mainly on small insects, and branchiopod crustaceans like Daphnia and fairy shrimp. As they get larger they take larger prey, including isopods, amphipods, larger insects, frog tadpoles, and other salamander larvae. In times of overcrowding, usually when the vernal pools start to dry up, spotted salamander larvae may become cannibalistic and attack members of their own species.

The adult spotted salamander uses its sticky tongue to catch food. Their diet consists mainly of forest floor invertebrates, including earthworms, snails and slugs, millipedes, centipedes, spiders, and a wide variety of insects. They sometimes also eat smaller salamanders, such as the red-backed salamander, Plethodon cinereus.

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

Primary Diet: carnivore (Insectivore , Eats non-insect arthropods); planktivore

Comments: Larvae eat mostly small aquatic invertebrates (especially copepods and cladoderans, also chaoborids); sometimes also amphibian larvae when available. Adults eat various terrestrial invertebrates (DeGraaf and Rudis 1983).

Spotted salamanders can be important to the community of species that live and breed in vernal pools, affecting the abundance and diversity of other species in the pools, especially other amphibians. Gray treefrogs (Hyla chrysoscelis and Hyla versicolor) avoid breeding in ponds with spotted salamanders in them, and depending on the timing and size of the other species present, spotted salamanders may reduce the population of other Ambystoma species in their pools.

Mutualist Species:

• a unicellular green alga Oophila amblystomatis 

Spotted salamander defense begins immediately following laying of eggs. The eggs are laid in masses that are covered in a thick, firm, jelly, overcoat to protect against some predators (e.g. leeches and sunfish) and from dehydration, should the egg mass be temporarily exposed by sinking water levels. There is a particular species of unicellular green alga (Oophila ambystomatis) that grows on and in the jelly. The algae provides extra oxygen to the developing embryos, and may help camouflage the egg mass as well.

Despite this protection, a number of predators eat spotted salamander eggs: adult newts, wood frog tadpoles, crayfish and some species of caddisfly (especially Ptilostomis postica and Banksiola dossuaria) and midges in the genus (Parachironomus). These predators are so effective that in some years up to 90% of eggs may be killed before they hatch.

Spotted salamander larvae are also heavily preyed upon. Hatchlings are eaten by those aquatic creatures previously mentioned and also various aquatic insects, fish, wading birds, other Ambystoma species, and snakes. Hatchlings raised in laboratories often die from protozoan infections as well.

Adult spotted salamanders are preyed upon by larger animals, including skunks, raccoons, turtles, and snakes, especially garter snakes (genus Thamnophis). Like many other salamanders, adult spotted salamanders secrete a milky toxin from glands on the back and tail for defense against predation. The bright spotting on these salamanders functions as a warning to predators of their toxic defense.

Adult spotted salamanders respond to attack by arching the body and sometimes butting with the head or lashing with the tail, probably to expose the predator to as much poison as possible. They sometimes bite, and individuals of all sizes may also make sounds when attacked.

Known Predators:

• raccoons
• turtles
• snakes
• sunfish
• birds
• aquatic frogs
• newts
• a caddisfly (Ptilostomis postica)
• a caddisfly (Banksiola dossuaria)
• midges in the genus (Parachironomus)

Anti-predator Adaptations: aposematic

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

Estimated Number of Occurrences: > 300

Comments: Throughout the range, occurrences are many and/or large.

100,000 to >1,000,000 individuals

Comments: Total adult population size is unknown but surely is greater than 100,000 and may exceed 1,000,000.

Larvae may be preyed on by larval A. opacum where the two occur together. Predation on larvae by fishes may prohibit successful reproduction (Ireland 1989). In a Massachusetts pond, survival to metamorphosis was 3.1% for 10,000+ embryos in a year when pond did not dry; up to 13% survival recorded in other studies (see States et al. 1988). In West Virginia, larvae of the caddisfly Banksiola dossuaria preyed on embryos (Stout et al. 1992). In Pennsylvania, larvae of the caddisfly Ptilostomis postica sometimes preyed heavily on embryos (Rowe et al. 1994).

See Semlitsch (1988) for information on factors affecting ecological distribution in southeastern U.S.

The egg masses of spotted salamanders sometimes contain green algae that use the carbon dioxide produced by the embryos and in turn produce oxygen that the salamander embryos can use.

These salamanders locate prey by smell and sight. Their vision is probably best for detecting motion in low light. Sense of smell is important in orienting spotted salamanders to their burrows and to their home pond, as are visual and tactile information. It is believed that home pond odors are preferred compared with foreign pond odors.

During courtship, males nudge and rub females, probably communicating with both touch and smell. Females are attracted by the chemical scents given off by males in the water.

Communication Channels: visual ; tactile ; acoustic ; chemical

Other Communication Modes: pheromones

Perception Channels: visual ; tactile ; acoustic ; chemical

Comments: Adults most active during rains at night during breeding period.

Spotted salamanders go through several stages over their lifetime. Female salamanders lay their eggs under water, and the larvae that hatch from the eggs are aquatic, with gills for taking oxygen from the water, weak legs and a broad tail for swimming. Larvae feed and grow in the water, and then metamorphose into an juvenile form with lungs and strong legs. Juveniles live on land, and after 2-3 years they mature into adults that can reproduce.

This species has relatively long incubation time in comparison to other salamanders. It takes 4-7 weeks for the eggs to hatch, depending both the temperature of the water they are in, and whether the eggs are laid in shady or sunny areas.

Spotted salamander larvae are 12-13 mm long when they hatch, with feathery gills and only their front legs present

Larvae grow quickly and transform within 2 to 4 months after hatching. Average size after metamorphosis ranges between 27 and 60 mm, depending on the conditions in the pond. The yellow and orange spots are usually acquired within a week following transformation.

Development - Life Cycle: metamorphosis

Most spotted salamanders (more than 90%) die before they transform and leave their pond, either because their pond dries up, or they are killed by predators or disease. If they do survive and make it out of the pond, they typically live about 20 years in the wild, though some have been reported as old as 30. Their chance of survival from one year to the next is much much higher after they transform.

Range lifespan

Status: wild: 30 (high) years.

Typical lifespan

Status: wild: 20 (high) years.

Average lifespan

Status: captivity: 25.0 years.

Spotted salamanders begin migration to breeding ponds at night, during the first rain following the thaw of snow. Males respond more quickly to the rain and move faster than do the females, therefore they arrive to the pool first. They also stay longer in the ponds than females do, probably to increase their chances of fertilizing more eggs each year. The number of males present in the breeding pools is greater than the number of females, so when the females arrive the males swim about vigorously, rubbing and nosing each other. Males produced blobs of sperm called spermatophores (up to 80 per male), and the females take these spermatophores into their bodies to fertilize their eggs. Each male may fertilize several females, and each female may take up spermatophores from several males.

Male spotted salamanders may compete with other males for the chance to fertilize females. They push other males away from females, produce as many spermatophores as they can, and sometimes cover other males' spermatophores with their own.

Mating System: polygynandrous (promiscuous)

It takes several years for spotted salamanders to become reproductively mature, and the time required is strongly affected by the climate where they live. In the warmer parts of their range they may be ready to breed in 2-3 years, but further north they males may take 5 or 6 years and females as many as seven years.

See the Behavior section for more details on breeding behavior.

Females lay compact egg masses that are attached to submerged objects. The egg mass is covered with thick, clear or milky-white jelly. Each female lays approximately 100-300 or more eggs per year, in several separate masses. Reported averages are about 200 eggs per female per year.

Breeding interval: Spotted salamanders breed once yearly

Breeding season: Eggs are laid in winter or early spring, starting in late December in the southern portion of the species' range, and as late as early May in Nova Scotia

Range number of offspring: 100 to 370.

Average number of offspring: 200.

Range time to hatching: 4 to 7 weeks.

Range age at sexual or reproductive maturity (female): 2 to 7 years.

Range age at sexual or reproductive maturity (male): 2 to 6 years.

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

Male spotted salamanders provide no parental care. Females invest nutrients in provisioning their eggs with yolk and supplying them with protective layer of jelly. They also make an effort to lay the eggs in a suitable location, usually on submerged tree branches or aquatic plants. There is no further investment after the eggs are laid.

Parental Investment: pre-fertilization (Provisioning)

Rain and warming temperatures stimulate migrations to breeding ponds in winter or early spring (Grace and Church 2003). Migrations to breeding sites occur in March-April in the northern part of the range, mainly December-February in the south. In eastern Missouri, migration to ponds occurred after the first week of February on all days when mean 3-day temperature was at least 5.5 C and precipitation at least 4 mm (Sexton et al. 1990). After arriving in the breeding pools, females pick up sperm from the spermatophores that males deposit on the pool bottom. Soon thereafter females attach masses of eggs to submerged stems or other submerged objects. Individual females deposit up to 250 eggs (average <100); eggs of an individual females may be laid in one large mass or divided among several masses of about 50-90 eggs. Hundreds of females may deposit eggs in a single pool, and the egg masses of different females often exhibit an aggregated dispersion pattern. Larvae hatch in 1-2 months.In a pond in Ohio, hatching rate over 4 years was 60-72%, and the number of larvae that hatched ranged from 232,000 to 527,000 (Brodman, 1995, J. Herpetol. 29:111-113). Larvae metamorphose in 2-4 months or sometimes overwinter in the pond. In eastern Missouri, metamorphosis occurred mainly by October in some years, in spring after overwintering in other years (Phillips 1992). In Massachusetts, mean time from hatching to exit from pond was 98 days (States et al. 1988). Newly metamorphosed individuals live on land for a few years before returning to water to breed (usually in their natal pool).

In Quebec, most individuals caught in temporary ponds in spring were between 2 and 18 years old; most females were mature by the age 7 years at SVL greater than 78 mm whereas many males reached maturity between the ages of 2 and 6 years at SVL greater than 63 mm (Flageole and Leclair 1992).

Many individuals usually breed in a single pool (e.g., in eastern Massachusetts, 196 males and 132 females entered a pond with a surface area of about 30 square meters; 118 egg masses were found (States et al. 1988). Harris (Copeia 1980:719-722) found 237 egg masses in one pond.

Algae encapsulated in cells of spotted salamander may provide photosynthetic products (oxygen and carbohydrate) by internal symbiosis.

"At a presentation on 28 July at the Ninth International Congress of  Vertebrate Morphology in Punta del Este, Uruguay, Ryan Kerney of Dalhousie University in Halifax, Nova Scotia, Canada, reported that  these algae are, in fact, commonly located inside cells all over the  spotted salamander's body. Moreover, there are signs that intracellular  algae may be directly providing the products of photosynthesis — oxygen  and carbohydrate — to the salamander cells that encapsulate them ... Because vertebrate cells have what is known as an adaptive immune system  — which destroys biological material not considered 'self' — it was  thought to be impossible for a symbiont to live stably inside them. But,  in this case, the salamander cells have either turned their internal  immune system off, or the algae have somehow bypassed it." (Petherick 2010:1)

The spotted salamander is still a fairly common species, but its populations are particular vulnerable because of their dependence on vernal pools for breeding. Acidic precipitation has a negative effect upon their embryos, and habitat destruction is a problem, especially as it isolates populations from each other. The species is rated "of Least Concern" by the IUCN, and is not listed by the U.S. Endangered Species Act, in the CITES appendices, or by the State of Michigan.

The spotted salamander is still a fairly common species, and it is not considered endangered. However, the species depends on vernal pools to survive and reproduce, and this habitat is threatened by acid rain and deforestation. The species is rated "of Least Concern" by the IUCN, and is not listed by the U.S. Endangered Species Act, in the CITES appendices, or by the State of Michigan.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

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: Populations declined in eastern Virginia during the 1980s (Blem and Blem 1991).

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

Breeding typically takes place en masse, where males are often known to congregate earlier at the breeding pond. The sex ratio at the breeding pond is often skewed in favor of males by 1.5-3.5 times more. Husting (1965) had shown a ratio of 4.43 males per female after a 4-year study. Beginning breeding times vary geographically, though generally in the southern portion of the range breeding begins as early as December, and in the more northern portions of the range March-April. Length of the breeding season varies significantly with location and may range from 3 days to over two months. Typically, the more northern populations have two or three highly synchronized breeding bouts, often only lasting 2-3 days (Petranka 1998).

A fairly elaborate courtship may take place at breeding in which the male contacts a female and engages in a nudging ritual. After the male repeatedly encircles the female, he deposits spermatophores on the substrate for the female to pick up with her cloaca. Males will often deposit their spermatophores on top of other males' spermatophores if encountered during the courtship. The female deposits the egg masses within 2-3 days after fertilization, attaching them to submerged vegetation. The embryonic period typically lasts between 4-7 weeks, and larvae metamorphose after 2-4 months. In some cases slow growing larvae may not transform until the following spring or summer, overwintering in the pond. Within a few weeks after metamorphosis, the newly transformed salamanders disperse into the surrounding upland habitat during moist weather. It is not clear how long the juvenile stage lasts, though time to reproductive maturity is believed to be 2-3 years (slightly longer for females), at which time individuals return to the pool to breed (Petranka 1998).

Despite the relative isolation of suitable breeding sites and the high tendency towards site fidelity, migration between ponds does occur. Zamudio and Wieczorek (2007) found that immigration between ponds was common within demes in their Tompkins County, New York study populations. Their data suggested that A. maculatum breeding groups were behaving as metapopulations, such that population clusters were the functional units but with sufficient migration between demes to enable potential rescue and recolonization. High gene flow was also found between A. maculatum breeding ponds in northeastern Ohio, despite landscape fragmentation (Purrenhage et al. 2009).

Spotted salamander egg masses are preyed on by wood frog tadpoles (Rana sylvatica) as the embryos near the end of development; in turn, the frog tadpoles are preyed on by larval salamanders (Petranka et al. 1998).

This salamander is the first vertebrate reported to have photosynthetic symbionts within its cells and tissues, the single-celled alga Oophila amblystomatis. Previously it had been thought that the algae were external to the salamander embryos, but recent work by Ryan Kerney of the University of Dalhousie shows that the algae are actually within the embryonic cells. The symbiosis does not last through development; algal cells are detectable up through larval stage 44, and fewer algal cells are present in later stage larvae (Kerney et al. 2011). Transmission may take place in the salamander oviduct (Kerney et al. 2011). For a commentary on the initial report of this work at the July 2010 Ninth Internal Congress of Vertebrate Morphology (held in Uruguay) and a photo of the algae-harboring embryos, see Petherick (2010) in Nature News.

Comments: Threats to local populations 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). Dispersing juveniles tend to avoid open canopy habitat, so deforestation and fragmentation likely reduce dispersal rates between local populations and could negatively impact population persistence in altered landscapes (Rothermal and Semlitsch 2002). Negative impacts of intensive timber harvesting extend at least 25-35 m into uncut forest (deMaynadier and Hunter 1998).
Many populations are becoming increasing isolated as deforestation and loss of vernal pools reduce gene flow among demes (Petranka 1998). This may result in inbreeding depression and reduce the probability of reestablishment of extirpated populations.
Local populations may be heavily impacted by excessive mortality of adults caused by vehicles on roads near breeding sites. Roads negatively impact salamander abundance in roadside habitat and may serve as partial barriers to movement (deMaynadier and Hunter 2000).
Embryo mortality generally decreases as pH deceases below 6.0, though in some areas successful reproduction has occurred at a relatively low pH (Cook 1983, Blem and Blem 1989). In central Pennsylvania, low pH was associated with deleterious sublethal effects on larvae (Sadinski and Dunson 1992).
High concentrations of various chemical elements, unfavorable temperatures, or low oxygen content may result in reproductive failure; see Blem and Blem (1991) and Albers and Prouty (1987). Deicing salts that contaminate roadside vernal pools result in reduced embryonic survival (Turtle 2000).

Timber harvesting significantly changes the habitat by reducing forest floor litter (decayed woody debris), understory vegetation, and canopy closure in areas surrounding breeding sites (deMaynadier and Hunter 1999). These changes affect not only the immediately impacted forest area but also affect whether habitat is suitable for salamanders in surrounding uncut forest, at least 25-35 m in (deMaynadier and Hunter 1998).

If roads run near breeding sites, salamanders may be crushed by cars. Roads may also serve as a partial barrier to movement, further fragmenting the habitat (deMaynadier and Hunter 2000).

In addition to habitat loss and fragmentation this species (especially at the larval stage) may be sensitive to decreased pH levels in breeding pools due to increased acid deposition from weather patterns or road salting (Turtle 2000; Sadinski and Dunson 1992). Low pH (<6.0) has a deleterious effect on embryo survival, although reproduction can occur in ponds with low pH (Cook 1983; Blem and Blem 1989).

Pesticide contamination of water can significantly impact A. maculatum. Low-level contamination of ponds with pyrethroid insecticides (permethrin and fenvalerate, administered at .01 to 2 ppm, singly or in combination, for 22 or 96 hours) did not kill spotted salamander larvae but was found to affect behavior. Larvae that were prodded responded abnormally by twisting rather than swimming away, suggesting that a single episode of pesticide exposure was enough to render them more vulnerable to predation. Of the five amphibian species tested (four anurans plus A. maculatum), A. maculatum was most susceptible to pesticide effects (Berrill et al. 1993). Mesocosms treated with the insecticide carbaryl (at 3.5 or 7.0 mg/ml) had high mortality of spotted salamander embryos (Boone and James 2003).

It is not known whether chytrid infection leads to mortality in this species, but it can be infected with chytrid; Ouellet et al. (2005) found evidence of Bd infection in 4 of 139 Canadian specimens.

Management Requirements: Needed conservation measures include protection of vernal pools and adjacent wooded areas up to at least 200-250 m from the pools. Also, regulatory agencies should attempt to minimize forest fragmentation. The species could benefit from regulations that minimize acid deposition.

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

There are no known adverse effects of Ambystoma maculatum on humans.

Spotted salamanders may help control insect pest species, including mosquitoes that breed in their ponds.

Comments: "Despite apparent morphological uniformity, genetic discontinuities throughout the range of this species suggest that populations were historically fragmented in at least two refugia in the southern Appalachian Mountains. The ranges of these two highly divergent clades ["coastal" and "interior"] expanded northward, resulting in two widely distributed lineages that are sympatric in regions previously proposed as suture zones for other taxa." (Zamudio and Savage 2003).

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

Allozyme data indicate that the closest relative of A. maculatum is A. gracile (Shaffer et al. 1991), a conclusion that is not supported by any morphological data (Kraus 1988).