Geographic Range: The four-toed salamander, occurs from Nova Scotia to northern Minnesota, and south to the Gulf of Mexico. It has a discontinuous range and occurs only in small isolated populations in the southern and midwestern states. Its range is more continuous in states along the Appalachian Mountain Range, New England and west to northeastern Minnesota.

Habitat: Four-toed salamanders have specialized habitat requirements which require suitable breeding wetlands within or adjacent to mature forests. They prefer mature, mesic forests with dense canopy cover to preserve body moisture, an abundance of downed woody debris for cover and foraging opportunities, and vernal pools, ponds, bogs, shallow marshes, or other fishless bodies of water for nesting and larval success. Wooded wetlands such as seepage swamps or cedar swamps with many moss mats are ideal. Male adults can be located under leaves, bark, and logs in the upland forest, while females are most often found during the breeding season nesting in moss mats which overhang pools of water.

Photo by John White.

Description: The four-toed salamander is a small plethodontid (lungless) salamander only 5 to 10.2 cm (2 to 4 in) in length. It is a rusty brown color or gray-brown color with grayish sides. It is often speckled with black and bluish spots. Unique four-toed hind feet and a constricted ring around the base of its tail easily identify it. They have nasolabial grooves and 13 to 14 coastal grooves. The tail makes up about 57 percent of its total body length.

Female four-toed salamanders have rounded snouts, while sexually active males have more squared (truncated) snouts. Enlarged premaxillary teeth are also evident in sexually active males and can be seen with a closed mouth. The snout-to-vent length (SVL) is approximately 15 percent longer in females than males.

Hatchlings are only 11 to 15 mm total body length. They are usually born with toes or toe buds. The larvae are aquatic and a yellowish brown color. A dorsal fin runs from the length of the tail to near the back of the head. Some hatchlings look more like adults but have shorter tails.

Diet: Few studies have been conducted on the feeding habits of the four-toed salamander, but it is believed their diet consists mainly of insects and their larvae (beetles, flies, ants, bristletails), spiders, mites, worms, and snails.

Reproduction: Mating occurs in the late summer, fall, and possibly into early winter in some places. The male courts the female first by rubbing his nose on the female's nose, then he will circle around her with his tail bend at a sharp right angle. At some point the female straddles the male's tail and presses her snout on the base of his tail. Eventually the male starts moving forward, undulating his tail, and begins depositing spermatophores, while the female follows him at a close distance. The spermatophores are a jelly-like glob that are about 2mm wide at the base and tapers to a thin stalk, which is topped with a yellowish sperm cap. The female picks up the spermatophores and deposits them into her cloaca while pressing her snout against the male's tail. This "straddle walk" lasts for up to 20 minutes.

Eggs Female four-toed salamanders migrate to nesting sites primarily from the last week of March through the second week of April, but may wait until as late as early June. Oviposition occurs from mid to late April in Michigan, but can occur as late as February in southern Alabama. Females seek out moss clumps that are just above a pool of water usually in swamps, bogs, marshes, vernal pools, and slow moving streams. The nesting medium is usually raised clumps of sphagnum moss, but leaf litter, rotting logs, or grass and sedge clumps are also used. The female then locates or constructs a cavity to deposit her eggs, which takes several minutes for each one and may take several hours for the whole clutch. The eggs have a sticky outer coating, which she uses to adhere to the surrounding moss. Fifteen to 80 eggs, each between 2.5 and 3.0 mm in diameter, are laid. More eggs tend to be laid by larger females. Females often share nests and as many as 1110 eggs have been found in a single nest. Nest availability is thought to be a factor in this communal nesting behavior. Often one or more (usually one) female will stay with the nest for a period, but they are usually gone by hatching. Despite a lack of defensive behavior toward invading predators, the female's nest attendance has been found to increase embryo survival. It is believed that the mother's skin secretions may protect the eggs by impeding fungus growth. So far, no beneficial link has been established between joint nesting and embryo survival. The incubation period varies from 38 to 62 days depending upon the region and local site conditions. Average survivorship after hatching has been estimted at 9 and 21 percent.

Larvae: After hatching the larva wiggle from their nest and drop into the nearby water. They are only about 1.1 to 1.4 cm total body length at birth. During this larval stage they feed primarily on zooplankton and other invertebrates. Their larval period lasts between 23-39 days, which is brief compared to other amphibians. At transformation they are only 1.7 to 2.5 cm total body length. The sex ratio of juveniles is nearly equal.

It takes between two and three years for H. scutatum to reach sexual maturity. Captive specimens have lived as long as nine years but it is unknown how long free-ranging individuals may survive.

The Four-toed Salamander is a Facultative Species and may be found in vernal pools, but can reproduce in other aquatic habitats where they are available.

Natural History: Although conspecific behavior other than courtship is not well documented, it is thought that four-toed salamanders may be slightly aggressive toward each other in defense of territories. These territories are no more than small burrows or shelters such as logs or bark.

If molested by humans or predators a four-toed salamander will curl up, hide its head under its tail and become still. At times they may aggressively posture themselves by lifting their head high and swaying the tail while secreting a mild but distasteful skin toxin. They can also voluntarily detach their tails, which continue to wiggle, possibly distracting predators. This autotomization of their tails in unique. The tails of most salamanders must be grasped to come off.

Little is known about their larval interactions, but behavioral studies have shown a lack of schooling behavior, indicating an inability to recognize kin or conspecific individuals from visual or chemical cues. Schooling behavior is a deterrent to predation and increases health by improving the warm of the environment. Thus, the four-toed salamander’s lack of this behavior likely contributes to their low population densities.

Four-toed salamanders will share breeding sites with ambystomatid salamanders ("mole salamanders") and they have been found sharing microhabitats with other plethodontids such as the red-backed salamander (Plethodon cinereus), although interactions between these species have not been observed. In late autumn four-toed salamanders will gather with each other and other amphibians near overwintering sites. As many as two hundred individuals have been found in one site under leaf litter and inside rotting logs in November. It is presumed that they spend the coldest winter periods underground.

Vernal Pool Conservation

What you can do:

• Resist the temptation to clean up in and around vernal pool habitats. Leave trees, bushes, and understory vegetation, as well as brush, logs, and dead trees.
• Leave a buffer of natural vegetation around the pool for as great a distance as possible back from the edge of the pool's high-water mark. A buffer of at least 100 feet will help maintain water quality, but will do little to protect amphibians living around the pool. Vernal pool breeders require at least 300 yards of natural habitat around their pools in order to survive.
• Do not fill in the pool, even when it is dry, by dumping leaves or other debris in it.
• In areas with more than one pool, try to maintain travel corridors of natural vegetation between them. If some clearing is necessary, avoid drastic alterations that remove most of the trees and other cover. If habitat alterations are necessary, conduct these activities between November and March, when amphibians are less likely to be present. Activities done when the ground is frozen will cause much less damage to the soil than those conducted during warmer months.
• Avoid activities that inadvertently alter the movement of surface water (hydrology) of the upland area that drains into the pool. Digging ditches and similar activities can change runoff into the pool, thereby altering its flooding cycle.
• Do not dig into the bottom of the pool, even when it is dry, as this will disturb the non-permeable layer of soil that allows the pool to flood.
• Work with local conservation commissions and other interested individuals to identify and document vernal pools in your area.

  *Adapted from the Audubon Society of New Hampshire and the Nongame and Endangered Wildlife Program of the New Hampshire Fish and Game Department.

Photo by Tom Lautzenheiser.

A vernal pool is a temporary or semi-permanent body of water, typically filled in the spring by snow melt and spring rain, and holding water for two or three months in the spring and summer.

Vernal pools form in contained basin depressions, meaning that while they may have an inlet, they have no permanent outlet forming a downstream connection to other aquatic systems. They are typically small, rarely exceeding 50 m in width, and are usually shallow. While most are filled with meltwater and spring rains, others may be filled during the fall or with a combination of seasonal surface runoff and intersection with seasonally high groundwater tables. Typical substrates are formed primarily of dense leaf litter. While most vernal pools are found in upland forest, several types have been identified, including floodplain basins, swamp pools and marsh pools.

Periodic drying is a key feature of the ecology of vernal pools. Drying precludes the establishment of permanent fish populations, which would otherwise act as predators on the eggs and larvae of species that live or breed in the pool. While a typical vernal pool is dry during at least part of the year, others may contain some water throughout the year (or for several years), but a combination of shallow water, summer heat, winter freezing, and periodic oxygen depletion prevent the establishment of fish populations.

Terms:

Obligate Species: Species must live or breed in vernal pools.
Facultative Species: Species may be found in vernal pools, but can reproduce in other aquatic habitats where they are available.
Acanthal ridges: Ridges (with light lines) extending from the eyes to the nostrils in spring salamanders.
Costal grooves: The grooves present along the sides of the bodies of many salamanders. When counting them for identification purposes, include only those between the front legs and the hind legs.
Keeled tail: A salamander tail that narrows to a knife edge along its dorsal (top) surface.
Nasolabial grooves: Narrow grooves that extend from the nostrils to the mouth in salamanders of the family Plethodontidae.

Gates, M. 2002. "Hemidactylium scutatum" (On-line), Animal Diversity Web
Accessed March 05, 2004 at
https://animaldiversity.ummz.umich.edu/site/accounts/information/Hemidactylium_scutatum.html

The Roger Tory Peterson Institute is a national, non-profit nature education organization with headquarters in Jamestown, New York, birthplace of world renowned artist and naturalist, Roger Tory Peterson (1908-1996). In collaboration with the Center for Applied Technologies in Education, the Roger Tory Peterson Institute has provided these animal profiles to offer a glimpse into the diversity of Vernal Pools in our region.