- Scientific name: Ambystoma jeffersonianum
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Special Concern (MA Endangered Species Act)
Description
Jefferson salamander is a large, gray to brownish-gray salamander with fine markings of light blue to silvery flecks on the limbs, lower sides, and tail. Adults measure 10-18 cm (4-7 inches) in total length. The tail is laterally compressed (especially in sexually active males) and is approximately the length of the body. Jefferson salamander is in the family of mole salamanders (Ambystomatidae), and so it has distinctively long toes and a stockier build relative to other groups of salamanders in our region. Males tend to be smaller than females and have conspicuously swollen vents during the breeding season.
Larvae have bushy, external gills, a wide head, and a broad caudal fin that extends well onto the back. Young larvae are not easily distinguished from those of other Ambystoma species, but they do appear to have more prominent markings of golden yellow on the sides of the head, neck, and dorsum contrasting with a dark, olive-green to brownish base color. Older larvae can still be difficult to identify, but they are generally characterized as having grayish bodies, whitish/unpigmented undersides, and a heavily dark-mottled caudal fin.
Unisexual Form
Jefferson salamander is a member of an intriguing group of mole salamanders known as the Ambystoma jeffersonianum complex. In Massachusetts, the complex consists of two bisexual species – Jefferson salamander and blue-spotted salamander (A. laterale) – and a group of unisexual Ambystoma of a hybrid lineage. Unisexual Ambystoma in this complex have variable nuclear genomes consisting of complements of both Jefferson salamander and blue-spotted salamander, and a mitochondrial genome derived from streamside salamander (A. barbouri), a species currently occurring in Kentucky, Ohio, Indiana, Tennessee, and West Virginia. The original species pairing that led to the hybrid unisexual lineage is not yet known, but studies suggest that today’s unisexual Ambystoma and A. barbouri from western Kentucky share a maternal ancestor from ~5 million years ago. The unisexual Ambystoma, whose populations almost always consist entirely of females, co-occur with local populations of genetically pure Jefferson salamanders or blue-spotted salamanders and are able to perpetuate through complicated reproductive mechanisms involving the use of sperm from males of either of those two species. The resulting offspring are unisexuals having varying ploidy levels (usually 3-4 sets of chromosomes, but occasionally 2 or 5) and varying complements of A. jeffersonianum vs. A. laterale nuclear genomes (depending on which of the species is present at a given site, and which reproductive mechanism plays out for a given egg). Unisexuals are not recognized as distinct species or subspecies; rather, they are considered hybrid forms of whatever species with which they are breeding. Across the entire geographic range of the lineage, unisexual Ambystoma are known thus far to breed with 5 different mole salamander species. Contrary to a popular, outdated hypothesis, pure Jefferson salamanders do not actively breed with pure blue-spotted salamanders to produce the unisexual “hybrids”.
The unisexual forms of Jefferson salamander are very similar in physical appearance to the pure form, and so they cannot be distinguished in female specimens without genetic or other laboratory analysis. However, one can assume with very high probability that any male specimen encountered in the field is, indeed, the pure form.
Similar Species
Blue-spotted salamander is similar in appearance to Jefferson salamander, but adult blue-spotted salamanders of the pure form are smaller (typically <70 mm [>2.8 in] snout-vent length and <7 g [<0.2 oz]) than adult Jefferson salamanders (typically >80 mm [>3.1 in] snout-vent length and >8 g [>0.3 oz]). In addition, pure-form blue-spotted salamanders have a black base coloration (rather than gray or grayish brown) and more prominent markings (larger, sky-blue blotches rather than smaller, light blue to silvery flecks). Larvae, juveniles, and unisexuals are not readily distinguishable between the two species without laboratory analysis. However, populations of blue-spotted salamander and Jefferson salamander in Massachusetts tend not to overlap; the only places where they are known to occur in proximity are in the towns of Sheffield and Granby. Therefore, geographic location is usually a reliable means for distinguishing the species.
Some people confuse the lead/gray color morph of eastern red-backed salamander (Plethodon cinereus) for Jefferson salamander, as they both have a grayish base color peppered with light-colored flecks along the lower sides. However, eastern red-backed salamander is much smaller and leaner in overall appearance. Perhaps the easiest way to tell the two species apart is to examine the toes. They are very short and stubby in eastern red-backed salamander, but long and fingerlike in Jefferson salamander (even in juveniles). Furthermore, the tail of eastern red-backed salamander is round in a cross-section, whereas the tail of Jefferson salamander is laterally compressed.
A male Jefferson salamander captured from the bottom of a vernal pool in Sunderland, Massachusetts during the breeding season. Note the fingerlike toes and laterally compressed tail.
Life cycle and behavior
As the family name “mole salamander” implies, adult and juvenile Jefferson salamanders spend most of their time underground or hidden beneath rocks, logs, leaf litter, or other debris. During rainy or otherwise humid nights in warmer months of the year, individuals may occur on the ground surface for purposes of foraging, dispersal, or migration to breeding sites. However, most time is spent under leaf litter, in rodent tunnels, or in other subsurface cavities. Winters are spent below the frost line, presumably in vertical rodent tunnels and small spaces associated with root channels or aggregates of stone.
During March or early April (depending on the precise timing of winter thaw and warm, nocturnal rains at a given site), adult Jefferson salamanders emerge from their underground retreats and migrate en masse to vernal pools or other isolated, fishless wetlands to breed. Migrations are typically triggered by a steady rain with ambient air temperature holding above 4.4 °C (40°F) for at least several hours. If favorable weather conditions have arrived before dusk, peak salamander movement tends to occur between an hour after sunset and midnight. Not all individuals migrate on the same night, and not all are able to complete their journey in a single evening. Therefore, migrations may occur over the course of several nights to a couple of weeks, depending on the timing, duration, and frequency of suitable weather conditions. Individuals residing far from their breeding sites may seek temporary cover in small mammal tunnels or beneath moisture-retaining logs, stones, or other objects at the ground surface between migration opportunities. If nocturnal rains are slow to materialize during the normal migratory period, the salamanders may settle for drizzle or a low fog or even migrate beneath the cover of leaf litter (still moist from snowmelt or ground thaw).
Once in their breeding pool, Jefferson salamanders engage in an elaborate courtship like that of blue-spotted salamander. Various stages may be repeated or abandoned multiple times when a female is not receptive, or when competing males disrupt or otherwise interfere with one another, but courtship generally proceeds as follows. The male approaches and swims over a female, clasps her body behind her forelegs (with his own), and holds her for several minutes. During that time, the two salamanders may swim about as a clasped pair or just rest on the pool bottom. Eventually, the male (while clasping the female) begins rubbing his snout over her head, undulates his tail, and rubs his body and cloaca over her body in an increasingly vigorous manner. He then releases the female, moves forward while undulating his tail, and deposits one to several spermatophores on the bottom substrate of the wetland. The female follows him and noses his cloaca, eventually positioning her body over a spermatophore before picking up its seminal fluid and drawing it into her body with her cloacal lips.
In the pairing of males and females of the pure form of Jefferson salamander, reproduction proceeds via normal fertilization of the eggs by the sperm obtained from the spermatophore(s) (i.e., syngamy of haploid gametes). However, in the pairing of males with females of the unisexual form, reproduction proceeds via any of several possible mechanisms (collectively termed kleptogenesis) that do not involve traditional syngamy. In the most common mechanism, the unisexual produces unreduced, polyploid ova, and the male’s sperm merely activates embryonic development in the eggs without contributing any genetic material, thereby resulting in offspring that are essentially genetic clones of the unisexual mother. That unisexuals never produce offspring of the pure form is one reason why unisexual Ambystoma are believed to predominate in most local populations.
After mating, a female Jefferson salamander deposits her eggs in one to several variably sized clusters, each contained within a thin, jelly-like coating. The eggs are deposited underwater, and the coating subsequently swells to form a loose, clear, gelatinous matrix around the eggs. Collectively, the eggs and matrix are called an “egg mass”. Jefferson salamander egg masses typically contain 15-60 eggs each. Egg masses are usually attached to the twigs of fallen tree branches or submerged shrubs, but grasses, forbs, or the pool bottom may be used when twigs are unavailable. One study has suggested that egg masses of pure vs. unisexual forms of Jefferson salamander can often be distinguished by a photographic analysis of the spatial density of embryos within the mass.
Hatching occurs in 3-4 weeks, whereupon the bushy-gilled, fully-aquatic larvae spend the next 2-3 months in the wetland. The salamander larvae feed voraciously on zooplankton, insect larvae (e.g., mosquitoes), and other aquatic organisms, increasing in body size and developing front and hind limbs as spring advances into summer. Metamorphosis then occurs in July or August, depending on when the wetland begins to dry, when food resources become limited, or on other factors. At this time, the larvae seek protective cover beneath leaf litter, logs, woody debris, or other objects in saturated portions of the wetland basin while they develop lungs and resorb their gills and caudal fin. Then, the newly transformed “metamorphs” will wait for an opportunity (typically a nocturnal rain) to leave the basin and disperse into the surrounding forest to begin their lives as terrestrial, juvenile salamanders.
Following dispersal from natal wetlands, juvenile salamanders reside in the forest, feeding on snails, earthworms, beetles, and other small invertebrates. Upon reaching sexual maturity in approximately 3 years, most individuals return to their natal wetland to breed, starting the cycle anew. Others will have sought new ground, joining a different subpopulation within a broader metapopulation, or pioneering a new population of their own.
Maximum life expectancy of Jefferson salamander is unknown, though most individuals that reach adulthood probably live greater than 5 years. A study of the related spotted salamander (Ambystoma maculatum), using skeletochronology as an age-estimation technique, observed peak age distributions at 7 years and 15 years in a Quebec population, with a maximum observed age of 32 years. A 5-year study of salamanders at a breeding pond in Massachusetts observed age ranges of 2-8 years (mean 3.7 years) in blue-spotted salamander and 2-10 years (mean 5.2 years) in spotted salamander. A monitoring project in Maine documented a blue-spotted salamander (unisexual form) that was at least 12 years old.
Distribution and abundance
Jefferson salamander ranges from southern Ontario through New York and western New England south and west to northern Virginia, West Virginia, Kentucky, and eastern Illinois. Its Massachusetts range is restricted to the western region of the state, with scattered populations distributed among parts of Berkshire, Franklin, Hampden, Hampshire, and extreme western Worcester counties. All populations of Jefferson salamander in Massachusetts are presumed to contain unisexuals. Approximately 125 local populations were documented among 57 towns between 2000 and 2024.
Distribution in Massachusetts.
2000-2024
Based on records in the Natural Heritage Database.
Population status
Jefferson salamander (including the unisexual form) is legally protected and listed as species of Special Concern pursuant to the Massachusetts Endangered Species Act (M.G.L. c. 131A) and implementing regulations (321 CMR 10.00). There is anecdotal evidence of declining population size at some sites, and failures to reconfirm presence of the species at sites of previously recorded occurrence suggest a possibility of local population extirpations during the past several decades.
Habitat
Adult and juvenile Jefferson salamanders inhabit relatively mature deciduous and mixed deciduous-coniferous forests and woodlands. Circumneutral to calcareous sites at higher elevations (i.e., not bottomlands) seem to be preferred, with many known populations associated with ridges and rich hillsides. Jefferson salamander is somewhat selective with its breeding habitat in Massachusetts, as the species breeds almost exclusively in vernal pools and isolated shrub swamps. It breeds in abandoned agricultural ponds and man-made impoundments in some situations, but unlike other mole salamanders, Jefferson salamander tends not to breed in wetlands associated with streams or rivers (e.g., maple swamps, marshes, beaver impoundments). Vernal pools and shrub swamps nested between upland ridges (sometimes called “saddle pools”) are used often. The most productive breeding pools appear to be those that are relatively large (0.2-0.5 acres), are deep (3-5 ft), and have patches of multi-stemmed shrubs (e.g., Cephalanthus occidentalis, Cornus spp.). Abundant detritus and absence of predatory fish are additional characteristics of typical breeding habitat. Water clarity seems unimportant, as Jefferson salamander does not appear to exhibit a strong preference for pools with dark, tannic water, as do some populations of blue-spotted salamander.
In the terrestrial environment, well-developed leaf litter, abundant coarse woody debris, non-compacted soils, predominantly closed-canopy tree cover, and abundant rodent tunnels are trademarks of good-quality microhabitat for adult and juvenile Jefferson salamanders. Many sites occupied by the species also contain rock outcrops. Most adult individuals reside within several hundred meters of their breeding wetland. Research suggests that the local distribution of mole salamanders around a breeding site may be influenced by habitat integrity, with salamanders residing closer to a wetland (on average) in intact forest but occupying areas farther from the wetland when a forest patch is fragmented (e.g., by development). Of course, variability in the distribution of high-quality microhabitat around a breeding site is also likely to influence the distribution of individual salamanders around the wetland.
As with other mole salamanders, local populations of Jefferson salamander occur in varying complexity on the landscape. At one end of the spectrum, a resident population is distributed around and dependent upon a single breeding wetland within an isolated patch of forest (i.e., there is no emigration to or immigration from other populations). However, at the other end of the spectrum, multiple subpopulations occur as an interactive network (or metapopulation) across an extensive area of forest containing a multitude of breeding wetlands. Each so-called subpopulation consists mainly of resident juvenile and adult salamanders permanently inhabiting the forest area within several hundred meters of the breeding wetland in which they were born and at which they will subsequently breed. However, some individuals from a given subpopulation disperse away from the breeding site, emigrating to a different subpopulation (and its breeding site), recolonizing the area of an extirpated subpopulation, or pioneering an entirely new subpopulation. Hence, the land areas between and among active and prospective breeding sites provide important dispersal habitat for Jefferson salamander, allowing individuals to move among subpopulations. Generally, upland forest is the preferred dispersal habitat, and the most critical element is that it does not contain major barriers to salamander movement (e.g., vast open areas, extensive vertical structures, roads with high nightly traffic volume). Dispersal habitat is key to the maintenance of metapopulations and the ecological benefits that metapopulation dynamics confer to long-term population viability in the face of environmental and other stressors.
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Threats
Primary threats to Jefferson salamander in Massachusetts are habitat loss, habitat degradation, habitat isolation, climate change, anthropogenic mortality, and disease. These threats may act alone or in combination to cause direct, indirect, and/or cumulative impacts to a given population.
Habitat Loss
The most common types of habitat loss are the clearing of forests and the filling (or ditching) of breeding pools for residential, commercial, industrial, mining, or agricultural development. Perched pools may be lost when blasting activities fracture the underlying bedrock, causing the basin to drain permanently. Jefferson salamanders depend on both upland forest and fishless pools to complete their life cycle, and so substantial loss of either habitat at a site can cause a local population extinction. Habitat loss at smaller scales may disrupt metapopulation dynamics, reduce population size, or otherwise weaken long-term population viability.
Habitat Degradation
Habitat degradation has many forms. Roads, railways, and the various other types of development fragment habitat, creating gaps in the forest and impeding or otherwise disrupting salamander migration and/or dispersal. These open areas present increased risks of salamander desiccation and predation, or they increase travel distances and times for individuals that attempt to go around rather than through such a gap or obstacle en route to a destination (e.g., a breeding wetland). Runoff from roads, parking lots, lawns, crop fields, and other areas introduces chemicals (e.g., petroleum, deicing salts, fertilizers, pesticides) and/or sediments to breeding wetlands, potentially disrupting or inhibiting embryonic development or larval growth and survival. Environmental acidification (acute and chronic) threatens amphibian reproduction in aquatic habitats and may even slow or impede growth in terrestrial habitats. Logging operations disrupt forest ecology (e.g., compact soils, reduce leaf litter, introduce or trigger growth of non-native, invasive vegetation) and, when performed carelessly, create avenues for sediment-laden runoff to enter breeding pools. Excessive trail densities for recreational activities (hiking, biking, horseback riding, dog-walking) degrade habitat by removing leaf litter, compacting or eroding soils, reducing and/or interrupting rodent tunnels, and facilitating unnatural introduction and accumulation of nutrients. Direct dumping of refuse (tires, batteries, oil filters, paint cans, etc.), and yard waste into breeding wetlands is another common form of habitat degradation.
Habitat Isolation
When habitat loss and fragmentation result in local populations of Jefferson salamander becoming isolated (i.e., potential for immigration is eliminated), such populations containing the unisexual form are at risk of long-term decline and extinction, due to the hypothetical “Clanton effect”. Under this hypothesis, unisexuals breed successfully (i.e., obtain sperm from males of the pure form) and produce only unisexuals, which are almost always female. Over time, unisexuals become more abundant at the expense of the pure form, and males are produced at increasingly lower rates as unisexuals outcompete pure-form females for sperm. Eventually, existing males are lost to predation and age and ultimately disappear from the population. Without sperm donors, the remaining population is doomed to extinction. For a unisexual-dominated subpopulation to persist, immigration of males and pure-form females from surrounding subpopulations would be needed so that production of male offspring could continue. When immigration becomes an impossibility (e.g., due to habitat isolation), such populations have low probability of long-term persistence. One study in Ontario appears to have been documenting such a population decline.
In broader landscapes with adequate habitat connectivity, there must be temporal and/or other factors at play to help ensure that not all subpopulations in a metapopulation experience highly skewed unisexual-to-pure-form salamander ratios simultaneously, or else the entire metapopulation would end up on the same track of decline. Genetic sampling work suggests that all Massachusetts populations of Jefferson salamander contain unisexuals, though at varying degrees of relative abundance. Reasons for those differences are not known, but it is presumed that isolated populations will have lower probabilities of persistence. In metapopulations, rescue effect dynamics may be at play, where pure-form individuals recolonize breeding sites of formerly extirpated subpopulations at different points in time and, therefore, each subpopulation in the metapopulation unit is in a different stage of the hypothetical unisexual immigration, production, domination, and extinction cycle. Loss of habitat connectivity and a reduction in the number of connected subpopulations would threaten the benefits of such a safeguard against the Clanton effect.
Climate Change
A 2024 synthesis of climate data, climate modeling, and climate-related research indicates that temperature, total annual precipitation, and frequency of heavy precipitation events are trending upward in the northeastern United States and are expected to continue to do so into the future. A warming and wetting trend might intuitively suggest potential benefits to amphibians, especially to southern species, like Jefferson salamander, whose populations in Massachusetts are near the northern limits of the species’ geographic range. However, the timing, frequency, and intensity of precipitation events are important considerations in evaluating the potential impacts of climate change.
Climate data indicate that the Northeast is experiencing wetter summers and falls and drier winters and springs. Such a shift in precipitation patterns threatens the viability of Jefferson salamander breeding habitat, as some wetlands may begin the breeding period with lower water volumes and – with continued seasonal drought – dry prematurely. Reduced water volumes tend to increase larval density and competition, thereby reducing growth rates. Early pool drying results in substantial or complete reproductive failure, as salamander larvae die before they can complete metamorphosis. Paradoxically, an increasing frequency of heavy precipitation events during early summer also threatens Jefferson salamander larvae, as sudden and large inputs of rainwater may cause spikes in pool acidification and leaching of metals, potentially leading to mass mortality. Larger wetlands with greater water volumes are likely to function as climate refugia under the above climate threat scenarios, but shifts in precipitation patterns do threaten the short- and long-term productivity of smaller breeding wetlands. Climate change could act as a form of habitat degradation for Jefferson salamander by impacting wetland functions and consequently reducing the stability of smaller populations, weakening metapopulations, and facilitating declines.
Anthropogenic Mortality
Like other amphibians, Jefferson salamander is susceptible to direct mortality at the hands of Homo sapiens. Jefferson salamanders are slow-moving and often need to cross over roads to reach breeding sites and/or disperse into suitable terrestrial habitats. Where populations occur near roads with high nightly traffic volumes, adult and juvenile salamanders are killed by automobiles annually. Increases in automobile traffic over time may tip the scales at some sites and send local populations into continual decline. In extreme cases, perpetually high rates of mortality could result in extinction of a local population.
At a smaller scale, Jefferson salamanders are vulnerable to mortality via operation of logging equipment during the breeding migration and juvenile dispersal seasons, when individuals are most likely to be beneath cover objects on the forest floor. Other forms of off-road vehicle operation, especially through breeding pools, may kill, injure, or disturb salamanders.
Disease
Infectious disease has been a significant contributor to global amphibian declines over the past several decades, but impacts in Massachusetts and other parts of New England are not entirely clear.
The amphibian chytrid, Batrachochytrium dendrobatidis (Bd), which is believed to have originated in Asia and spread globally via the pet trade, is a fungal pathogen now prevalent throughout Massachusetts. It is widely blamed for amphibian population declines and extinctions in some parts of the world, but the degree to which it is affecting growth, productivity, and survival in Jefferson salamanders is not known. Generally, the lethality of Bd infection in amphibians is variable, and some individuals do clear infection, but researchers suspect Bd is a common stressor and contributing source of individual mortality in many amphibian populations of Massachusetts.
The related salamander chytrid, Batrachochytrium salamandrivorans (Bsal) – another Asian fungus that is believed to have spread via the pet trade – has yet to be detected in the wild in North America but has devastated populations of the fire salamander (Salamandra salamandra) in Europe. Ambystomatid salamanders appear to be resistant to Bsal infection, though some species in the genus have been shown to be capable carriers. If (or when) Bsal eventually invades the U.S., direct impacts to Jefferson salamander are expected to be minimal. However, the Eastern Newt (Notophthalmus viridescens), which often uses Jefferson salamander breeding wetlands (and preys on the salamander’s eggs) in Massachusetts, is highly susceptible to Bsal and could suffer major population declines.
A third major amphibian disease of concern is the group of viruses known as ranaviruses (family Iridoviridae). Like Bd, ranaviruses are believed to have contributed significantly to global amphibian declines. Ranaviruses are established in Massachusetts and are one of the first suspects when people encounter mass mortality of mature amphibian larvae at vernal pools. Multiple common amphibian species in Massachusetts are carriers and effective spreaders of ranaviruses, and so introductions and outbreaks at Jefferson salamander breeding sites appear to be unavoidable. Sustained or repeated outbreaks at a given breeding site could threaten the local population of Jefferson salamander with reduced productivity and, therefore, long-term decline.
Conservation Action Plan
Some prospective conservation measures for Jefferson salamander in Massachusetts may be grouped into three general categories: inventory and monitoring, management, and research. MassWildlife’s Natural Heritage & Endangered Species Program (NHESP) is the state authority for coordinating and implementing such measures, often in collaboration with other agencies, academic institutions, land trusts, municipal conservation departments, private-sector herpetologists, and others. The NHESP also facilitates participation by the general public.
Inventory and Monitoring
Inventory surveys are essential to discovering undocumented populations or subpopulations of Jefferson salamander on the Massachusetts landscape and to evaluating the relative robustness of each. Knowledge about population abundance and distribution is prerequisite to understanding the conservation status of the species and to making informed decisions about how and where to invest scarce conservation resources for implementation of management strategies. The NHESP, its collaborators, and the public have made strong gains in documenting populations of Jefferson salamander and understanding the state distribution of the species over the past several decades, but undoubtedly there are additional populations to be found and evaluated.
Periodic monitoring surveys are necessary to stay informed about population statuses over time. These surveys provide insight about the effectiveness of certain management strategies, and they serve to detect site-specific threats or signs of population decline or extirpation.
Management
At a local scale, sites of known occurrence of Jefferson salamander should be managed to develop or maintain mature forest conditions within approximately 1,000 ft of confirmed and potential breeding wetlands. Such management should aim to minimize forest loss/fragmentation, road traffic, recreational trail density, soil compaction, and introduction/growth of invasive, non-native vegetation. Forest type should be maintained as deciduous or mixed deciduous-coniferous. Fallen trees, branches, leaves, and other detritus should be allowed to accumulate on the forest floor. Hydrology of breeding wetlands should not be altered in ways that might reduce hydroperiod within the February through August time period. Breeding wetlands should be protected from chemical pollution, and basin structure should not be altered without special permits from the Massachusetts Division of Fisheries and Wildlife and/or the Department of Environmental Protection. Breeding wetlands should not be filled or used for dumping of yard waste or refuse.
At the landscape scale, land area of mature upland forest between local populations (or subpopulations) of Jefferson salamander should be maximized to maintain dispersal corridors and, therefore, facilitate genetic exchange among subpopulations and/or recolonization of formerly occupied habitat. Land acquisition and protection efforts for maintaining habitat connectivity should prioritize areas with low road densities and traffic volumes. A land-protection strategy may best serve long-term persistence of local populations where they occupy relatively large, connected areas containing abundant breeding habitats. However, lands supporting small, peripheral, or isolated populations are also worth protecting for maintenance of genetic diversity at the state level.
Pure populations of Jefferson salamander (i.e., those that do not contain the unisexual form) are not known to occur in New England, and the long-term viability of populations with low pure-to-unisexual salamander ratios is not well understood. Therefore, identification and protection of populations with relatively high proportions of pure individuals is considered an important precaution in a changing environment. Biological inventory, research, land protection, and environmental regulation are among the conservation tools that should be utilized to help meet that goal.
Stronger controls are needed to guard against the introduction and spread of amphibian pathogens and infectious disease. For example, possession of and commerce in amphibian species that are listed as Injurious Wildlife by the U.S. Fish and Wildlife Service due to disease concerns should be regulated at both the federal and state levels. In the natural environment, field biologists, researchers, anglers, and others that enter aquatic habitats should adopt and promote appropriate equipment-sanitation procedures between sites, especially when activities span wide geographic areas. A statewide wetland monitoring program that includes non-invasive sampling for pathogens (e.g., Bd, Bsal, ranavirus) and surveillance for amphibian die-offs is needed.
Active management of Jefferson salamanders and their habitats is a developing interest. For example, construction of vernal pools to enhance breeding opportunities at sites where wetland habitats are scarce is a continuing line of research. Using silviculture to favor growth of deciduous broadleaf tree species, and especially mast-producing species, may be a means to improve habitat at some Jefferson salamander sites by encouraging litter development and higher rodent densities. Removal and control of non-native trees, shrubs, and vines is assumed to benefit the species by facilitating maintenance or restoration of a native community ecology, especially as it pertains to leaf litter, soil chemistry, and invertebrate prey.
Research
Research is necessary to help fill or improve upon knowledge gaps that might otherwise limit the effectiveness of current practices in conservation planning and management. We will never know everything about Jefferson salamander, but some general topics of conservation research interest include:
- Trends in vernal pool hydrological regimes, climate change, and salamander breeding phenology;
- Susceptibility of Jefferson salamander to amphibian chytrid (Bd) and ranaviruses;
- Trends in environmental acidity at Jefferson salamander breeding sites;
- Unisexual and pure-form Jefferson salamander dynamics in isolated vs. connected populations;
- Identification of environmental/habitat variables associated with unisexual-dominated vs. pure-form-dominated populations; and
- Effects of high deer densities on vernal pool ecology and potential for impacts to Jefferson salamander productivity.
Community Participation
The general public is encouraged to participate in the conservation of Jefferson salamander in several ways. For example, observations of Jefferson salamanders should be reported to the NHESP, as land-protection efforts for the species are dependent on knowing where local populations occur. Collection and submission of data for the certification of vernal pool habitat is another beneficial action, as it will afford certain legal protections to salamander habitat. The Massachusetts community may also provide important information by reporting observations of mass amphibian mortality at vernal pools and other wetlands. All Massachusetts residents are urged to be mindful of the weather, plan ahead, and attempt to minimize the number of times they drive through forested landscapes on rainy nights during early spring and mid- to late summer (i.e., when salamanders are most likely to be on the move and attempting to cross over roadways).
Private landowners in areas of Jefferson salamander habitat are encouraged to manage their properties in ways that minimize harm to a local population. Some general measures include maximizing the retention of native tree cover and leaf litter, minimizing landscaping, avoiding use of fertilizers and pesticides, and leaving vernal pools undisturbed (i.e., keeping dogs out during spring and summer, not removing fallen branches or leaf litter, not dumping yard waste in the basin). Landowners may also help to maintain salamander habitat by removing or controlling non-native trees, shrubs, and vines on the property. Another beneficial practice is to maintain vertical guards around window wells to ensure migrating or dispersing salamanders cannot fall into the well accidentally. Conversely, landowners are encouraged to identify other potential barriers to salamander movement (e.g., stonewalls lacking holes or gaps, fences flush with the ground) and do what they can to create openings or gaps to allow salamander passage. Making one’s property “salamander friendly” is one of the best ways for residents to participate in conservation of Jefferson salamander and other species.
References
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Andrews, K.M., J.W. Gibbons, and D.M. Jochimsen. 2008. Ecological effects of roads on amphibians and reptiles: a literature review. Pages 121–143 in J. C. Mitchell, R. E. Jung Brown, and B. Bartholomew, editors. Urban Herpetology. Society for the Study of Amphibians and Reptiles, Salt Lake City, Utah, USA.
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Bogart, J.P., and M.W. Klemens. 2008. Additional distributional records of Ambystoma laterale, A. jeffersonianum (Amphibia: Caudata) and their unisexual kleptogens in northeastern North America. American Museum Novitates 3627:1–58.
Bogart, J.P., J.E. Linton, and A. Sandilands. 2017. A population in limbo: unisexual salamanders (genus Ambystoma) decline without sperm-donating species. Herpetological Conservation and Biology 12:41–55.
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| Date published: | March 28, 2025 |
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