The following account is modified from Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo (©2005 by the Regents of the University of California), used with permission of University of California Press. The book is available from UC Press.

Ambystoma laterale Hallowell, 1856
            Blue-Spotted Salamander

Robert Brodman

1. Historical versus Current Distribution.  The distribution of blue-spotted salamanders (Ambystoma laterale) has been uncertain because of the difficulty in distinguishing these animals from unisexual Ambystoma hybrids.  Recent studies indicate that unisexual populations have a larger range than previously thought (Rye et al., 1997).  Blue-spotted salamanders, the most northern species of Ambystoma, are found primarily north of the Wisconsinian glacial border (Downs, 1989c) and were primary invaders of post-glacial habitat (Holman, 1998).  Today, blue-spotted salamanders are found across southern Canada and the northern United States from eastern Manitoba and Iowa to the Gulf of Saint Lawrence and northern New Jersey (Conant and Collins, 1991; Petranka, 1998).
            Specifically, blue-spotted salamanders are known throughout New York.  Blue-spotted salamanders are widespread in northeast Minnesota with isolated populations in remnant maple/basswood forests in southern counties (Moriarty, 1998).  They previously were known from just 13 Minnesota counties (Breckenridge, 1944), but now are known from 30 counties (Oldfield and Moriarty, 1994).  Blue-spotted salamanders are found throughout Wisconsin except for in the driftless area (Vogt, 1981).  In Ohio, they are known from only four localities in the extreme northwest part of the state (Pfingsten, 1998a).  In Ohio, a search for new populations from 1981–‘82 failed to find any new populations, and no new records of blue-spotted salamanders have been reported in Ohio since then, even though during this time eight new township records have been made of unisexual Ambystoma populations (Downs, 1989c; Pfingsten, 1998a).  There were no new Indiana populations found from 1971–‘94 (Minton et al., 1982; Minton, 2001).
            Remnant populations exist along the periphery of the distribution with isolated populations in Manitoba, Iowa, and New Jersey.  Brownlie (1988) recently found a disjunct population in Nova Scotia.  A population in Jay County, Indiana, was recently discovered that extends the range 110 km south (Brodman, 1999a, 2001).  In New Jersey, blue-spotted salamanders are known only from four wetland regions of the Passaic River basin (Anderson and Giacosie, 1967; Nyman et al., 1988).
            There is evidence of anthropogenic range contraction.  While blue-spotted salamanders were once considered common in the Chicago area (Grant, 1936), Smith (1961) reported only seven populations in northern Illinois.
2. Historical versus Current Abundance.  Blue-spotted salamanders are relatively common in many areas of their range but have declined with the loss of native forests and wetland breeding sites (Petranka, 1998), especially in southern regions.  They are considered Endangered in New Jersey, Iowa, and Ohio, Threatened in Connecticut, and Of Special Concern in Indiana, Vermont, and Massachusetts (Lannoo, 1998d; McCollough, 1999).
            Although rare in southwestern Ontario (Hecnar, 1997), there is no evidence of a blue-spotted salamander decline in Canada (Weller and Green, 1997).  In the United States, they have been considered common throughout the Lake Michigan basin (Pentecost and Vogt, 1976).  Today, blue-spotted salamanders remain common in Michigan, but are abundant only in the northern part of the state (Harding and Holman, 1992).  Populations are stable in northeast Minnesota (Moriarty, 1998).  Only two populations remain in Iowa (Camper, 1988).
            Blue-spotted salamanders are the most abundant salamander species in Wisconsin deciduous and mixed woodlands (Casper, 1998).  They are uncommon and local in areas of Wisconsin where woodland ponds are scarce and populations are becoming more isolated by development in the southeast (Casper, 1998).  Blue-spotted salamanders are common in wooded moraines in northeast Illinois where populations fluctuate, tending to recover in wet years following dry years (Mierzwa, 1998a).
            While found in 11 counties in northern Indiana, blue-spotted salamanders are most common in the Indiana Dunes along Lake Michigan and rare elsewhere (Minton, 2001).  At Jasper-Pulaski Fish and Wildlife Area in northwest Indiana, blue-spotted salamanders were considered plentiful in oak woods from 1946–‘71, but became uncommon by 1995 (Minton, 1998).  They are no longer found in adjacent habitats outside of Jasper-Pulaski where agriculture has isolated the few remaining oak stands (Brodman and Killmurry, 1998).  Blue-spotted salamanders are found throughout New York (Bishop, 1941a; R. Ducey, personal communication) and New England, but are Rare and Threatened in southern New England (DeGraaf and Rudis, 1983; McCollough, 1999) and New Jersey (Nyman et al., 1988).  Acid rain is considered a threat to blue-spotted salamanders in the Northeast (DeGraaf and Rudis, 1983; Knox, 1999).
            Most (70%) of the specimens examined from New York and New England are associated with unisexual Ambystoma hybrids.  Few sites contain only diploid bisexuals (Bogart and Klemens, 1997).  There are only two known pure diploid populations in New England (Knox, 1999).  In northern Indiana, most populations with a blue-spotted salamander morphology consist of unisexual hybrids (including diploid, triploid, and tetraploid animals) that use male small-mouth salamanders (A. texanum) for breeding (Brodman, 1999a, 2001).  Unisexual Ambystoma salamanders are replacing blue-spotted salamanders and small-mouth salamanders in the western Lake Erie basin (Kraus, 1985b).  Some unisexual populations have restricted ranges and are vulnerable to extinction (Petranka, 1998), but conservation of these unisexual populations is difficult because these forms do not fit the biological or evolutionary species concepts on which federal and state conservation laws are based (Kraus, 1995b; see also Goebel, 2003; Minton, 2003).  However, New Jersey and Illinois give protective status to unisexual Ambystoma populations.
3. Life History Features.
            A. Breeding.
                        i. Breeding migrations.  Adults migrate to breeding ponds from late March to early April in the southern parts of their range in southern Michigan (Clanton, 1934), northern Indiana (Brodman and Killmurry, 1998), and northern Illinois (Stille, 1954; Uzzell, 1969).  This migration occurs later in more northern habitats.  Migration takes place in mid April in Wisconsin (Vogt, 1981) and central Ontario (Lowcock et al., 1991) and from late April to early June in more northern parts of the range (Bleakney, 1957; Gilhen, 1974) and on Isle Royale (Van Buskirk and Smith, 1991).  Blue-spotted salamanders typically migrate at the same time as spotted salamanders (A. maculatum) when sympatric (Wacasey, 1961; Nyman, 1991; Talentino and Landre, 1991).  Blue-spotted salamanders tend to be explosive breeders with a breeding season that lasts from a few days (Talentino and Landre, 1991; Brodman and Killmurry, 1998) to 2–3 wk (Clanton, 1934; Uzzell, 1969; Lowcock et al., 1991).  The courtship of blue-spotted salamanders is similar to Jefferson salamanders (A. jeffersonianum), and interspecific breeding isolation is based on chemical cues (Storez, 1969).
                        ii. Breeding habitat.  Blue-spotted salamanders breed in temporary woodland ponds (Wilbur, 1977c; Van Buskirk and Smith, 1991) and are absent where pH is < 4.5 (Karns, 1992).
            B. Eggs.
                        i. Egg deposition sites.  Females attach eggs singly or as masses of 2–15 eggs to aquatic vegetation (Stille, 1954; Bleakney, 1957; Uzzell, 1964; Gilhen, 1974; Wilbur, 1977c; Talentino and Landre, 1991).
                        ii. Clutch size.  Females carry an average of 196–250 ova (Clanton, 1934; Wilbur, 1977c; Minton, 1972, 2001; Gilhen, 1974).
            C. Larvae/Metamorphosis.
                        i. Length of larval stage.  Eggs hatch in 3–4 wk  (Smith, 1961; Minton, 1972, 2001; Talentino and Landre, 1991).  Larvae metamorphose 2–3 mo following hatching (Smith, 1961; Talentino and Landre, 1991).  Blue-spotted salamander larvae develop faster than sympatric spotted salamander larvae (Wacasey, 1961; Nyman, 1991; Talentino and Landre, 1991).  On Isle Royale, average hatchling densities were 12–15/m2 with a high of 158/m2.
                        ii. Larval requirements.
                                    a. Food.  Larvae prey primarily upon microcrustaceans (cladocerans, copepods, ostracods) and aquatic dipteran larvae (chironomids, chaoborids, mosquito larvae; Nyman, 1991; personal observation).  They also eat western chorus frog (Pseudacris triseriata; Smith, 1983) and northern leopard frog (Rana pipiens) tadpoles (personal observations).
                                    b. Cover.  Larvae spend more time in leaf litter and aquatic vegetation than out in the open or in the water column, especially in the presence of larger species of Ambystoma larvae (Jaskula and Brodman, 2000; Brodman and Jaskula, 2002).
                        iii. Larval polymorphisms.  Polymorphisms are currently unknown.  Clanton (1934) and Bishop (1943) noted that there were dark and light forms in many populations of what was then thought to be Jefferson salamanders.  Uzzell (1963, 1964) found that blue-spotted salamanders and Jefferson salamanders were distinct diploid species and that there were two sympatric all-female populations that were unisexual hybrids with triploid chromosome number.  These unisexual Ambystoma populations typically use gynogenetic reproduction, in which the unisexual females use male blue-spotted, Jefferson, or small-mouth salamanders to stimulate egg laying without the incorporation of male genes in the progeny (see the unisexual Ambystoma account by Phillips and Mui, this volume, for an explanation of this phenomenon).  Many genomic combinations of unisexual hybrids are now known between blue-spotted salamanders and Jefferson salamanders (JLL, JJL, JL, JLLL, LLLL, and JLLLL [with initials denoting the species name of the parental genetic component as follows: J = jeffersonianum; L = laterale]), small-mouth salamanders (LT, LLT, LTT, JLT, TTT, JJLT, LLLT, LLTT and LTTT [T = texanum]), and tiger salamanders (JLTi, LTTi and LTTTi [Ti = tigrinum]).  Because of this confusion, little research has been done on the autecology of blue-spotted salamanders.  The historical literature can also be confusing.  Clanton (1934) and Wacasey (1961) performed detailed ecological studies on "Jefferson salamanders" in Michigan.  However, the range of the Jefferson salamanders does not extend into Michigan, so these widely cited studies describing Jefferson salamander ecology must refer to either blue-spotted salamanders or unisexual Ambystoma hybrids.
                        iv. Features of metamorphosis.  Metamorphosis can occur as early as June in the southern parts of their range (Smith, 1961; personal observations) and as late as September in northern locations (Edgren, 1949; Gilhen, 1974).
                        v. Post-metamorphic migrations.  Little is known about post-metamorphic migrations.
                        vi. Neoteny.  Not known to occur.
            D. Juvenile Habitat.  Little is known about juvenile habitat characteristics; they are presumably similar to those of adults.
            E. Adult Habitat.  Adult blue-spotted salamanders are fossorial and most abundant in flatwoods with swamp white oak, wooded moraines (Mierzwa, 1998a,b), moist woodlands with sandy soil (Minton, 1972, 2001), and in remnant maple-basswood forest (Moriarty, 1998).  Blue-spotted salamander numbers are reduced in clearcuts (deMaynadier and Hunter, 1995) and absent from open areas (Mierzwa, 1998b).  Unlike most other members of the genus Ambystoma, blue-spotted salamanders are found regularly under logs (Downs, 1989c; Minton, 1972, 2001; Vogt, 1981).  Blue-spotted salamanders are more tolerant of dry, sandy conditions than other salamanders in their range (Minton, 1972, 2001; Vogt, 1981).  Blue-spotted salamanders are considered to be a forest management-sensitive species (deMaynadier and Hunter, 1998).  In Maine, they occur in habitats perpendicular to silviculture edges that have good conifer and hardwood canopy, litter, bole-root, and nonvascular plants.  They are less common in areas with good ambient light, mid story cover, and woody cover (deMaynadier and Hunter, 1998).  The depth of edge effects was estimated to be 25–35 m from areas of silviculture.
            F. Home Range Size.  Home range size has not been studied in blue-spotted salamanders.  Because of their smaller size, their range may be smaller than of other Ambystoma.
            G. Territories.  Unknown.  Adult LLT unisexual salamanders will aggressively defend burrows from intruders (Ducey, 1989; Ducey and Heuer, 1991).
            H. Aestivation/Avoiding Dessication.  Aestivation is unknown; animals likely avoid dessicating condition by seeking shelter under cover objects or burrowing.
            I. Seasonal Migrations.  The only documented migrations are those associated with breeding (adults to/from breeding sites in the spring) and migrations of newly metamorphosed animals from breeding sites in the summer.
            J. Torpor (Hibernation).  Blue-spotted salamanders are a terrestrially hibernating species.  Individuals are freeze intolerant and are thought to overwinter by burrowing below the frost line (Storey and Storey, 1986).
            K. Interspecific Associations/Exclusions.  Larvae co-occur with a wide variety of amphibians at breeding sites.  They commonly breed at sites with spotted salamanders, wood frogs (Rana sylvatica), spring peepers (Pseudacris crucifer), and western chorus frogs in Wisconsin (Vogt, 1981); they coexist at breeding sites with all of the amphibian species found in northern Indiana, including potential predators such as American bullfrogs (Rana catesbeiana), eastern tiger salamanders, eastern newts (Notophthalmus viridescens), and lesser sirens (Siren intermedia; personal observations).  Blue-spotted salamanders often share breeding ponds with unisexual Ambystoma populations in the southern half of their range.  Mechanisms that allow unisexual salamanders to coexist with blue-spotted salamanders are poorly understood (Petranka, 1998).  Blue-spotted salamanders and JLL unisexual salamanders experience density-dependent effects due to interspecific competition among larvae in experimental enclosures (Wilbur, 1971, 1972; R.B. and H.D. Krouse, unpublished data).  Larval aggression in natural populations is the primary mechanism regulating density-dependent growth and survival (Wilbur, 1971, 1972; Van Buskirk and Smith, 1991).  Blue-spotted salamander and eastern tiger salamander larvae facilitate their coexistence by partitioning microhabitats; blue-spotted salamander larvae will use refugia (Jaskula and Brodman, 2000; Brodman and Jaskula, 2002).  Little is known of interspecific interactions among juveniles and adults.  When placed together, adult tiger salamanders will attempt to eat adult blue-spotted salamanders (personal observation).
            L. Age/Size at Reproductive Maturity.  In Michigan, juveniles mature in 2 yr (Wilbur, 1977c).  Males mature at a minimum of 42–45 mm SVL, females at 51–52 mm SVL (Uzzell, 1967b; Gilhen, 1974; Licht, 1989).
            M. Longevity.  Blue-spotted salamanders were not included among the species that have captive longevity records (Bowler, 1977).  No studies using skeletochronology have been conducted on these animals.
            N. Feeding Behavior.  Larvae are opportunistic, gape-limited predators; active foragers that stalk and pursue prey (Jaskula and Brodman, 2000; personal observations).  Stomach contents of juveniles and adults indicate that blue-spotted salamanders eat a wide variety of invertebrates, but most commonly beetles, spiders, centipedes, earthworms, and slugs (Judd, 1957; Minton, 1972, 2001; Gilhen, 1974; Vogt, 1981; Bolek, 1997).
            O. Predators.  Larval activity is reduced at low pH levels (< 5.0–4.5), which may make larvae more susceptible to predation (Brodman, 1993; Kutka, 1994).  Predaceous diving beetles (Coleoptera), adult eastern newts, lesser sirens (personal observations) and tiger salamander larvae (Jaskula and Brodman, 2000) eat blue-spotted salamander larvae.  Juveniles have been observed to be preyed upon by wolf-spiders (Arachnida; McLister and Lamond, 1991).
            P. Anti-Predator Mechanisms.  Adults curl their bodies and elevate and lash with their tails (Brodie, 1977).  Larvae seek refuge and reduce activity when in the presence of larger Ambystoma larvae (Jaskula and Brodman, 2000; Brodman and Jaskula, 2002) and adult newts (personal observations).
            Q. Diseases.  Little is known of diseases of blue-spotted salamanders.
            R. Parasites.  Trypanosome protozoans have been detected in blue-spotted salamanders and JLL hybrids where as many as 26% of the salamanders in a sample from a given year may be infected (Woo and Bogart, 1986).  An apicomplexian protozoan (Hepatozoon clamatae) that infects several sympatric amphibian species does not infect blue-spotted salamanders (Kim et al., 1998).
            Other parasites include the flukes Rhabdias ranae, Spiroxys sp., Thelandros magnovulvaris, Brachycoelium salamandrae, echinostomes (Muzzall and Schinderle, 1992), and the nematode Cosmocercoides dukae (Bolek, 1997).  These nematodes can be present in as many as 50% of the salamanders in a population and is correlated with the number of slugs in the stomach contents (Bolek, 1997).
4. Conservation.  The main threats to blue-spotted salamanders are habitat destruction, land use, and acidification of breeding ponds.  They need undisturbed upland forest sites (Downs, 1989; deMaynadier and Hunter, 1998; Petranka, 1998) with temporary woodland ponds (Wilbur, 1977; Van Buskirk and Smith, 1991) and pond pH > 4.5 (DeGraaf and Rudis, 1983; Karns, 1992; Knox, 1999).  A radius of 164 m around breeding ponds needs to be protected as core upland habitat (Semlitsch, 1998).  A study on a population of blue-spotted salamanders in Wisconsin suggests a 147 m core of upland habitat (J.M. Jaskula, personal communication).  Blue-spotted salamanders are sensitive to forestry management (deMaynadier and Hunter, 1998) and agriculture (Brodman and Kilmurry, 1995; Petranka, 1998) practices.  Silviculture produces an edge effect ≤ 35 m that impacts blue-spotted salamander populations in adjacent undisturbed habitat (deMaynadier and Hunter, 1998).  Therefore a buffer of at least 35 m should be added to protect core upland habitat, suggesting a radius of 182–199 m is necessary to conserve blue-spotted salamander populations.
            Because unisexual larvae often outnumber blue-spotted salamanders in the southern portions of their range where they are syntopic (Uzzell, 1964; Nyman et al., 1988; Bogart and Klemens, 1997; personal observations), competition with unisexual populations may limit the distribution and abundance of blue-spotted salamanders (R.B. and H.D. Krouse, unpublished data).

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Sep 2024.

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