Ambystoma laterale Hallowell, 1856
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).
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).
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,
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,
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
3. Life History Features.
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
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,
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).
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
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
vi. Neoteny. Not known to occur.
D. Juvenile Habitat.
Little is known about juvenile habitat characteristics; they are presumably similar
to those of adults.
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
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
Unknown. Adult LLT unisexual salamanders will aggressively defend burrows from
intruders (Ducey, 1989; Ducey and Heuer, 1991).
Aestivation/Avoiding Dessication. Aestivation is unknown; animals likely avoid
dessicating condition by seeking shelter under cover objects or burrowing.
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.
(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).
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
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).
Blue-spotted salamanders were not included among the species that have captive longevity
records (Bowler, 1977). No studies using skeletochronology have been conducted on
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).
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).
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
Little is known of diseases of blue-spotted salamanders.
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).
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.
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).
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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