Amphibians of Michigan
Probably our most common Mole salamander, the Blue-spotted Salamander is easily distinguished from other Michigan salamander species by its dark color and light blue flecking. Some individuals may closely resemble this species but are actually unisexual hybrids which I will cover later. This species is a denizen of a wide variety of habitats in Michigan which include upland forest, lowland forest, and even the edges of some open fields. However, they are always associated with nearby vernal pools for breeding purposes.
Unlike the spotted salamander, this species does not lay its eggs in large clumps but rather attaches a single egg to cover within a breeding pool. Although eggs may be seen in close proximity to one another, they are never in one large organized clump. Blue-spotted salamanders can be found more readily throughout the year as well. They are usually found under logs, rocks, or other sorts of cover throughout the season and especially a day or two after a rain shower.
Unisexual Hybrid Salamander
A lot of salamanders in Michigan may look somewhat odd, like a weird blue-spotted salamander that seems to share characteristics with other species of Mole salamander. The identity of these oddballs is one of great complexity and many biological questions. This is a unisexual hybrid salamander, an all female complex consisting of five parent species of Mole salamander which include A. laterale, A. texanum, A. barbouri, A. tigrinum, and A. jeffersonianum. This unique group of salamanders utilizes a breeding strategy known as kleptogenesis, a method of reproduction whereby a female ‘steals’ sperm from a sympatric sexual male. The sperm is required to stimulate an egg to divide (gynogenesis) but does not fertilize the egg and may or may not contribute chromosomes to the offspring. This unique form of reproduction is thought to have originated about 5 million years ago within this unique group of salamanders.
Because of their unique mode of reproduction, individuals often have more sets of chromosomes than usual. Unisexuals can be triploid (three sets), tetraploid (four sets), or even pentaploid (five sets). This occurs because of the female "stealing" genetic material from males of sexual species it shares breeding ponds with, however sperm genomes are often discarded and thus the resulting reproduction is asexual. Occasionally the sperm genome is used and passed on to the offspring. This complex mode of reproduction can result in over 20 different genomic combinations among the five contributing species. Most animals in Michigan are LLJ (laterale, laterale, jeffersonianum) or LJJ (laterale, jeffersonianum, jeffersonianum) but some may be tetraploid or pentaploid. It should be noted that the latter do not seem to do well in the wild, likely do to the unusually high amount of chromosomes.
Most individuals in this group are triploid, which begs an important evolutionary question; why? There would have to be an advantage to these individuals over diploid, tetraploid, or pentaploid individuals for there to be such an abundance of this biotype over the others. Other interesting questions are also at hand, unisexuals usually share breeding ponds with contributing species but in some cases they are only found in breeding pools with the Spotted Salamander (Ambystoma maculatum). No unisexual has ever been recorded to contain genetic material from A. maculatum and unisexuals often lay infertile egg masses. Are these infertile eggs the result of the inability of the unisexuals to utilize the maculatum genome, or are the unisexuals simply using the sperm of male spotted salamanders do initiate cloning? These any many other questions are important to better understanding the origins of this unisexual complex and their presence in the Great Lakes region in the future.
This brightly marked species is easily distinguishable from most of Michigan's salamander species in that is exhibits a dark background with two rows of bright orange or yellow spots down its dorsum. The number of spots may vary greatly among individuals may have few but very distinct spots, while others may have many which are smaller in size. In Michigan, some individuals exhibit orange spots on the head while the spots on the body are much more yellow in coloration. Although it is a common species in Michigan, the Spotted Salamander is not usually observed outside of the breeding season it early spring. At this time of the year, spotted salamanders migrate to temporary woodland pools known as vernal pools to breed.
Migration occurs on warm, rainy nights in late March or early April. Salamander emerge and migrate to vernal pools where males often congregate in huge numbers around a single female and perform a "tail dance" in the water to impress the female. Each male drops several packets of sperm known as a spermatophore which contains all the genetic material to pass on to the next generation.
A female will take a single spermatophore into her cloaca, which fertilizes the eggs which she is carrying. After a day or two the eggs will be fully fertilized and the female will remain in the pool until she lays her eggs. Spotted Salamander females often attach egg masses to twigs, leaf litter, or other material within the vernal pool as the female which is shown below ovidepositing her eggs to some leaf litter.
The larva hatch and spend the majority of the year in the pool until they metamorphose into miniature adults and then head into their terrestrial lifestyle. This species in common in Michigan, but occurs in scattered locations where suitable habitat exists. Get out in the woods on a rainy spring night and you just might glimpse one of these gorgeous salamanders.
One of the most visually striking Ambystomatids, the marbled salamander is easily identified by it's black and white coloration. Adults are short and stout, attaining lengths between 3.5-5". This species is most recognizable by it's black background coloration and white or gray markings which usually form bars across the back and tail. This species is sexually dimporphic; females tend to have gray markings, while males feature bright white markings. Juveniles look like miniature versions of adults, but tend to have light gray markings like those of adult females.
The natural history of this species in Michigan is poorly understood. The first specimen was not found in the state until 1950 in the southwestern lower peninsula. Only a handful of specimens have been documented in the state, the last one being in 1989. It has only be documented in Berrien, Van Buren, and Allegan counties and it is likely that it is extirpated in the state. Throughout their range, marbled salamanders are known to inhabit moist lowland forests and adjacent upland forests where they are often found under logs and the leaf litter. This species is different than other Ambystomatids in that it is a fall breeder. Females lay eggs under logs and other cover during the fall and await the fall rains to fill the dried pools that other species use during the spring months. It's unclear to what breeding habits or habitats this species utilizes in Michigan because of the lack of documentation, but it's likely that Michigan individuals follow the same ritual. Documentation of this species in Michigan would be very exciting, so any observation of it should be reported promptly to the Michigan Herp Atlas.
This small and odd looking species is rarely seen in Michigan. The smallmouth salamander gets its name from its characteristic short, blunt snout which makes it look like it has run head first into a wall. It is a medium sized Ambystomatid that is usually dark or gray in coloration and often has lighter gray flecking, giving it a sometimes "frosted" appearance.
This species reaches its northern range limit in extreme southeast Michigan, unfortunately this is also home to Michigan's population center and is extremely developed. Though this species was probably not very common historically, its breeding habitat has become fragmented and lost and there are now only a handful of breeding populations left.
As you can see, human habitation is on the bordering edge of this site and is the main reason for decline of the smallmouth salamander in Michigan, it is listed as an Endangered species here. It is one of the earliest breeding species in Michigan and may be found sharing pools with Eastern Tiger Salamanders. Any sightings of this species should be reported to the Michigan Herp Atlas.
Eastern Tiger Salamander
This large and robust salamander is the largest species of terrestrial salamander which occurs in North America, with some adults reaching over a foot in length. It is rarely seen outside of the breeding season, with the exception of the 4-5 inch juveniles which emerge in late summer around breeding sites. Tigers are easily distinguished from any other Michigan salamander by their sheer size, large head and oversized jaw, and the large protruding eyes. Some individuals may exhibit brilliant blotches of golden yellow or light brown, while others are extremely dark with very little noticeable pattern. This species is sexually dimorphic, which means males can be distinguished from females by their physical appearance.
Adult male, exhibiting flat rudder-like tail
Adult female, exhibiting rounded tail
Males have a characteristic vertically flattened, rudder-like tail while adult females exhibit a more rounded, tapered tail. Adults are rarely seen outside of the breeding season which occurs in early to mid March. Tigers are one of the earliest breeding salamanders in Michigan and often enter breeding pools with plenty of remaining ice cover, all that is needed is a few feet of the edges to be thawed.
Females and males spend a few days in breeding pools for a few days and that head back underground for the remainder of the year. Metamorphs emerge in late summer and resemble adults but can range from 3-5 inches and are usually dark in coloration.
Southern Two-lined Salamander
This beautiful species is one of two extremely unique species of Plethodontid salamanders which inhabit Michigan. It is easily characterized by its bright yellow coloration and two distinct dark striped running down the dorsum. The sides may be darker in appearance than the dorsum between the lines, which is often lines with small dark spots. Some individuals maybe duller in appearance than others, while some are very brightly marked.
In Michigan, the Two-lined Salamander's ecology is mostly unknown. It was discovered to inhabit a small stream only a few years ago and ongoing research is continuing to help better understand its place in the state. Genetic work determined that the Two-lined Salamanders which inhabit Michigan are the southern subspecies; Eurycea cirrigera, but as to its origin whether native or introduced is still unknown.
This roaring brook is home to the Two-lined Salamander, though its current is not usually as violent as pictured above which was due to heavy rainfall the night before. Protecting this site and continuing research on the Two-lined Salamander will help to ensure its status in Michigan for years to come. It is extremely unlikely to come across this species in the state as they are exceedingly rare and localized, but any sighting should be reported to the Michigan DNR or to the Michigan Herp Atlas.
Northern Dusky Salamander
Like the Two-lined Salamander, the Northern Dusky Salamander wasn't discovered until a few years ago in Michigan. It is a robust salamander which is extremely variable in cover, with some individuals being very dark in coloration while others exhibit bright hues of red. The genus name Desmognathus, comes from the Greek words desmos and gnathos, meaning ligament and jaw respectively. This refers to the large bundle of ligaments around the jaw which gives the members of this genus a large, bulging jaw in appearance. Another distinguishing characteristic for this species is the presence of a light diagonal line which extends from the back of the eye to the corner of the jaw, it is easily visible in both of the animals shown here.
Duskies are denizens of streams, seepages, and any habitat in which a trickling water source is nearby. Like the Two-lined Salamander this species is only found at one location in Michigan, a clear stream amid a mature Eastern Hemlock forest. In the early summer, females lay eggs on the undersides of rocks, logs, leaf litter, and other forms of cover. The hatching larva are completely aquatic and have well developed gills which eventually diminish over time.
Larva like the one shown above often have traces of adult coloration and usually have 6-8 faint spots which are visible on the dorsum. They retain this characteristic as they age but eventually it becomes faint or lost altogether amongst other patterning. It is extremely unlikely to come across this species in the state as they are exceedingly rare and localized, but any sighting should be reported to the Michigan DNR or to the Michigan Herp Atlas.
This small, secretive species is found statewide in a scattered locations where suitable habitat occurs. The Four-toed Salamander gets its name from the presence of four digits in the hind feet, while most salamander species have five digits on the hind feet. It is small in size and is generally gray in coloration with a rusty-orange tail and nose, and it may have light colored flecking along its flanks. The underside exhibits the best diagnostic character for this species, a white or cream belly with scattered black spots. There is also a noticeable constriction at the base of the tail which is not present in other Michigan salamander species which allows the Four-toed Salamander to drop its tail if necessary to avoid a predator.
Four-toed Salamanders are fairly common statewide, but may be difficult to encounter in the field as they are quite habitat specific. They are usually associated with sphagnum moss, but may also be found in and around bogs, seepages, and some vernal pools.
Females seek out sphagnum moss in the late spring and a lay a clutch of eggs within the moss and stand guard until they hatch. Though they can often be found by pulling back moss around this time, it is best to leave them be and not risk damaging eggs in the process. Though this species is likely common statewide, its current distribution within Michigan is poorly understood, so any sightings should be reported to the Michigan Herp Atlas project.
This colorful species is by far the most common species of salamander which inhabits Michigan. It is easily characterized by the red stripe which runs down its dorsum. However, this species comes in both a "redback" and "leadback" color phase.
The reason that this species is so common statewide is because of its general habitat preference. Redbacks are almost always associated with deciduous forests which may include northern hardwoods, oak-hickory, or beech-maple forests and can be found in either uplands or lowlands. They are often found under rocks, logs, leaf litter, and other sorts of debris on the forest floor.
These large aquatic salamanders are the largest species of amphibian which inhabits the state, with adults ranging from 8-15 inches. Mudpuppies are neotenic, meaning that they retain larval characteristics through adulthood. In the case of this species, the external gills which most larval amphibians have are never lost as mudpuppies mature, making them a permanent resident of aquatic environments. They prefer cool, oxygen rich waters with plenty of rocks for them to hide underneath. In Michigan, mudpuppies inhabit clear creeks, rivers, and deep inland lakes.
The rock strewn shorelines and bottoms of this large river in urban southeast Michigan provides ideal habitat for this species. Mudpuppies seem to be more commonly encountered in clear inland lakes further north in the state. Adult mudpuppies tend to be dark in color, usually having spots along the dorsum. Juveniles are much brighter in coloration and have two bright mustard yellow stripes down each side of the body, the stripes may also contain dark mottling.
This species is found statewide, but it's distribution in not entirely known. Any mudpuppy sightings should be reported to the Michigan Herp Atlas to help better understand this large aquatic salamander's distribution across Michigan.
Michigan's Frogs & Toads
Blanchard's Cricket Frog
Acris crepitans blanchardii
Blanchard's cricket frogs are quite small with adults averaging between 0.5-1.5" in length and are extremely variable in color. They may be tan, gray, or olive in coloration with additional dark mottling on the sides and limbs. Some even have a light line running down the back with may be green or red in color. One the best diagnostic characters for identification is the light line which runs diagonally from the eye to the corner of the jaw. Another good field mark is the pigmentation which often forms a dark triangle on top of the head between the eyes.
This small species of frog was historically common across the southern lower peninsula, this species has suffered drastic declines in Michigan due to the loss of it's habitat. Blandchard's cricket frogs inhabit a wide variety of habitats including bogs, prairie fens, lake edges, and sluggish streams and are often found in the open mud flats and shorelines of these areas. Small streams and pools in prairie fens like the one pictured above serve as ideal habitat. Breeding occurs in May and June when males begin to call. The call is similar to the sound of pebbles being tapped together and this series of clicks can last for up to thirty seconds, starting at a low tempo and increasing in frequency. The Blanchard's cricket frog is listed as a Threatened species in Michigan and any observations should be reported to the Michigan Herp Atlas.
This is the well known toad that often shows up in backyards, but this species can be found in a wide variety of habitats. The American toad can easily be identified by it's plump stature and warty skin. Though it is usually tan in coloration, this species is incredibly variable and may be brightly colored or may be almost completely black. The only species in the state that is can be confused with is the Fowler's Toad (Bufo fowleri). Both are similar in size and stature, but the American toad only has 1-2 warts per dorsal spot, while the Fowler's toad often has 3-4 warts per spot, the Fowler's toad also has a light colored belly with a few dark spots.
The American toad is a habitat generalist and may be found in open woodlands, open meadows, marshes, and even in suburban backyards. Breeding takes place in early spring and often involves large numbers of toads congregating in ponds and pools. Sometimes, hundreds of individuals may be found in one spot like the photo above. The call is a loud, musical trill which can last up to thirty seconds.
This is the less common of Michigan two species of toad and is restricted to the southern and western lower
Fowler's toads prefer open sandy habitats such as dunes and sandy pine forests, but also may be found in suburban backyards on the west side of the state. They spend much of their time burrowed into the ground in these dry, xeric habitats and are a favorite food of the Eastern Hognose Snake (Heterodon platirhinos). Breeding occurs in May and June on rainy nights and the call of this species makes it easily distinguishable from the American toad. The call is a short, bleating cry which lasts about 3-5 seconds and sounds like "waa."
Eastern Gray & Cope's Gray Treefrogs
Hyla versicolor / chrysoscelis
Our only two native treefrog species, the Cope's & Eastern Gray treefrog are completely indistinguishable without hearing their call or looking at their genetics. Their skin is warty and moist, and often features a base coloration and scattered darker markings. Some individuals may have a gray or white background color, while others may even be a bright green. The best diagnostic characters for these two species are the large toe pads and the dark line which extends from the eye to the hind leg. The inner thighs are also bright yellow on both species.
The skin secretions of both species are toxic and are strong eye irritants which can be quite unpleasant if the eyes are rubbed after handling one, it is always wise to wash your hands after handling one to avoid an unpleasant experience. Treefrogs are founds in a wide range of habitats including deciduous or mixed forests, farm woodlots, swamps, old fields, and well-vegetated yards or suburban areas.They breed in vernal pools, hardwood swamps, and other semi-permanent bodies of water from May through July on warm, rainy nights. The call of the Eastern Gray is a loud, musical trill which lasts from 1 to 3 seconds. The call of the Cope's Gray is a faster and harsher trill which also lasts 1 to 3 seconds, but is more nasal in tone. Temperature can affect the intensity and duration of a call, so it can be difficult to distinguish these species from one another in the field based on call alone.
Northern Spring Peeper
Pseudacris crucifer crucifer
One of the most recognizable and earliest species of frog which calls in the spring, the Spring Peeper is one of the more common frogs in Michigan. It is a small frog that is generally around 1" in length and has a characteristic "X" on it's back. It may be brown, salmon, or gray in coloration and often features other dark pigmentation across the limbs. It also has small toe pads which make it a member of the treefrog family, like all other North American chorus frogs. This species is most often encountered in the early spring near breeding pools in woodlands, marshes, and other areas where hundreds of individuals may form a large chorus on rainy nights. The call is a loud, high pitched "peeep" which lasts which is repeated about once a second. Males may also voice a low-pitched whistle which is likely a territorial response to another male encroaching on its calling site.
Western Chorus Frog
Pseudacris triseriata triseriata
Like the Spring Peeper, the Western Chorus Frog is one of the earliest and most recognizable spring breeders in Michigan. It is a small frog that is generally around 1" in length and usually has three characteristic stipes running down it's back, though they are sometimes quite faint like individual above. It also has a noticeable cream stripe along the upper lip which is bordered by a darker band which stretches through the eye. It also has small toe pads on its feet. It is encountered almost exclusively during the early spring breeding season when it calls in huge numbers in marshes, vernal pools, and even roadside ditches. The call is a loud, scratch "cree-ee-ee-ek" which can be likened to the sound of pocket comb being strummed with a fingernail, the call is repeated about once every few seconds in a full chorus.
The bullfrog is the largest species of frog which inhabits Michigan, with adults topping out 3-8" snout to vent. Bullfrogs inhabit a wide variety of habitats including marshes, lakes, ponds, and sometimes slow moving streams. They are voracious predators which eat anything smaller than them, sometimes even smaller frogs or neonate snakes. This species is also sexually dimorphic, meaning you can tell the difference between males and females by their appearance. The tympanum of males is much larger than the eye, while a female's tympanum is about the same size as the eye. Males are typically lager than females and often have a bright yellow throat. The only other species the bullfog may be confused with in Michigan would be the Northern Green Frog (Rana clamitans melanota). Young bullfrogs are often the same size and color of an adult green frog, but lack the two dorsal lateral folds which run from the eye down the back in the green frog, bullfrogs have a smooth back. Breeding occurs in mid-summer and males can call in the evenings or at night with a deep, resonating "brr-rum."
Northern Green Frog
Rana clamitans melanota
Probably our most common and widespread frog species, the Northern Green Frog can be found literally anywhere water is present in Michigan. They can be found in ponds, lakes, creeks, marshes, rivers, and even in roadside ditches. Adults are typically 2-5" in length and are extremely variable in coloration. Most have at least a little green around the head and snout, while the rest of the body may be green, brown, and even yellow in color with or without dark mottling. Thought similar in appearance to young bullfrogs, green frogs have two dorsal lateral folds which run from the back of the eyes to the dorsal lateral ridge. Breeding occurs in early to mid summer, the call is a short note that sounds like someone plucking a banjo string.
A rather uncommon species in the Great Lakes region, the pickerel frog isn't seen as commonly as it's look alike, the northern leopard frog. This species prefers cool waters and inhabits bogs, prairie fens, cool sandy streams, and other adjacent habitats associated with these areas. In Michigan, the pickerel frog is usually found on the west side of the state, though they are occasionally found in scattered locations in southeast Michigan. Pickerel frogs range from 2-3" as adults and do not get as large as their counterparts. Pickerel frogs are usually usually light tan in coloration with prominent, rectangular spots down their back and sides. The blotches are usually more rectangular and organized than those of the leopard frog. The dorsal lateral folds are always light in color, and the inner thighs are bright yellow. This bright color also helps distinguish this species from the leopard frog. Breeding takes place in April and May. The call of the pickerel frog is a low-pitched, snore-like croak.
Northern Leopard Frog
Much more common than the pickerel frog, leopard frogs denizens of ponds, marshes, lake and stream edges, and upland fields which are adjacent to these areas. On humid mornings with plenty of dew, they can be found in large numbers in meadows before it becomes too hot. This species is extremely variable in color, some individuals may be bright green or brown with scattered spots, like the individuals pictured above and below.
Though sometimes quite similar in appearance to the pickerel frog, the spots of the leopard frog are usually more numerous and less rectangular in appearance. The spots are often also bordered by white or yellow, and the dorsal lateral folds are usually a light coloration. Breeding occurs in April and May, and the call is a low, rumbling snore with interspersed with hoarse croaks.
One of our more common frog species, the Wood Frog is an explosive breeder which is amongst the first species to call in the spring. Wood frogs typically begin breeding in late March or early April with the first warm rains of spring, often in huge numbers in marshes, vernal pools, and other semi-permanent bodies of water. The call is a series of sporadic clucks, a large chorus of this species sounds like a large group of ducks from a long distance away. Like the name implies, wood frogs are denizens of deciduous, conifer, and mixed forests with ample breeding sites. They can be brown, bronze, gray, or even pink coloration. The best diagnostic characters for this species are a dark mask extends through the eye and a white stripe along the upper lip.