Special Note: This species is very easily confused with the much more common (in Minnesota) tiger salamander. Some tiger salamanders look very much like spotted salamanders. Spotted salamanders are very rare and have a restricted range in Minnesota. Please read the Description Section below very carefully.
The spotted salamander was first documented in Minnesota in May 2001. (C. Hall personal communication). We have yet to determine their range and abundance in Minnesota. Spotted salamanders will have no official status in Minnesota until we know more information. If you find a salamander fitting the spotted salamander description below, please contact us or the DNR!
This is a rather large salamander reaching lengths of 6 to 7 3/4 inches long (Conant and Collins, 1991). Adults have a black, bluish black, or gray ground color with two rows of round yellow or orange spots running lengthwise down the back. The rows of spots may be irregular or straight. The spots run from the eyes to the tail tip and are usually well rounded and do not run together to form large blotches or lines. Some individuals have two bright orange spots on the head that stand out against the bright yellow spots on the body and tail. The belly and lower sides are slate gray and lighter than the dorsal ground color.
Often there are silver fleckings present on the sides. In adults, the bottom lip and throat are light gray. They have 11 to 13 costal grooves and there are four toes on the front feet and five toes on the back feet. Larvae are olive green above, lighter colored below, and have no strong markings except near the tail tip. They also have bushy gills. Newly tranformed spotted salamanders have light bellies and smaller dorsal spots (Petranka 1998).
Spotted salamanders look very similar to tiger salamanders. They may be distinguished from one another by the following: spotted salamanders have 1) rounded bright yellow spots arranged in two irregular rows down back and tail and (in some) a pair of orange spots on the head, 2) light gray sides and belly with silver flecks, 3) in adults, lower lip and throat are light gray. Tiger salamanders have 1) large yellow or olive blotches that are scattered or often connect forming a network and no orange spots at all, 2) belly is olive or blackish and yellow from sides extends onto belly, but no silver flecks, 3) in adults, lower lip is usually bright yellow and throat is yellowish olive.
There are no recognized subspecies of the spotted salamander, Ambystoma maculatum.
Known only from Pine and Carlton counties in Minnesota at this time. Spotted salamanders have a large national range in states east of Minnesota and may be more common those states.
Spotted salamanders require woodlands with ponds for breeding. Petranka (1998) states that mature deciduous forest is the main habitat type for the spotted salamander, but Minton (1972) also makes note of mixed hardwood habitats. Vernal pools are very important for breeding. Fish free ponds are best, but Figiel and Semlitsch (1990) found that larvae may change habitat usage to survive in ponds containing fish.
Spotted salamanders are obviously one of the most secretive salamanders in our state, which is why they have gone undetected for so long. Nearly all of their time is spent underground in burrows of other animals. Occasionally, they are found above ground on damp or humid nights. The only time they are found above ground in numbers are during heavy spring and fall rains while they migrate to and from overwintering sites. It is not known how visible these migrations are in Minnesota.
Spotted salamanders breed early in the spring, but slightly later than some of our first spring amphibian breeders. The adults migrate to the breeding ponds during periods of heavy snowmelt, warm spring rains, or humid nights if there is no rain. The migration appears to be synchronized. Males court the females by nudging and rubbing them with their snouts. The male drops a spermatophore, which the female walks over and picks up with her cloacal lips. Males may drop nearly 100 spermatophores in a season. The breeding period lasts from a couple nights to over a week. The time varies by location. The females then lay from 1 to 200 eggs in a globular mass. The mass is attached to twigs or other underwater structures; very rarely they are laid on the bottom. The mass is covered with a jelly-like coating which may be clear or white. This prevents some predators from eating the eggs (Petranka 1998), but it is probably not the full function of the coating. The eggs hatch in only a few weeks. The larvae actively feed and grow for 2 to 4 months. The larval stage varies based on geographic location and water temperature. Some larvae are known to overwinter and transform the following spring (Phillips 1992).
Spotted salamanders spend a few years as terrestrial juveniles before becoming sexually mature. The terrestrial juvenile period may last from two to five years or longer. Transformed juveniles and adults spend nearly all of their time underground. They may be found under rocks, logs, or other debris especially during wet, damp, or humid conditions.
Spotted salamanders eat invertebrates such as earthworms and insects or anything else they can catch and swallow. Adults secrete a milky toxin from glands on the back and tail for defense against predation.