Members of the family to which the blue-spotted salamander belongs, the Ambystomatidae, are commonly known as ‘mole salamanders’ due to their predominantly underground existence (5). However, unlike its close relatives, which are found below ground for most of the year (4), the adult blue-spotted salamander is often found under logs, leaf litter or rocks, although it does also use burrows, including those of other animals (2) (6). This species may sometimes be seen in the open during rain showers (2).
The diet of the adult blue-spotted salamander includes a wide variety of small invertebrates, including insects, earthworms, snails, slugs, spiders and centipedes. Blue-spotted salamander larvae also feed on a range of invertebrates, taking aquatic insects and small crustaceans, and are also known to eat tadpoles (6).
The skin of the adult blue-spotted salamander contains glands, particularly on the tail, which produce a whitish, noxious substance. If threatened, the salamander may raise and wave its tail, and if further provoked it may lash it to deter the potential predator (2) (4). This behaviour also serves to draw attention to the tail, which can be regenerated if it is damaged during an attack (4).
The blue-spotted salamander breeds from around March to April (2) (3) (4), or slightly later in northern parts of its range (6), with breeding often being triggered by warm evening rains or rapid snow melt (2). At this time, the adult salamanders migrate towards suitable breeding ponds and begin courtship. The male blue-spotted salamander courts the female by nudging her with his snout, before grasping her behind the front legs and rubbing his chin on her head. Eventually, the male releases the female and deposits a packet of sperm, known as a spermatophore, in front of her. The female then moves over the spermatophore and takes up the sperm (2).
The female blue-spotted salamander lays her gelatinous eggs in small clumps on sticks, rocks or other debris in the bottom of the breeding pond (2) (3) (6). Each clump typically contains up to a dozen or so eggs, and the female usually lays around 225 to 300 eggs in total during the breeding season (2) (4) (6).
The eggs of the blue-spotted salamander hatch in around 3 to 5 weeks, depending on the water temperature (2) (6), and newly hatched larvae measure about 0.8 to 1.2 centimetres in length (2). The larvae of the blue-spotted salamander face many predators, including diving beetles, newts and tiger salamander (Ambystoma tigrinum) larvae (4), but those that survive metamorphose into adults around two to three months after hatching, typically between June and September (4) (6). After spending a week or so hiding beneath logs and stones at the water’s edge, the young salamanders migrate into the surrounding forest (4). The blue-spotted salamander is thought to reach maturity in about two years (2) (6).
Intriguingly, all-female hybrid salamander populations resulting from mating between blue-spotted salamanders and Jefferson salamanders (A. jeffersonianum) are able to reproduce by parthenogenesis, without needing genetic material from a male. These hybrids do mate with males of one of the parent species, but the genes of the male are only occasionally incorporated into the offspring (4) (6).