The Eastern Newt (Notophthalmus viridescens) is a common species of newt found throughout eastern North America. Eastern newts are a member of the family Salamandridae, and one of only two genera endemic to North America. Four varieties of N. viridescens are currently recognized in North America: the red-spotted newt (Notophthalmus viridescens viridescens), the peninsula newt (Notophthalmus viridescens piaropicola), the central newt (Notophthalmus viridescens louisianensis), and the broken-striped newt (Notophthalmus viridescens dorsalis). Although there are notable differences in size and appearance of the newts of these four groups, studies of their DNA have revealed that little genetic variation exists between them, so they are not considered true subspecies. This article will focus primarily on Notophthalmus viridescens viridescens.
The red-spotted newt is the largest of the four varieties. These newts have three specific life stages: aquatic larva, terrestrial juvenile, and adult. The aquatic larvae typically range from 7 to 9mm in length when they hatch, with gills and a laterally compressed tail that support survival in their aquatic environment. At approximately 3 to 5 months, they metamorphose into their terrestrial juvenile stage. Newts in this stage are referred to as “red efts”. These efts range in color from orange to bright red. They have two parallel rows of up to 21 red spots with black outlines. Their skin is dry and textured, they have resorbed their gills and caudal fin, and they have developed lungs, eyelids, and limbs to support their new terrestrial lives. After 2 to 3 years, the juveniles then metamorphose once more, this time into sexually mature adults. At this stage, a newt can grow up to 5.5” in length and are identified by their greenish- to yellow-ish brown dorsum with rows of orange to red spots running down both sides of their back. The ventral surface is yellow with small black spots that fleck the skin. The skin is moist, and most adults return to aquatic environments.
Diet/Feeding: Red-spotted newts feed on small invertebrates, including worms, insects, small fish, amphibian eggs, etc.
Habitat/Range: The collective range of all four regional varieties extend from the Maritime Provinces of Canada to as far south as Florida, and west to Texas and the Great Lakes. Larval newts occupy small freshwater environments, such as ponds or small lakes. Efts move to moist terrestrial areas surrounding these bodies of water. While the majority of adults return to a fully aquatic stage, some adults can move back to land if dry conditions exist.
Reproduction: Adult newts return to permanent or semi-permanent bodies of water for breeding, which takes place in late winter and spring months. This migration is usually preceded by heavy, seasonal rains. Males are easily recognized by their enlarged hind limbs, nuptial excrescences, swollen cloaca, and crested caudal fin during the breeding season. The male lures the female by fanning his tail, then grasps the female and rubs his genial gland (found in the temporal region) along the female’s face. If the female is receptive, the male will deposit a sperm packet on the pond floor, which the female will then pick up via the cloaca. After they are fertilized, the female will singly lay between 200 and 400 eggs on vegetation in the water over a period of many days.
Herping Tips: Red efts and terrestrial adults can be found under rocks and in leaf litter on the forest floor, typically within close proximity to a source of water. During the spring months, shallow ponds that lack the presence of large predatory fish can host an abundance of breeding adults. Because these adults must breathe air, they can often be observed swimming along the surface of the water. Many amphibians, including the red-spotted newt, will exhibit the unken reflex when startled. The unken reflex is the defensive posture pictured below, in which the newt arches its body to reveal its brightly colored ventral surface as a warning of toxicity to potential predators.