Small, permanent ponds in woodland openings or in meadows with dense aquatic vegetations are preferred habitats for adult newts, although they are also often found in temporary ponds, the shallows of large lakes, quiet portions of streams, or other permanent or semipermanent bodies of unpolluted water. They have even been found at a depth of nearly 40 feet (12 m) in Lake George, New York (Conant & Collins 1991). The terrestrial efts are usually found in forested areas in the vicinity of breeding ponds, taking refuge under rotting logs, boards, rocks, and other natural and unnatural objects. They can withstand drier habitats than other woodland salamanders but are most active on the forest floor during and after rain when the substrate is moist and the temperature is above 13oC. At temperatures below 10oC they rarely appear even during very moist conditions. Thus, activity of efts is dependent on both temperature and rainfall (Healy 1973). Notophthalmus viridescens appears to be most abundant in temperate forests, though its range extends to subtropical Florida. It has been shown that, in species with broad geographical ranges, especially latitudinally, such as the Eastern Newt, there is geographic variation in temperature tolerance (Hutchinson 1961). Microhabitat temperatures may differ significantly from general temperatures; aquatic adults, especially those in deeper bodies of water, may experience considerably less diurnal and seasonal changes in ambient temperature compared to terrestrial efts due to the high heat capacity of water.
Adults of Notophthalmus viridescens feed on a variety of small aquatic invertebrates, including crustaceans (e.g. fairy shrimp, cladocerans, copepods), insect larvae (e.g. damelfly and dragonfly nymphs, mosquito and midge larvae), and mollusks (e.g. fingernail clams, snails). They also readily consume the eggs and larvae of other amphibians when available (e.g. eggs and tadpoles of wood frogs Rana sylvatica, eggs and larvae of Ambystoma) (Harding 1997, Gill 1978, Tyning 1990). Cannibalism on their own larvae has also been reported (Burton 1977). Larval newts feed largely on similar but smaller invertebrates as adults. The terrestrial efts forage on moist forest floors where they seek out insects, worms, snails, and other small animals of the leaf litter.
General availability of prey of the appropriate size and type seems to be a basic constraint on the diets of Eastern Newts, as in most amphibians. Analysis of stomach contents of the terrestrial eft stages of Notophthalmus viridescens in New York revealed that the abundance of food items in the stomachs was correlated with the relative prey abundance in the habitat (MacNamara 1977). Hamilton (1940) similarly found that larval newts feed upon small zooplanktons in direct ratio to their availability and accessibility and do not exercise any predilection for particular prey species. Seasonal differences in diets have been reported for adult Notophthalmus viridescens in New Hempshire, presumably reflecting seasonal availability of prey and the newt's opportunistic feeding habit (Burton 1977). Gill (1978) has similary noted seasonal changes in the diet of adult newts in Virginia. In late spring and summer, the newts apparently forage benthically and specialize on the fingernail clam Psidium which are abundant during that time; consumption of as many as 50 clams per adult per night had been observed.
Both visual and olfactory cues are important in prey detection (Duellman & Trueb 1994). Aquatic adults and larvae both use the hyobranchial apparatus to expand and contract the buccal cavity during feeding. Buccal expansion creates a negative pressure and generates an inward flow of water which sucks the prey into the mouth. Adults usually also lunge toward the prey prior to or simultaneously with buccal expansion (Duellman & Trueb 1994).
All life stages of Notophthalmus viridescens have toxic skin secretions that can protect them to varying degree from predators. The conspicuous terrestrial efts possess the greatest concentration of poison glands which produce very toxic and noxious secretions, including high concentrations of tetradotoxin, a neurotoxin and strong emetic (Brandon et al. 1974, Brodie et al. 1974 ). Their brilliant coloration -- orange-red dorsally and yellow-orange ventrally -- has long been regarded as aposematic, warning potential enemies of its unpalatability or toxicity and enabling them to forage or migrate diurnally. When attacked by a predator, usually a bird or a mammal, an eft may flex its mid-trunk so that the head and tail are raised and curled toward one another over the back, and become immbile (Brodie 1977, Brodie & Howard 1972). This stiff posture, referred to as the Unken reflex, exposes the bright ventral coloration, aiding in avoidance learning by visual predators as well as eliminating movements that could stimulate the predator to attack. The Unken reflex is exhibited in a number of terrestrial salamandrids for similar predator-deterring purpose, including the highly toxic Pacific coast newts in the closely related genus Taricha, which is 25 times as toxic per skin volume as the Notophthalmus eft (Brodie 1968).
The aquatic adults of Notophthalmus viridescens are considerably less toxic than the terrestrial efts; Brodie (1968) estimated the efts to be 10 times as toxic as the adults. Adults are nontheless avoided by some potential predators, such as certain predatory fish (Hulbert 1970). Dorsal skin of both eft and adult is more toxic than ventral skin (Brodie 1968). Toxicity of larval newts appears to be mild and not a deterrent to some predators. Larval Ambystoma opacum and predaceous insects of Odonata, Hemiptera and Coleoptera have all been observed to prey on larval newts (Gill 1978). Toxic skin secretion also does not protect adult or eft Eastern Newts with immunity from predation. Raccoons (Procyon lotor) have been found to consume efts without apparent toxicity (Hulbert 1970). Some whiptail lizards (Thamnophis sirtalis) show no ill effects after ingesting efts in the laboratory (Brodie 1968). Nevertheless, these occasional observations or laboratory force-feeding trials do not necessarily indicate that the predators can or will freely choose to feed consistently on newts; considering the energetic cost likely involved in detoxification, most predators would probably prefer not having to subsist on a diet of newts. Also, the emetic function of tetradotoxin and perhaps other compounds in skin secretions of these newts has as much selective value as toxicity, since efts that are retained by toads or snakes for up to 30 minutes and then regurgitated recovered rapidly without lasting ill effects (Brodie 1968).
Skin toxin of Notophthalmus viridescens, while effective in discouraging ingestion by larger predators, does not protect the newts from ectoparasites, the most important of which being the amphibian blood leech, Batrachobdella picta. A descriptive account by Gill (1978) illustrates the severity of leech infestation:
"...I observed many adults wandering in and out of the water throughout the breeding season. Temporary departure from the ponds in early summer appeared to be a behavioral mechanism of leech removal. Adult newts were severely attacked by amphibian blood leeches, Batrachobdella picta Verrill. Upon crawling out of the water, newts rubbed their bodies against vegetation and scraped the leeches off. Throughout May and June the infestation of newts by adult and young leeches was acute, and newts in the ponds were constantly biting and scraping thier bodies with their mouths and hind feet in vigorous efforts to remove the leeches. Through their ectoparasitism of adults, predation on larvae, and transmission of the blood endoparasite Trypanosoma diemyctyli, leeches are implicated as a major source of mortality in these populations of newts."
Because newt toxins are present only in their skin, animals like leeches that can penetrate into the body cavity can by-pass the line of defense and prey on newts without ill effects.
Adults of Notophthalmus viridescens are important predators in their aquatic community, especially in temporary ponds. They can persist dried ponds by hiding in moist mud and beneath plant debris, and when the ponds refill they are the first to enter the water column to feed on arriving or emerging aquatic prey (Hamilton 1941, Bishop 1941). In many temporary pond communities where fish are absent, Notophthalmus viridescens has been found to function as a keystone predator, capable of reversing the outcome of competitive interactions between its anuran prey species (Morin 1981, 1983, 1986). By selectively preying on the competitively superior species (e.g. Scaphiopus holbrooki and Bufo terrestris), Notophthalmus indirectly increases the abundance of inferior species (e.g. Hyla crucifer), which otherwise are excluded by interspecific competition. At high density, Notophthalmus is also capable of excluding a number of insect and amphibian species from temporary ponds by consuming all their eggs and larvae (Morin 1983). As a keystone predator, Notophthalmus viridescens appears to play an importance role in shaping species composition and maintaining species diversity in temporary pond communities.
INTRODUCTION | DISTRIBUTION | APPEARANCE | LIFE HISTORY | STATUS & CONSERVATION | REFERENCES | ONLINE RESOURCES | MUSEUMS
HABITAT
Small, permanent ponds in woodland openings or in meadows with dense aquatic vegetations are preferred habitats for adult newts, although they are also often found in temporary ponds, the shallows of large lakes, quiet portions of streams, or other permanent or semipermanent bodies of unpolluted water. They have even been found at a depth of nearly 40 feet (12 m) in Lake George, New York (Conant & Collins 1991). The terrestrial efts are usually found in forested areas in the vicinity of breeding ponds, taking refuge under rotting logs, boards, rocks, and other natural and unnatural objects. 
They can withstand drier habitats than other woodland salamanders but are most active on the forest floor during and after rain when the substrate is moist and the temperature is above 13oC. At temperatures below 10oC they rarely appear even during very moist conditions. Thus, activity of efts is dependent on both temperature and rainfall (Healy 1973).
Notophthalmus viridescens appears to be most abundant in temperate forests, though its range extends to subtropical Florida. It has been shown that, in species with broad geographical ranges, especially latitudinally, such as the Eastern Newt, there is geographic variation in temperature tolerance (Hutchinson 1961). Microhabitat temperatures may differ significantly from general temperatures; aquatic adults, especially those in deeper bodies of water, may experience considerably less diurnal and seasonal changes in ambient temperature compared to terrestrial efts due to the high heat capacity of water.
Adults of Notophthalmus viridescens feed on a variety of small aquatic invertebrates, including crustaceans (e.g. fairy shrimp, cladocerans, copepods), insect larvae (e.g. damelfly and dragonfly nymphs, mosquito and midge larvae), and mollusks (e.g. fingernail clams, snails). 
They also readily consume the eggs and larvae of other amphibians when available (e.g. eggs and tadpoles of wood frogs Rana sylvatica, eggs and larvae of Ambystoma) (Harding 1997, Gill 1978, Tyning 1990). Cannibalism on their own larvae has also been reported (Burton 1977). Larval newts feed largely on similar but smaller invertebrates as adults. The terrestrial efts forage on moist forest floors where they seek out insects, worms, snails, and other small animals of the leaf litter.
General availability of prey of the appropriate size and type seems to be a basic constraint on the diets of Eastern Newts, as in most amphibians. Analysis of stomach contents of the terrestrial eft stages of Notophthalmus viridescens in New York revealed that the abundance of food items in the stomachs was correlated with the relative prey abundance in the habitat (MacNamara 1977). Hamilton (1940) similarly found that larval newts feed upon small zooplanktons in direct ratio to their availability and accessibility and do not exercise any predilection for particular prey species. Seasonal differences in diets have been reported for adult Notophthalmus viridescens in New Hempshire, presumably reflecting seasonal availability of prey and the newt's opportunistic feeding habit (Burton 1977). Gill (1978) has similary noted seasonal changes in the diet of adult newts in Virginia. In late spring and summer, the newts apparently forage benthically and specialize on the fingernail clam Psidium which are abundant during that time; consumption of as many as 50 clams per adult per night had been observed.
All life stages of Notophthalmus viridescens have toxic skin secretions that can protect them to varying degree from predators. The conspicuous terrestrial efts possess the greatest concentration of poison glands which produce very toxic and noxious secretions, including high concentrations of tetradotoxin, a neurotoxin and strong emetic (Brandon et al. 1974, Brodie et al. 1974 ). Their brilliant coloration -- orange-red dorsally and yellow-orange ventrally -- has long been regarded as aposematic, warning potential enemies of its unpalatability or toxicity and enabling them to forage or migrate diurnally. 
When attacked by a predator, usually a bird or a mammal, an eft may flex its mid-trunk so that the head and tail are raised and curled toward one another over the back, and become immbile (Brodie 1977, Brodie & Howard 1972). This stiff posture, referred to as the Unken reflex, exposes the bright ventral coloration, aiding in avoidance learning by visual predators as well as eliminating movements that could stimulate the predator to attack. The Unken reflex is exhibited in a number of terrestrial salamandrids for similar predator-deterring purpose, including the highly toxic Pacific coast newts in the closely related genus Taricha, which is 25 times as toxic per skin volume as the Notophthalmus eft (Brodie 1968).
The aquatic adults of Notophthalmus viridescens are considerably less toxic than the terrestrial efts; Brodie (1968) estimated the efts to be 10 times as toxic as the adults. Adults are nontheless avoided by some potential predators, such as certain predatory fish (Hulbert 1970). Dorsal skin of both eft and adult is more toxic than ventral skin (Brodie 1968). Toxicity of larval newts appears to be mild and not a deterrent to some predators. Larval Ambystoma opacum and predaceous insects of Odonata, Hemiptera and Coleoptera have all been observed to prey on larval newts (Gill 1978). Toxic skin secretion also does not protect adult or eft Eastern Newts with immunity from predation. Raccoons (Procyon lotor) have been found to consume efts without apparent toxicity (Hulbert 1970). Some whiptail lizards (Thamnophis sirtalis) show no ill effects after ingesting efts in the laboratory (Brodie 1968). Nevertheless, these occasional observations or laboratory force-feeding trials do not necessarily indicate that the predators can or will freely choose to feed consistently on newts; considering the energetic cost likely involved in detoxification, most predators would probably prefer not having to subsist on a diet of newts. Also, the emetic function of tetradotoxin and perhaps other compounds in skin secretions of these newts has as much selective value as toxicity, since efts that are retained by toads or snakes for up to 30 minutes and then regurgitated recovered rapidly without lasting ill effects (Brodie 1968).
