While hiking in the Blue Hills this fall, my friend Tim Beaulieu and I stopped to flip over a few logs along the side of a trail. As herpetologists — biologists who study reptiles and amphibians — our curiosity compelled us to see what might be hiding underneath.
Under the first log, we found a couple of red-backed salamanders, a common woodland salamander species. As Beaulieu was photographing the red-backs, I flipped over a second log a few feet away and was surprised to discover something I’ve never seen in suburban Boston: a red eft.
Red efts are the juvenile land-dwelling stage of the aquatic eastern newt. With a bright orangish-red color and red spots within black halos, these little salamanders look almost magical, like something out of Harry Potter’s menagerie. The sequence these amphibians go through on their journey from aquatic larvae to terrestrial red efts to adults that return to live in the water does border on magical.
When Beaulieu flipped a nearby third log, we saw this transformation firsthand, counting eight efts in various stages of development, their fading red color and emerging green color indicating they were metamorphosing into adult newts.
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There are six newt species in the United States, and over 60 species worldwide. The subspecies of eastern newt in Massachusetts is the red-spotted newt, said Jake Kubel, conservation biologist with the Massachusetts Division of Fisheries and Wildlife’s Natural Heritage and Endangered Species Program. They are common throughout the state, living in habitats like lakes, ponds, and slow-flowing rivers.
Newts like to hang out in aquatic vegetation, said Kubel, which provides good foraging habitat to ambush prey and gives newts an ideal place to hide their eggs, which they deposit one at a time in various locations over a period of several days. Newts breed in early spring in our region, but there is some fall breeding as well.
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The eggs hatch within about five weeks. The aquatic larvae are tiny — about a quarter of an inch long — with feathery gills. Over the next few months, newt larvae grow to about an inch long. They shed their gills in the fall and move onto land as red efts, Kubel explained.
Efts grow 2 to 3 inches long and typically remain on land for two to seven years, depending on the location, said Kubel. How long a newt remains in the red eft phase depends on things like food availability, climate, etc., which determine how fast efts grow and develop.
This year was not a good year for feeding and growth because of the drought, so they may remain efts longer, said Kubel. Hot, dry weather shuts them down. And the small insects, spiders, and mites they eat are not as active if it’s too dry.
Like other salamanders — and amphibians in general — efts need to remain moist to keep from drying out. After rainstorms, red efts often can be observed wandering around on the forest floor, sometimes in large numbers, said Kubel.
“When efts are on the move, they’re basically exploring other options,” said Kubel. “There’s competition for good spots to live and feed. Efts can be like nomads for periods of years seeking out new ground.”
After several years, red efts turn into green-colored adult newts with small red spots and return to live in the water. Some newts skip the red eft stage and transform directly from aquatic larvae to aquatic adults.
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“Coastal regions are more prone to populations that don’t include the red eft stage,” said Kubel. “Efts are less common in eastern Massachusetts than in the western part of the state.”
Scientists aren’t sure why, but it’s suspected that less favorable terrestrial habitat prompts newts to skip the red eft phase.
“It’s drier and warmer in eastern Massachusetts on average compared to areas like the Berkshires, so the eastern part of the state is not as favorable to red efts, which like moister habitats,” said Kubel.
Adult newts have toxic skin, but red efts have very toxic skin. The efts' bright colors, known as aposematic or warning colors, tell predators not to mess with them, Kubel explained.
The red spots on adult newts also may serve as warning colors, but some predators still eat them. While newts are toxic to most fish, they can be eaten by bullfrogs and snapping turtles without adverse effects, said Kubel. Leeches also will attack newts.
Kubel encourages people not to handle newts unless it’s necessary, and to wash their hands afterward.
Adult newts feed on aquatic organisms like amphibian larvae, salamander and frog eggs, and small fish. Preferred foods include aquatic snails and fingernail clams, said Kubel.
Red-spotted newts grow 4 to 5 inches long, and their life span from larvae through adulthood can be 10 to 15 years, said Kubel.
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Another interesting newt phenomenon is newt balls. In late winter just before ice-out, masses of newts are often observed writhing at the bottom of ponds, said Kubel. Newt balls could be related to breeding, but no one is sure why newts form these aggregations.
The biggest conservation issue around newts is the emergence of the salamander chytrid fungus as a potential threat to North American salamanders, said Kubel. Salamander chytrid came from Asia and is believed to have entered Europe through the pet trade. There’s a concern this fungus could get into North America and impact native salamander species. Research on the fungus is ongoing at UMass Boston and elsewhere.
“Red efts are highly vulnerable to chytrid,” said Kubel. “If it gets into Massachusetts, it could wipe out newt populations.”
Some 201 salamander species, including most Asian newts, have been banned from import, but there’s concern the fungus may already be here.
“Salamander chytrid has not been detected in North America in the wild yet,” said Kubel, “but based on statistics and shipments of Asian-sourced newts for pets, this fungus is likely in the US in someone’s home somewhere. If a pet newt escapes, the cat’s out of the bag.”
Don Lyman is a biologist, freelance science journalist, and hospital pharmacist who lives north of Boston. Send your questions about nature and wildlife in the suburbs to donlymannature@gmail.com.