Little Bog of Horrors

I find the urge to explore bogs and boggy habitats difficult to resist. Other people avoid them, which gives me space to be alone. They’re mucky, which is often a fun and challenging substrate underfoot. They contain unique species, which I find fascinating. They are full of life. And they offer surprises.

On an unseasonably warm late October day, I found myself poking around the edges of Little Messer Pond, an approximately 27-acre pond in Katahdin Woods and Waters National Monument, Maine.

Photo of pond and surrounding vegetation. Pond is at lower right. Short shrubs and sedge at lower left. Pines, spruce, and large line pond.
Little Messer Pond
Photo of pond. Trees line the pond in the middle and background. Short shrubs form the pond's border in the foreground.
Little Messer Pond

While exploring the pond’s northern flank, on a shelf of sphagnum peat that cups the pond’s shore, I found several purple pitcher plants (Sarracenia purpurea), one of the most iconic bog species in this area. The purple pitcher lives an uncommon, carnivorous lifestyle for a photosynthesizing organism. Pitcher plants supplement their growth by capturing small animal prey, typically insects. Unlike Venus fly-traps, however, which ensnare prey using a trigger-like mechanism, pitcher plants use a passive, gravity-driven process. Their leaves form bell or cone-shaped bowls that fill with rainwater. The top of the each leaf has a flaring lip lined with nectar glands to attract insects. If a hapless insect falls inside, downward pointing hairs resist its escape attempts. 

Several pitcher plants growing out of reddish-colored sphagnum moss.
Purple Pitcher Plant

Pitcher plants can’t move, so they have unsurprisingly indiscriminate tastes. To cite just one example, a study from Newfoundland documented 12 insect orders serving as prey in pitcher plants. Prey eventually drowns in the pitcher’s water where enzymes as well as inquilines (microorganisms adapted to live in the pitchers such as midge larvae, nematodes, bacteria, protozoa, and rotifers among others) break down the trapped prey, releasing nitrogen and phosphorus for the plant. Purple pitcher plants, in particular, seem to be particularly rich in inquilines, hosting at least 165 different species across its range. Pitchers are habitats of their own making and their adaptations allow them to live in nutrient poor soils where competition from tall plants in minimal.

Looking at the pitchers on the edge of Little Messer, I found ants, beetles, flies, dragonflies, various bits of unidentified insects, and a sludge of the leftovers in their bowls.

They’d eat me if I were small enough. 

GIF from Little Shop of Horrors. Plant says "Feed Me!" while Seymour looks at it.

None of the prey was unusual or unexpected until I stumbled upon a curious sight—a spotted salamander inside a pitcher.

Spotted salamander floating in a pitcher plant's bowl.

I was taken aback by the sight. I had never seen something like this before, and I remember exclaiming “What the?” even though I was alone. Was this a big payday for the plant or was the salamander only a temporary resident?

Small vertebrates are exceedingly scarce as a prey item for purple pitcher plants. In the scientific literature, I couldn’t find much documentation of it. A study from Massachusetts documented red-spotted newts as a food source for pitcher plants. A more recent study from an Ontario bog found that spotted salamanders are a potentially rich prey for pitcher plants. (One of the researchers leading that study described his sighting of a salamander in a pitcher plant felt like a “WTF moment” so I guess I wasn’t alone in my surprise.) In August 2017, researchers at that study site searched the contents of 144 pitcher plants. They found, as expected, mostly insects but also several recently metamorphosed spotted salamanders. In August 2018, they investigated 58 plants and found three spotted salamanders. The physical condition of the salamanders varied. Some were in an advanced state of decay while others were lively and were able to swim to the bottom of the pitcher when disturbed.

Plenty of uncertainty surrounds pitcher plants and the importance of small vertebrate prey to them like salamanders and newts. No one has yet tested what might attract a salamander into a pitcher since a salamander has to climb up to get into one. If the salamander can escape, then pitchers could be a refuge for salamanders who have recently emerged from the water onto the land. Perhaps salamanders are attracted to the pitcher by small insects visiting to feed on the plant’s nectaries. Their apparent capture could be random too, although, dead salamanders apparently break down quickly inside pitcher plants so maybe their true rate of capture is greater than anyone realizes.

I wonder if it might happen only in places with the right combination of habitats. Purple pitcher plants typically (but not exclusively) grow in nutrient poor bogs, places that don’t always support breeding populations of spotted salamanders. Adult spotted salamanders migrate en masse during spring to vernal pools where they breed. They may also use permanent ponds for reproduction as long as those don’t contain fish, which eat salamander eggs and larval salamanders. Newts, in contrast, breed in a greater variety of wetlands including ponds and lakes that contain fish. 

At the Ontario study site, pitcher plants grow on bog islands in permanent and fish free ponds where spotted salamanders gather to breed every spring. This seems to provide a combination of habitats that increase the likelihood of pitcher plants capturing salamanders later in the year when the juvenile salamanders metamorphose and begin their terrestrial lives. Little Messer Pond, in contrast, is home to fish, snapping turtles, and presumably other salamander predators.

A salamander or newt, even a juvenile, is a significant catch for a pitcher plant. A newt of about 500 mg of dry mass contains about 5 mg of nitrogen, which is several orders of magnitude more than an ant, a pitcher’s most common prey. That’s enough nitrogen to increase the probability of the plant flowering the next summer. If the salamander I saw had indeed perished in the pitcher, maybe it’ll dignified in death by a marvelous pitcher plant flower next summer.

Pitcher plant flower. Petals are fleshy. Flower is radially symmetrical.
In my area, purple pitcher plants flowers appear in early summer.

Pitcher plants are wonderfully adapted to secure nutrients and survive in habitats that most plants cannot tolerate. If they’re lucky enough to capture something as large and nutrient rich as a salamander, then their physical structure can hinder escape. Their acidic water (often lower than pH 4 by mid summer) can weaken salamanders through electrolyte imbalance. And, the water within them might contain compounds that inebriate or paralyze small prey. 

The fate of the salamander that I found remains unknown. I returned a week later with the intention of relocating it, but I could not find it despite my best efforts. Although I can’t be sure, I think it is unlikely that I missed it since the boggy area with the pitcher plants isn’t large and the pitchers are easy to locate. If it were still alive, perhaps it fled to the bottom of the pitcher upon my approach. However, if it were still in the pitcher after seven days, then it should’ve been dead. Did it escape the trap that so many other victims of pitcher plants could not? I wish I knew the end of this story—a drama of uncertainty, survival, life, and death.

A Big Night for Amphibians

In many ways winter is a glorious season. There’s nothing quite like the silence of the forest during a winter storm, when the landscape is remade under falling snow. During March, however, when snow has cloaked the land for months and summer seems a distant memory, I begin to dream of greener pastures, so to speak.

I’m not the only one who feels the pull of spring. For many animals, spring is not only a season of renewal but also one of frenzied business. Perhaps nothing symbolizes the end of winter in the northeast U.S. like the return of the amphibians.

close up view of spotted salamander crawling through grass. photo taken at eye level with salamander.
Spotted salamander.

Amphibians in the northeast U.S. lead relatively inconspicuous lives. During summer, I’m lucky to see a handful of spring peepers as I tromp through the forest or poke around my garden. Toads make their rounds, yet are camouflaged well enough to typically escape detection unless they hop. I might spot some bull and green frogs lurking on the edge of a pond, eyeing me warily, but I hear them calling far more often then I see them. Except for the boldly colored red efts or eastern newts, I typically don’t see salamanders unless I search the undersides of down logs, and I won’t see the more fossorial of salamanders, such as the spotted salamander, at all when they inhabit their burrows.

During winter, amphibians are even harder to come by. Tucked within the forest duff, wood frogs and spring peepers survive winter frozen like a popsicle (and I mean, actually frozen, not just cold). Adult newts remain hidden under the ice of their home pond. Spotted salamanders undergo their own form of hibernation in burrows they’ve appropriated from other animals.

Winter is often loath to end in Maine and the thaw usually progresses in spurts. In March or April, the warm days begin to outnumber the subfreezing. Meltwater and perhaps a cool drizzle percolates through crusty snow to the forest floor. Eventually, a storm front pushes through bringing overnight rain instead of snow. If the ground is mostly snow free and the rain coincides with temperatures above 40˚ F, I know it’s time to don my trusty yellow rain slicker and rubber boots for a walk in the dark. The mass amphibian migration nicknamed the Big Night has arrived.

close up view of spotted salamander. photo taken at eye level with salamander.
“Feeling cute. Might delete later,” says this spotted salamander.

Early spring this year brought unusually dry and warm weather in my region. The two plus feet of snowpack that lingered into mid March disappeared rapidly, but no rain came until April 10. That evening, right around 8 p.m., a light drizzle began to fall. Although I was unsure if it would be enough to initiate the amphibian migration, I only walked a few hundred yards along my road before I found out.

On the broken pavement, headed north to a small pond, sat a wood frog. Soon after, I found a spring peeper and then a gray tree frog. The amphibians were certainly on the move.

Wood frog.
overhead look at spring peeper on road
Spring peeper.
close up look of gray tree frog. photo is taken at eye level with frog.
Gray tree frog.

Activity along the next half mile of road was unsurprisingly sparse as it descended through forest without any close-by vernal pools or ponds. The next hillside, however, brought me through a true hotspot. I could hardly walk 50 feet without finding one or more spotted salamanders on the road.

close up view
A spotted salamander glares at me as it crosses the road.
close up view of blue-spotted salamander. Head is at center and facing right.
Blue-spotted and Jefferson’s salamander form a hybrid complex in Maine. This fine specimen I found is likely a hybrid.

While the frogs I had seen earlier live above ground during the active months, spotted salamanders live the majority of their lives underground or at least hidden under leaf litter, a lifestyle typical of the “mole salamanders” in the genus Ambystoma. They are conspicuous only during their brief breeding period in spring. Spotted salamanders return to reproduce in the same pond or vernal pool where they were spawned only to leave the water and return to their mole-like habits a few days later.

For me, a fellow who is increasingly interested in all critters small, the Big Night is one of the best evenings of the year. For the critters I seek, though, the Big Night can be one of the most dangerous experiences of their lives. Many do not survive their attempt to cross the road.

For wildlife, roads and motor vehicles are one of humanity’s most hazardous inventions. Although estimates vary widely, we probably kill hundreds of millions of vertebrate animals (and maybe even as many as one billion animals) on roads in the U.S. every year. This includes somewhere between 89 and 340 million birds. In 2015-2016, according to State Farm, 1.3 million collisions with large mammals cause enough vehicle damage for drivers to file insurance claims. Pennsylvania drivers led the charge with more than 133,000 wildlife-collision insurance claims. (I grew up and learned to drive in Pennsylvania and have unfortunately experienced more than one collision with deer. I’m not sure I have any family members in PA who haven’t struck deer in a car. Yay for the Keystone State.)

Since small animals like salamanders and frogs don’t cause vehicle damage, their road-caused mortality seems to be poorly quantified compared to large animals. A study from Massachusetts, though, found that motor vehicles are significant source of mortality for individual spotted salamanders and could lead to population extirpation if road mortality reached 20-30 percent of a population. Near prime breeding habitat, a Big Night migration can bring hundreds of amphibians onto roadways per hour. Afterward, when juvenile and adult amphibians disperse from their aquatic breeding habitat, road mortality can also be significant. However, dispersal from breeding ponds is more diffuse in time and space than the initial migration, and we know even less about road mortality during that phase of their lives.

Amphibians aren’t random users of the landscape. They seek out particular habitats. Spotted salamanders, for example, generally breed in the same water bodies where they were born. The collective migration to breeding ponds can funnel many individuals into a small area. This is where data gathering becomes an important conservation tool, especially if we are to lessen their risk of becoming road kill.

On April 10, I walked about three miles between 8 and 11 p.m. (the Big Night isn’t a fitness walk), but more than half of the salamanders I saw crossed the road within a single 100-yard stretch. On April 17, with just the barest spittle of rain falling, I walked the same road and saw no amphibians on it except within the same 100-yard section.

Google Earth image with yellow pins concentrated at center of image. Roadway
In this Google Earth image the yellow pins mark a concentrated area of spotted salamander sightings on April 10, 2021. A small pond at bottom-center is the salamanders’ destination. The mature forest north of the road offers salamanders good habitat the rest of the year.

I’m fortunate to live along a quiet, rural road where traffic is light even on the busiest days. During my Big Night walks, I may only see three or four cars at most. Still, I find road kill salamanders. So, removing live amphibians from the roadway (in the direction they are headed, of course) gets them out of harms way.

One great thing about the Big Night is that it provides a valid excuse to handle frogs and salamanders. Gently moving them from the traffic lanes can help ensure they don’t become pancakes under car tires.

Road hazards for wildlife is an issue that needs more attention from our policy makers and highway departments. To address it, we need, like so many things, systemic change. Road design must consider the safety of the most vulnerable—such as pedestrians, cyclists, and wildlife—before the convenience of motorists.

Individually, we can help by joining community science efforts such as the Big Night to document amphibian migrations and amphibian road mortality. We can also drive less, drive slower, and avoid driving at night when possible. Perhaps you might even be able to convince your town to temporally close roads during springtime amphibian migrations or build structures to guide amphibians under roads safely.

Amphibians bridge the aquatic and terrestrial worlds. They hail from an era in Earth’s history when vertebrates had yet to thoroughly colonize the continents. Their longevity as a taxonomic order (amphibians first appeared more than 350 million years ago) underscores that the strategy works. Yet, amphibians face increasingly dire challenges due to roads, disease, habitat loss, non-native species, the exotic wildlife trade, and climate change. Collectively, amphibians are the most threatened group of animals on the planet. Since we are the collective cause of these threats, then we owe it to amphibians to correct them.

The Big Night represents the transition between winter dormancy and the frenzied attempts of many amphibians to reproduce. Before documenting their migration across my road during the past two years, I had no idea that most spotted salamanders funneled to and crossed it along a single 100-yard long section. Searching for amphibians along roadways has helped me better understand their lives and their vulnerabilities in an increasingly human-dominated world.