In today’s world, it’s pretty difficult to think of a species that scientists are not concerned about in the face of climate change. The reasons are many and diverse, but in a state where 42% of municipalities are considered “coastal”, it comes as no surprise that sea level rise (SLR) is a big threat here- both to people and wildlife. When the average person imagines which species are most likely to be impacted by SLR, it’s likely that beach nesters, including piping plovers, immediately come to mind. Afterall, they occupy the same environments that recreationalists are worried about losing. Valid point- but they are not the only ones. Eastern tiger salamanders, one of New Jersey’s rarest amphibians, also make the list.
Like our other mole salamanders (spotted, blue-spotted, marbled, and Jefferson), Eastern tiger salamanders require access to temporary wetlands, called vernal pools, to successfully breed. The ephemeral nature of these water bodies is critical because it eliminates fish as potential egg predators and thus increases larval survival. While these salamanders spend much of the year in forested landscapes, adults return annually to their natal pools (in most cases) to reproduce. High fidelity to these sites can put these amphibians in danger if development occurs within their migration corridors or changes transpire within the pools themselves.
Although I spend much of my time thinking about reptiles and amphibians, if you were to ask me if I could be classified as a “herper”, my immediate answer would be no. When I go for hikes, my objective is to reach the summit and take in the view- I’m not generally looking to offroad and go slow. I recently compiled a list, however, of all the herps that I have found during my outdoor adventures this year and was shocked to realize that I’ve encountered 31 species of wild turtles, snakes, frogs, and salamanders. Of those, I had the intention of locating 13 as part of my seasonal field assignments for CWF- the rest were all incidental finds. Moreover, despite the period in question being rather lengthy, it was very easy for me to parse apart which species were really 2023 observations versus some other year. And I can recall where I was and what the individual was doing in each case.
It’s always fun to learn the collective names for groups of animals. For example, in the amphibian and reptile world, we have an army of frogs; a congress of salamanders; a bale of turtles; and a lounge of lizards. I wonder what quippy term could describe a group of herpetologists- the folks who spend their lives studying the armies, congresses, bales, and lounges? Perhaps… a partnership?
In that case, a partnership of herpetologists from as far south as Virginia all the way up to Maine descended upon Middletown, Connecticut last month. Not to cross some rare species off their life list (though coincidentally, I crossed two off mine), but rather to attend the annual Northeast Partners in Amphibian and Reptile Conservation (NEPARC) conference, hosted at Wesleyan University.
CWF biologist, Christine Healy, holds a ribbon snake that was located during a NEPARC field trip along a powerline.
Complete the lyrics: Nothing else matters in the whole wide world when you’re in love with a…
If you said Jersey Girl, then you’d be correct! Coincidentally, that’s also where volunteers and supporters alike gathered last month to show their love for amphibians. Jersey Girl Brewing in Mount Olive, that is.
Two years ago, we partnered with Jersey Girl to host a trivia event to raise awareness for our Amphibian Crossing Project, an initiative that seeks to reduce mortality among populations of frogs and salamanders whose migratory pathways are bisected by roadways. We chose the location based on its proximity to our largest crossing site, Waterloo Road, in the hopes that many of our hardworking volunteers could attend. We had a great turnout and a lot of fun. Following several requests, we decided to bring it back this year for round two.
Participants, including former CWF intern, Nicole Bergen (who helped write and host our first trivia event) pause during answer deliberation to smile for the camera.
Lots of familiar faces were in the crowd at Jersey Girl, including CWF’s Founder, Linda Tesauro, trustees Steve Neumann, Rick Weiman, and Amy Greene, former amphibian crossing leads MacKenzie Hall and Allegra Mitchell, former CWF intern, Morgan Mark, and many new and seasoned volunteers, like Barb and Rick McKee, without whom, this project could not succeed.
If you follow us or any other wildlife organizations on social media, you may have noticed that our posts these last few days have been inundated with amphibians. It may seem like odd timing, given that our early breeders (wood frogs, spotted, and Jefferson salamanders) completed their crossroad migration last month. But the reason is simple – it’s Amphibian Week!
Close up of an American toad that hitched a ride during this year’s crossing. Photo Credit: Nikki Griffiths
Globally, amphibians are disappearing faster than any other vertebrate group. The International Union for the Conservation of Nature (IUCN) estimates that 41% of amphibian species categorized for their Red List are currently facing extinction. That estimate is likely conservative, given that these creatures are often small and difficult to survey, rendering many species data deficient. This is concerning from multiple perspectives. From an ethical standpoint, we don’t want any wildlife to go extinct except maybe, in my extremely biased opinion, certain types of ticks… (I began my career as a moose technician and saw firsthand the terrible consequences that winter ticks have on these behemoths). Beyond that though, amphibians are tasked with a lot of responsibilities and carry out their work efficiently and without complaint. The list is inexhaustive but here are a few things that amphibians are doing for us and our planet as we speak: filtering water, sequestering carbon, eating pests (like mosquitos!), serving as prey for countless predators, helping researchers study regeneration (with hopeful applications to the future of organ transplants), aerating the soil in your garden, indicating where water sources have been contaminated by pollutants, and giving everyone who meets them a reason to smile.
We’ve made it to the final “super species” in our “superhero” series though, like in the last post, we’re spotlighting an adaptation that aligns with one of the more notorious residents of Gotham City. Our local frog has all the chill, while this DC villain needs to chill… quite literally, as his sub-zero body temperature must be maintained to ensure his survival. Cryogenics expert, Dr. Victor Fries- better known as Mr. Freeze, had admirable intentions when he began his experimentation with ice. Unfortunately for him, accidental exposure to chemicals altered his physiology, necessitating the use of an air-conditioned suit and spurring a life of crime motivated by tragic desperation. The compound responsible for his transformation is thought by some to be glycerol, which also happens to be the key to the winter survival strategy of our favorite early breeding anuran- the wood frog (Lithobates sylvaticus).
Animals living in temperate climates must find ways to cope with the cold temperatures and reduction of food resources, characteristic of the winter season. Some species deal with winter by not dealing with winter… instead they migrate to milder conditions farther south. This is a path commonly taken by birds. Other animals have adapted to have a large body mass. This reduces their surface area and enables them to hold onto heat more efficiently. As a former moose biologist, I’m happy to give them a quick nod here. Many strategies exist across the natural world to increase the odds of persistence, but we’re here to talk about amphibians and, it’ll probably come as no surprise to you that they aren’t employing either of the aforementioned tactics.
Wood frogs are a vernal pool obligate species; they must have access to these temporary wetlands in order to breed and complete their lifecycle, but they don’t live in them all the time. Therefore, we do refer to them as migratory, but they only cover about ¼ to ½ mile during this annual pilgrimage, so temperature differences are negligible. Most frogs and salamanders in New Jersey endure the colder months by entering brumation- the “cold blooded” equivalent of hibernation. In this state, animals can drop their body temperature and metabolism to conserve energy. Some species burrow and use the ground as insulation. Others brumate in streams and ponds since water cools at a slower rate than air. Wood frogs cover themselves in leaf litter (for camouflage) and spend the winter comfortably as frog-cicles. That’s right- they essentially freeze solid and thaw once air temperatures become favorable again.
Under normal conditions, when a cell freezes, ice crystals form internally. These solids can then expand, which damages organelles and ultimately ruptures cell membranes. This leads to cell death. Compounded by damage incurred in blood vessels and dehydration, this would be a fatal situation for most animals. Wood frogs have found a hack to get around these devastating consequences.
A recently thawed wood frog huddled beneath a leaf. Photo credit: Nikki Griffiths.
As temperatures drop, wood frogs continue to produce urine but cease voiding it. Instead, the urine is concentrated into urea, which floods the frog’s bloodstream. The liver also goes into overdrive, manufacturing vast quantities of glucose, which causes their blood sugar to skyrocket as high as 100x normal levels (a better understanding of how this frog can avoid negative health effects under such conditions could certainly contribute to diabetes research in humans). The urea and glucose create a mixture that acts almost like antifreeze. Once ice crystals begin to form around the blood cells and internal organs, this homemade antifreeze infiltrates, allowing for the retention of water and protecting the frog’s cells from desiccation and explosion. They can maintain this state for up to 8 months.
This brumation strategy earns wood frogs the “northernmost amphibian in the western hemisphere” superlative as they can be found up past Gates of the Arctic National Park in Alaska.
The 2023 Amphibian season has begun! Drive carefully one upcoming rainy nights. Photo credit: Nikki Griffiths.
That’s a wrap on Mr. Freeze and our Super Species! The Amphibian Crossing is now in full swing. If you are going to be driving after sunset along roads that border ponds in the upcoming rains, watch out for migrating frogs and salamanders. Collisions with motor vehicles can decimate local populations rapidly so please slowdown!
This post is the second in our “super salamander (and frog)” series in which we’re exploring some of the unique adaptations exhibited by local amphibians that would seem more appropriate within the confines of a comic book than out and about in our Garden State landscape. Today’s focal species is the spotted salamander (Ambystoma maculatum), our benevolent Poison Ivy. Full disclosure, this topic has nothing to do with plant, though salamanders themselves are not sensitive to the compounds that make humans itchy and have been known to use “leaves of three” as sources of shelter.
For those of you who may be unfamiliar with the DC Comic Universe, Poison Ivy is a villain who often opposes Batman (and occasionally Superman) during her crusade to protect plants and rid the world of environmental destruction. Though her goals may seem in line with ours here at CWF, her methodology differs dramatically and she is often defined as an eco-terrorist. A former botanist, Poison Ivy, AKA Pamela Isley, was poisoned by her professor. Though she survived the experience, the toxins drove her insane and transformed her into a human-plant hybrid. And that is where our connection lies…
If you’ve ever seen an egg mass deposited by a spotted salamander, you may have noticed that the casing often appears green. This is caused by an association with a very particular kind of green algae called Oophilia amblystomatis. The connection between salamanders and algae has been recognized for > 130 years. For most of that time, it was thought that the algae just occurred within the egg. This is a sensible mutualism- it is auspicious to both species involved. Spotted salamander eggs develop in vernal pools. These temporary wetlands may have relatively low concentrations of dissolved oxygen, so the introduction of algae, which can create oxygen through photosynthesis, into eggs can certainly benefit growing larvae. Under experimental conditions where salamander eggs containing algae were cut off from sunlight, growth and development was delayed and resulting individuals were smaller than those exposed to natural circumstances. On the other side, larvae produce CO2 and nitrogenous wastes, which can be used to the advantage of the algae. Studies have shown that Oophilia are most successful in water that has been exposed to spotted salamander eggs, even if they are not within the eggs themselves. Case closed, right?
Developing spotted salamander larva with Oophilia algae. (C) R. Hangarter
Wrong. In 2011, a team of researchers at Dalhousie University in Halifax, Nova Scotia, discovered that the relationship between these two organisms is, literally, skin deep… The algae don’t just infiltrate the salamander’s egg masses. They are also found within the salamander’s tissue cells. This type of connection is called an endosymbiosis- one cell living inside another cell. Coral reefs and their associated algae are the poster children for this phenomenon, but it is not uncommon among invertebrates. Vertebrates, however, tend to have much more active immune systems that are programed to recognize a cell growing within another cell as a health threat. We can be grateful for that, as dangerous pathogens (e.g., malaria), can spread this way. In the case of salamanders and algae, the above-mentioned team discovered that the amphibians were actively suppressing their immune systems to allow for the success of the algae, which indicates that they must continue to benefit from this association. The algae show signs of stress when encapsulated within the body of salamanders; sunlight becomes harder to access, so rather than creating energy through photosynthesis, they switch to the process of fermentation.
The endosymbiotic mutualism between spotted salamanders and green algae is totally unique among vertebrates. No other amphibians, reptiles, mammals, birds, or bony fish are known to support a similar relationship. Research on the mechanisms and the meanings of this “partnership” are ongoing, but scientists are hopeful that the discovery could yield novel techniques for medical advancement.
While spotted salamanders are certainly not hybridizing with their algal associates, in a way, they walk the animal-plant boundary as they incorporate both types of cells within one compact package, therefore making them the amphibious analogs of DC’s Poison Ivy.
Spotted salamander crossed during the 2022 migration.
Our final installment will shift the focus to frogs and, in particular, one that doesn’t mind the late winter chill…
I felt confident, after the mild conditions that we experienced in January and much of February, that March would skip the “lion” phase of the well-known adage and come in and out like a lamb. I was clearly incorrect…
In anticipation of the amphibian migration, I thought it would be fun to write about some of the most unique adaptations displayed by three early-breeding vernal pool obligates that we target during our Crossing program. These species require access to temporary wetlands in order to complete their life cycles and are thus at greater risk of motor vehicle collisions than other amphibians that don’t rely on these resources. As I started drafting this, I kept thinking about parallels between the behaviors that I chose for each species and superheroes/villains whose background and abilities relate. And so, I’m kicking off this series with our very own Wonder Woman, the Jefferson Salamander.
Every January, once the confetti has settled from the new year’s celebration, I start thinking a lot about amphibians and preparing for their springtime migration. That behavior, however, is not collectively adopted by all of our local frogs and salamanders. Different species have found different ways to adapt to the challenges of a complex lifecycle that relies on environmental factors to inform physiological changes. Wood frogs, as well as spotted and Jefferson salamanders, have conformed to an early spring breeding strategy. Once the ground thaws and snow melt has raised the water level in vernal pools, they are on the move. Since amphibians in temperate climates hibernate (or more correctly, brumate – the “cold-blooded” equivalent), you might think that their appearance in February and March means that they lead the pack. While this seems a reasonable assumption, it’s actually incorrect.
According to an old English proverb, good children should be seen and not heard. If that’s the case, salamanders could be thought of as the epitome of obedience- rarely uttering a sound (though some species are capable, including mole salamanders and newts) and often visible only during migration events or chance encounters along hiking trails. Because they don’t command our attention in the way that flashy birds and charismatic mammals do, they may be easily overlooked. Indeed, amphibians are one of the least studied classes of vertebrates- and the most threatened, with 41% currently facing extinction. Though staggering, that statistic is likely quite conservative as almost a quarter of species known to science are considered data deficient by the International Union for the Conservation of Nature (IUCN). This is concerning- not only for supporters of the intrinsic value of wildlife- but also from a practical standpoint…
A 1975 study conducted in Hubbard Brook Experimental Forest, NH, estimated that an average of 2,950 salamanders of five species (primarily red-backed) occurred across each hectare of the site. Using this figure, they calculated the total weight, or biomass, of salamanders and found it to be roughly equivalent to all small mammals and > 2x that of birds present during peak breeding season. Extremely high densities and biomass place a surprising amount of power and responsibility on the shoulders of these small creatures.
