by Christine Healy, Wildlife Biologist
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.
Trophic Regulation: Perhaps the most intuitive ecosystem function of salamanders (and their eggs) is as prey. These animals provide protein-rich snacks for a diversity of other species including birds, rodents, raccoons, skunks, reptiles, frogs, and fish, among others. But their importance in the food chain does not end there; salamanders are actually the most dominate vertebrate predator within forested and vernal pool ecosystems. Members of the plethodontidae family (lungless salamanders) are credited with the regulation of terrestrial invertebrates, while species within ambystomatidae (mole salamanders) provide the same function within temporarily aquatic landscapes. The dietary preferences of these amphibians can effectively regulate the diversity of insect populations. This can provide an important service to humans; One study found that mosquito populations were 98% lower around ephemeral water bodies containing salamanders compared to those without. In addition to increasing the comfort of living and recreating around these features, by reducing mosquito populations through consumption or by deterring females from depositing their eggs, salamanders can limit the spread of diseases, like malaria, for which these insects are vectors.
Carbon Sequestration: The impact of a salamander’s diet extends farther still; insects feed in a variety of different ways, or functional groups. One such group, the shredders, attain nourishment by breaking down leaf litter into smaller components. By doing this, they expedite the decomposition process. Decomposition releases carbon dioxide as a byproduct, so the activity of shredders contributes to the speed and quantity of gas which enters the atmosphere. Salamanders eat vast quantities of shredders that are active on the forest floor, which reduces the breakdown of organic matter (by an estimated 11-17%, according to one paper) and allows the soil to act as a carbon sink. This role in carbon sequestration becomes even more important as the impacts of global climate change increase in severity.
Soil Dynamics: One reason that salamanders are rarely seen is that they commonly spend a significant portion of their lives underground. Sometimes they will take advantage of existing tunnel systems, constructed by small mammals, however, many species are capable of excavation themselves. These channels serve to reduce compaction and aerate the soil. Aerated soil presents fewer obstacles to expanding root systems and increases the availability of oxygen which can help to replenish soil nutrients. Their role in soil dynamics renders these vertebrates friend to foresters and gardeners alike.
Indicators of Ecosystem Health: Amphibian skin is porous and covered in glands that secrete mucus and toxins, which enable them to carryout their daily activities. While this provides limited protection from injury and external stressors, it enables salamanders to assume adaptations that would be unavailable otherwise. Many adult salamander species breathe directly through their skin, which may reduce their buoyancy and prevent them from being swept away in strong currents. The tradeoff, however, is that amphibians are therefore highly sensitive to contaminants within their environment. An absence of salamanders in locations where they would normally be expected can serve as a proxy for ecosystem health and can help humans determine where water may be impaired or polluted.
Salamanders serve several important roles in keeping temperate landscapes functional and balanced. Some of these contribute to supporting (decomposition, nutrient cycling) and regulating (pest control) ecosystem services that directly or indirectly benefit people. They can also provide additional services that are unrelated to ecosystem health.
Key to Medical Advancement: Salamanders are something of a medical marvel. Lizards are recognized for their caudal autonomy; the ability to drop and regrow their tails when threatened. Salamanders can do that… but they can also reform limbs and even parts of their internal organs. This ability, which is unique among vertebrates, could eventually make lab-grown organs a reality for transplant patients.
Creatures of Fire: Salamanders, additionally, hold a cultural value. They’ve appeared in religious and philosophical texts, folklore, and mythology for hundreds of years; sometimes villainized, sometimes revered. I’ll save that discussion for another day…
Though you may think of salamanders infrequently due to their shy and secretive nature, they’re out there, wearing many hats, and working hard to keep our environment in check. Whether or not they can continue that necessary work, however, is up to us. Want to help your new favorite Renaissance (sala)men? There is plenty that you can do right at home:
- Make your yard friendly to amphibians by leaving piles of leaves and wood accessible for them to use as shelter.
- Disinfect your boots between hikes, particularly if you’ve been walking through streams! Amphibians are highly impacted by fungal pathogens that can be spread this way.
- Never remove animals from the wild OR adopt pets whose origins you are not completely sure of. The illegal pet trade contributes to species listings. They are happiest where they are.
- Don’t handle amphibians unless you are moving them off a roadway. The oils and chemicals on our hands can clog pores and damage their skin.
- Educate your friends and family on how awesome and important these animals are! People care when they are in the know.
- Donate to support our work to protect salamanders and other amphibians at www.conservewildlifenj.org/getinvolved/donate/ or mail a check to Conserve Wildlife Foundation, 2 Preservation Place, Princeton, NJ 08540. Please and specify “Amphibian Project.”
- The migration season is nearly upon us! If you are driving between a body of fresh water and a forest at night in the spring and it is raining- slow down and stay alert! Roads often separate necessary components of amphibian habitat, forcing them into dangerous situations. Road mortality can decimate populations in just a few years.
Tags: ambystomatidae, Carbon Sequestration, Conserve Wildlife Foundation of New Jersey, ecosystem functions, Ecosystem Health, lungless salamanders, Mole salamanders, New Jersey, newts, plethodontidae, Salamander crossing, salamanders, Shredders, Soil Dynamics, Trophic Regulation, wildlife
Great article with a lot of good information! We humans, who receive so much benefit from wildlife and yet have caused so much habitat and species loss, need to act now to help all endangered species large and small!