Most amphibians spend at least part of their lives in water. High Park's wetlands have the potential to provide suitable habitat, but factors such as disturbance and over-abundant predators may be keeping population numbers low.
Frogs and Toads
There have been unofficial releases of green, leopard and bull frogs into High Park’s ponds and wetlands in recent years, but their populations may not have persisted.
The American toad (Anaxyrus americanus, formerly Bufo americanus), a terrestrial species that is more adaptable to urban conditions, breeds in the park’s wetlands and has recently become common. Their loud mating chorus can be heard in the spring.
Green frog (Rana clamitans) has also become common. Northern Leopard Frog (Rana pipiens) was known to be present in 1970s and may still be present due to releases.
by Kathleen Keefe
Deep in the damp and dimly lit ravine woodlands of High Park lives an illusive creature that doesn’t even have lungs! Instead, this amphibian breathes by absorbing oxygen through its wet skin. To survive, its skin must be kept moist so it can exchange oxygen and carbon dioxide much as we do when we inhale and exhale.
To protect its skin from drying out, this salamander must stay in the cool shaded hiding places offered by mature woodlands with lots of fallen logs, rotting stumps, forest debris and decaying leaf litter to protect it from drying out.
There are several reasons why most of us don’t see these secretive salamanders. First, they are slender-bodied and tiny, at birth smaller than a paperclip, as an adult rarely bigger than a French-fry. Second, they stay well hidden under damp debris where air and light cannot find them. Third, they are most active when it is dark and rainy and we’re inside. Finally, the High Park population of red-backed salamanders is not robust and is limited to just a few ravines. In a pristine ravine ecosystem where conditions are optimal, the red-backed salamanders often outnumber all the birds and mammals combined. When a ravine habitat is degraded, the salamander population becomes vulnerable.
Best Picnics Include Ants and Rain
Their overarching priority 24/7 is to avoid drying out, which would be fatal. This driving force determines when, where and what they eat. During and just after it rains, red-backed salamanders can safely crawl all over the wet forest floor among the leaves by day and on plants and trees by night hunting for a wide variety of invertebrates such as spiders, mites, centipedes, worms, millipedes, beetles, flies, larvae and ants. As the terrain begins to dry out, they must limit their foraging to the moist spaces between leaf layers on the ground. When even the leaves have dried out, the salamanders’ food options are further reduced to whatever they can find under rocks, logs or in animal burrows where food is apt to be scarce, but where moisture is sufficient to keep them alive. On very hot dry days, they retreat underground completely. They are able to endure periods of scarcity because when conditions are good, they feast and store extra reserves to draw on in lean times.
Territory for Two Based on Menu
In the summertime, each salamander lives on its own, rarely traveling further than a half meter in a day. Come fall, red-backed salamanders that have mates from the year before, find each other, re-establish their territory and defend it together. Fall is also when recently matured Red-backed salamanders choose their lifelong mates. To set courtship in motion, a newly matured male claims a small patch of forest floor and guards it aggressively. He marks the boundaries of the territory with his own droppings and secretions. When an unattached mature female comes along, she crushes the male’s droppings, inspects their contents and determines if her potential mate has a worthy territory based on the prey in his diet. She prefers ants because their exoskeletons are soft compared to other invertebrates.
If she is pleased by the contents of his fecal pellets, she enters the territory and the two of them defend it together by displaying threatening challenges and attacking invaders. The male takes on any other males that attempt to trespass, and the female opposes any female intruders. They both leave scent markings along the territory’s edges to communicate to others: their size, importance, identity, whether they are related, and the extent of their territory. Not all are engaged in this protective ritual of real estate. In fact, more than half of the red-backed salamanders are floaters without territories.
In winter, they all go below the frost line, seeking protection underground in small mammal dens and root hollows. When the snow melts in the spring, the salamanders come out of hibernation and males find and follow the scent of their mate’s pheromone trail. Some pairs mate in both fall and spring, but unlike other amphibians, red-backed salamanders do not need water to breed.
Mothers Devoted and Depleted
In late spring, females deposit clumps of eggs in desirable spots such as decaying stumps or hollow rotting logs. The greatest threat to the eggs is dehydration. Until they hatch, the mother keeps her own body curled around the eggs to protect them from drying out. During that eight-week period she eats only if and when prey happens across her path. Once the young emerge in August or September, the mother stays with the hatchlings for another few weeks. The physical toll of producing and protecting the eggs and young over ten weeks with very minimal nutrition means females are only able to reproduce every other year.
The Tail is not Always the End
It is assumed that red-backed salamanders have a 10 to 30-year life span like other salamander species. They have evolved ingenious survival tactics. In their very wet fungus-filled environment, it would be easy for disease-causing fungus to grow on their damp bodies. But Mother Nature to the rescue! Their skin produces a chemical that deters the growth of pathogenic fungus. Salamanders are hunted by mammals, birds and snakes, but when attacked, they can drop their tails to create a diversion while they escape. The tail grows back slowly, and the sacrifice is risky as the tail is the storehouse of nutrition in lean times.
A Vital Player in Ravine Health
Red-backed salamanders eat the invertebrates that feed on fungi, inextricably linking them to the quantity and diversity of ravine fungi from deep in the soil up to the top of the forest canopy. The healthier the salamander population, the healthier the fungal community that is responsible for breaking down organic matter and promoting the exchange of resources among the trees.
The steep slopes and moist bottomlands of the red-backed salamanders’ home in High Park ravines make this habitat extra vulnerable to damage. The creation of informal paths, intensified foot, dog and bike traffic, and the insurgence of invasive plants threaten the soil and deep root systems that stabilize the steep inclines and prevent erosion.
- Turtles in High Park
- Reptiles and Amphibians of Toronto, Toronto Biodiversity Booklet Series
- Ontario Reptile and Amphibian Atlas
- Table 3, Amphibians & Reptiles currently on record, 2002 (pdf). Excerpt from 2002 High Park Woodland & Savannah Management Plan.