Threats to Reptiles and Amphibians
Reptile populations have declined drastically in Ontario over the past century. The Ontario Endangered Species Act, 2007 considers 18 of the province’s 24 reptile species (75 percent) to be at risk. Fewer amphibian species are considered to be at risk, although amphibian populations are declining in parts of the province. Three species – timber rattlesnake, spring salamander and tiger salamander – have been extirpated.
To view the known ranges of all reptile and amphibian species in Ontario, click here.
Habitat loss and fragmentation
Habitat loss and fragmentation are the primary causes of the decline of reptiles and amphibians, both globally and in Ontario. In southwestern Ontario, urban sprawl and clearing of land for agriculture have caused the local extinction of many populations. Habitat destruction by off-road vehicles, such as ATVs, is especially problematic because the areas in which they are often used tend to be sensitive habitats, such as wetlands, shorelines and old dune habitats.
In Ontario, vehicles kill countless reptiles and amphibians on roads every year. Most of Ontario’s reptile and amphibian diversity occurs in southern Ontario, where road density is among the highest in Canada. It is now so extensive that no location in southern Ontario is more than a kilometre or two from the nearest road.
Ontario Road Network. Click to enlarge.
Because most roads are exposed to the sun and have gravel shoulders, they present excellent nesting conditions for turtles. In June, when turtles are looking for a place to lay their eggs, they are attracted to roads, and individuals may wander back and forth along a road for hours. Many are killed.
The concern with road mortality is not simply that animals are being killed, but rather that the mortality rate in many places is high enough to completely wipe out populations. This is especially true of Ontario’s turtles, which have long lifespans (over 70 years in some species) and low rates of reproduction. Consequently, the death of even a few individuals a year on roads will cause populations to decline, as they have sharply in Ontario. Seven of Ontario’s eight turtle species are already on the Species at Risk in Ontario list.
Road mortality is a threat to reptiles and amphibians even in our national and provincial parks. Algonquin Provincial Park, for example, has more kilometres of roads than the city of Toronto. A recent study found that rates of road mortality in a provincial and a national park in Ontario were as high as road mortality rates outside the parks.
Snakes are most affected by human persecution, which is likely caused by some common misconceptions. These are clarified below:
- The massasauga is the only venomous snake in the province. It has only ever killed two people, both of whom were bitten more than 40 years ago and both of whom did not receive any medical treatment after the bite.
- The massasauga’s primary defence is to remain motionless and unseen. Secondly, it will attempt an escape if possible. Generally, this snake bites only as a last resort and only after warning threats of its presence with its rattler. It will attack when, for example, people intentionally pick it up or accidently step on it.
- Many other snake species, even though harmless, act aggressively in an attempt to scare away predators. The most notable example is the hog-nosed snake, which flattens out its neck (like a cobra), rears up, hisses loudly and strikes with its mouth closed.
- The milksnake and eastern foxsnake vibrate their tail when something alarms them. This behaviour, combined with their blotchy coloration, fools many people into thinking they are rattlesnakes.
Wood turtle - a species at risk due largely to paoching
Illegal collection for the pet trade
Some reptile and amphibian species in Ontario are illegally collected and sold in the pet trade. A poacher can do significant damage to a population, since the species they target generally are already very rare. Consequently, details about the locations of rare species are closely guarded.
Pollution is a serious threat to amphibians, which have moist, absorptive skin that quickly takes up any toxins in the environment. Amphibian eggs lack the protective shell that bird and reptile eggs have, and are more susceptible to toxins in the environment. Furthermore, amphibians rely heavily on aquatic habitats, which are often polluted due to leaching, runoff or intentional dumping of chemicals into lakes and streams.