Frogs on the road
By Jim Poling
Published May 18, 2017
Sloughs, marshes and ditches along the roads are brimming and finally getting some warm sun. So it won’t be long now before thousands of amphibians begin their annual overland migrations.
It usually happens on warm rainy nights in late spring or early summer. Young frogs and toads and other amphibians move out of their watery homes in search of land nesting sites.
They often cross roads in swarms of hundreds or even thousands during the migration. There was a report last year of as many as 1,800 toads an hour crossing a beach trail in British Columbia.
Frogs and toads start life in the water as spawn. They metamorphose into tadpoles (or pollywogs) and learn to swim. They metamorphose again into tiny frogs or toads. Then they leave the water in huge migrations seeking damp land nesting areas. Once they mature to breeding age, they migrate back to water to lay their own spawn.
Migrations that move onto roads present a problem for the amphibians, as well as motorists. Some years back I was driving Highway 117 on a warm, wet night when I came out of a curve and saw a mass of tiny frogs moving across the pavement. The choice was to hit the brakes and steer toward the road shoulder or carry on, squishing dozens of frogs beneath the tires.
That incident illustrates once again the clash between human activities and nature. Road safety is a paramount concern, but we all must be more aware of the dangers we present to nature and continually look for ways to protect it.
Tens of thousands of amphibians and reptiles are killed annually by vehicles on Ontario roads. Many of these are at-risk species such as the Massasauga rattlesnake, found mainly in the Bruce Peninsula region.
Some years back a conservation group cycled 10,000 kilometers of roads in the Bruce region, recording sightings of 2,514 reptiles and amphibians, 1,986 of which were dead. Similar studies in areas such as the Long Point area of southwestern Ontario and the Thousand Islands Parkway to the east have recorded many thousands of amphibian and reptile road kills.
The kills increase as the number of kilometres of roads increase. Ontario had only 7,000 kilometres of road back in 1935 but 60 years later it was estimated to be roughly 36,000 kilometres. And, that number has continued to increase.
Even areas set aside to preserve nature have plenty of roads. Algonquin Park, for instance, is said to have more kilometres of road than the city of Toronto.
Ontario Nature, a conservation organization, has reported that the southern Ontario road network is so extensive that no location now is more than one or two kilometres away from some type of road. Which means that little critters such as frogs, turtles and snakes more often must cross a road during their migrations.
Some municipalities and provinces have become active in providing safer crossings for amphibians and reptiles. In areas of known migration routes, ‘ecopassages’ such as below-road tunnels, above-road wildlife overpasses and special forms of fencing have been constructed. Some areas also have signage such as Brake for Snakes, or turtles.
Driver education also is used to inform drivers about slowing down, being more attentive and learning how to scan the road from side to side for wildlife.
Unfortunately no one has found an effective means of preventing morons from taking the wheel of a vehicle. Ontario Nature estimates that up to four per cent of Ontario motorists intentionally run over snakes and turtles. Many of us have witnessed first hand that kind of idiocy.
The timing of spring migrations usually is subject to weather. If the winter was long and hard and spring late, the migrations will occur later.
If anyone was wondering (I was) about how frogs survive our brutally cold winters, they do so by becoming the living dead.
A high glucose level in a frog’s vital organs keeps it from freezing solid. A frog will partially freeze and it will stop breathing and its heart will stop beating. When surroundings warm the frog’s frozen parts thaw and its heart and lungs begin working again.