When I think of climate change impacting wildlife, the first image that pops to my mind is the polar bear. Many of us have seen heart-wrenching photographs depicting hungry polar bears trekking across melting ice, in search of their next meal. In this way, polar bears have become a symbolic mascot for climate change. It's easy to visualize how their habitat is directly affected by warming temperatures. Climate change leads to the melting of arctic ice the bears desperately need for hunting. This melting ice drastically influences arctic ecosystems and their species; however, many of the ways climate change influences wildlife are not so cut and dry or easily captured in a photograph.
For many species, climate change does not mean direct destruction; instead, the interconnected nature of ecosystems ensures that small changes will have gradual implications over time. Once one organism exhibits a reaction to a temperature shift, this reaction can lead to changes down the food chain. Eventually, a slight temperature increase can alter the make-up of an ecosystem. Here’s a great example of how climate change is shifting Alaska’s ecosystem composition described in a National Geographic Article:
As depicted above, increasing temperature incites a series of effects on the ecosystem, resulting in new species expanding their habitat into spaces they previously could not occupy. The moose and hare in Alaska are not anomalies in their habitat range shifting North to previously inhospitable territory. Research indicates thousands of species are headed north in search of cooler habitats that will fit their needs more favorably than where they used to call home. This mass wildlife movement is occurring at rates faster than ever recorded. As displayed by this map created by, animal movement is happening all across North America and the rest of the globe.
This is where roads come into the picture.
Currently we are in an era of increasing animal movement toward the poles. At the same time, more people are traveling in vehicles than ever before.
United States Annual Vehicle Miles of Travel
As seen in this figure displaying the trillions of miles driven on US highways, vehicle travel is increasing each year. This lethal combination of climate change driven animal movement and infrastructure development results in more vehicle wildlife collisions occurring than ever before.
It is estimated that between 4 and 8 collisions with large animals take place every hour in Canada alone; however, because of significant underreporting of these incidents, the numbers are likely higher. Since the movement of animals across roads and the number of cars on roads are increasing, both the safety of wildlife populations and drivers are at risk. Wildlife populations on the move are vulnerable to becoming endangered or extinct if they are unable to shift safely into new habitats where the climate could better suit their needs.
Increased snowfall
Another connection between climate change and animal vehicle collisions occurs in northern regions due to increased amounts of snowfall. Because warmer air allows for more water to be held in the atmosphere, a warming climate often results in increased precipitation. In northern regions, this causes more extreme winters and deepening snow.
For foraging animals, deeper snow poses a challenge when looking for food, so animals such as deer and elk are driven into valleys and roadways where they are more likely to encounter road collisions.
A group of white tailed deer cross a rural road. Photo by Rod Laybolt.
Due to this response, researchers have recorded a positive correlation between the severity of winter and the number of vehicle wildlife collisions in local areas. Although foraging animals move to these regions with lower levels of snow for a better chance at finding food, their overall chances of surviving the winter may decrease due to the potential of being hit by a vehicle.
Looking Forward
To protect both drivers and wildlife, it is essential to put mitigation measures in place to reduce the increasing number of wildlife vehicle collisions. Road fencing is often used as a successful means of preventing wildlife from interacting with roads; unfortunately, without pairing these fences with wildlife crossing infrastructure, wildlife may find itself trapped behind a barrier, preventing it from accessing a more suitable habitat on the other side. This issue will only be amplified as climate change continues to alter ecosystems. It is essential to establish corridors for wildlife where populations can travel safely to new habitats if we want to ensure a future of biodiversity.
In order to achieve wildlife connectivity in a time with more road usage than ever before, we are going to need to work together. It will take citizens, private landowners, conservationists, and governmental bodies working together to ensure that wildlife and roads can coexist through climate change.
Allison Dean is the Coordinator of the Watch for Wildlife program and has a B.S. in environmental science and policy from St. Edward’s University.
Resources:
Half of All Species Are on the Move—And We're Feeling It, National Geographic.
https://www.nationalgeographic.com/news/2017/04/climate-change-species-migration-disease/#close
Polar bears across the Arctic face shorter sea ice season, NASA.
https://climate.nasa.gov/news/2499/polar-bears-across-the-arctic-face-shorter-sea-ice-season/
Migrations in Motion, The Nature Conservancy.
Final Report: Collisions Involving Motor Vehicles and Large Animals in Canada, Transport Canada.
How will climate change impact Canada? Canadian Wildlife Federation.
https://cwf-fcf.org/en/about-cwf/faq/faqs/how-will-climate-change.html
How does variation in winter weather affect deer—vehicle collision rates? Daniel D. Olson, John A. Bissonette, Patricia C. Cramer, Kevin D. Bunnell, Daniel C. Coster, Patrick J. Jackson.
Title Photo: Deer crossing the road, by Lisa Davidson
