How Can We Lessen the Negative Impacts of Roads on Wildlife?

Human activity (eg, urbanization, population growth) has significantly altered the natural landscape, according to a review recently published in Animal Cognition. Roads have become ubiquitous and, unfortunately, hazardous for wildlife. For example, mortality rates are high for several species because of vehicular collisions; for other species, roads act as physical barriers, subsequently reducing reproductive activity and genetic diversity.

Implementing strategies to mitigate the negative impact of roads on wildlife has become increasingly important. Current strategies, such as constructing physical roadside barriers, are successful but also expensive and time-consuming. Applying learning principles could be an effective strategy, given that cognitive processes largely dictate animal behavior. A key question, the authors wrote, is this: “Can we use learning principles to train wild populations of animals to behave differently?”

Learning Principles

Classical (“Pavlovian”) and operant conditioning use novel cues and signals to change behavior. Classical conditioning pairs two stimuli, and operant conditioning pairs a stimulus with a response. Fear conditioning is a subfield of classical conditioning. Although fear conditioning can help keep animals safe along roadways, it takes time, meaning that an animal may not learn to fear roads before tragedy strikes.

Ensuring that animals can use environmental cues to mediate their fear aids the conditioning process. Several studies have reported how wild animals use auditory and non-auditory cues to recognize and respond to environmental fear.

Fear Conditioning in a Non-Road Context

Fear conditioning has been used to manage wildlife behavior in non-road contexts, both experimentally and in real life. In one experiment, presenting poisonous cane toads to hatchling crocodiles induced a taste aversion in the crocodiles. In another experiment, a captive marsupial species was taught to fear foxes, thus increasing the marsupials’ survivability on release into the wild.

In real life, fear conditioning has been used to prevent bears from seeking human food at national parks. Unfortunately, bears may resume their food-seeking behavior after initial conditioning, highlighting several potential issues: determining when trained behaviors become extinct and when to retrain those behaviors.

Fear Conditioning in a Road Context

To date, application of learning principles in a road context has been lacking. Applying these principles, the authors wrote, “could either enhance or reduce fear associated with roads in a way that benefits both human and animal populations.”

To induce road aversion, the presence of a road could be paired with targeted placement of a fear-inducing stimulus, such as virtual fences. Considerations for this type of fear conditioning include:

• Cost of maintenance
• Extent and timing of retraining animal behavior
• Social transmission of road aversion through an entire population

Not all animals would benefit from road aversion, though. Reptiles and amphibians, for example, often need to cross roads to reach suitable breeding habitats. A solution could be to simultaneously induce fear of the roadside and reduce fear of road-crossing structures.

Road noise can mask acoustic communication, keeping animals away from roads. Conditioning could be used to reduce fear by pairing road noise with a positive stimulus (eg, conspecific song playback for songbirds). Reducing fear of roadside noise could decrease noise-associated stress and encourage habitation near roadways. If animals choose to move closer to roadways, though, the new habitat would need to be examined to ensure it is ecologically suitable for survival and reproduction.

Taken together, learning principles could be used to mitigate negative road impacts on wildlife. Such mitigation, the authors stated, could “save animal lives, drastically reduce the human tragedy associated with vehicular collisions, and reopen vast tracts of habitable land.”

Dr. JoAnna Pendergrass received her doctorate in veterinary medicine from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, LLC.