road avoidance – Ryann O'Carroll

How Roads Impact Wildlife – Road Avoidance

rocarroll Wildlife June 9, 2020June 17, 2020barrier effect, impacts to wildlife, road avoidance, road ecology, roads, solutions for wildlife 0 Comment

Roads have become integrated into our world and are a central function to human society. When barriers are placed around roads, this in turn affect wildlife’s ability to move as well as the trajectory and evolution of wildlife populations; this is known as the barrier effect as wildlife learn to avoid roads with barriers around them. However, how exactly do barriers impact our wildlife and cause them to avoid roads?

The Barrier Effect

Roads can impose a barrier effect to occur in wildlife populations, causing wildlife to decrease their dispersal rates and limit the amount of demographic rescue and gene flow within a population; this in turn increases the species potential of going extinct. The barrier effect is related to the impacts of roads and affects several wildlife populations; it’s usually caused by behavioral responses to roads (i.e., road avoidance), emissions associated with the road (i.e., traffic-emissions avoidance), and/or the circular activity of vehicles on a road (i.e., vehicle avoidance).

Road avoidance by wildlife is usually dependent on the surface material of the road itself or the clearance of vegetation near the road. Traffic-emission avoidance is dependent upon the long-ranging disturbances coming from roads, such as dust, light, vibrations, and/or noise. Vehicle avoidance is dependent upon the behavioral response of a species of wildlife that has the movement and cognitive capacity to avoid vehicles on a road. All of these types of avoidances are drivers of the barrier effect and cause wildlife to avoid roads.

An example of the barrier effect can be seen with the federal plans to complete a continuous wall along the U.S.-Mexico boundary. Implementing this wall would threaten the existence of multiple plant and animal species, as many species migrate terrestrially between the U.S. and Mexico. Though this example is not of a road itself, it emphasizes why wildlife populations have road avoidance due to barrier effects.

Barriers, whether along a road or between countries, present physical limitations to wildlife, preventing and/or discouraging wildlife from accessing vital resources such as food, water, mates, or disrupt annual or seasonal migration and dispersal routes. These barriers, whether border walls or for transportation infrastructures, not only affect wildlife, but also cause habitat fragmentation, soil erosion, changes in fire regimes, and altering of hydrological processes through causing floods. From this, it seems that each species of wildlife has a how and why to the reasons for road avoidance, however, this is an issue that needs future considerations and research needs.

Future Considerations & Research Needs

Behaviors vary across all species of wildlife, however, with the use of basic ecology, predictions can be made for the primary response wildlife populations will have to roads and therefore provide increased predictive ability about how barrier effects of roads are perceived as a risk to wildlife. This is a solution for researchers concerned about this issue, as they can conduct studies on specific species of wildlife or a specific road to understand why the animals in that area are avoiding it.

Other solutions can include the need to identify species surrounding the road area, the habitats and ecological resources at risk from the barrier being constructed, designing barriers to have maximum wildlife permeability wherever possible, and/or restoring habitats when the harm to the environment is inevitable. Though we may be a long ways away from finding a solution to wildlife displaying barrier effects from road avoidance, researchers can still assess the primary responses of wildlife species to better understand what the causes of road avoidance may truly be, and help to construct better roadway systems for both wildlife and the environment in the future.

The barrier effect is a very real and pervasive threat to wildlife, as it may cause them to avoid certain areas of vital habitat key to their survival all because of our major transportation infrastructures deterring them away. Collaboration from researchers based in wildlife biology, ecology, and even road ecology could all work together to implement the solutions listed above so our roads no longer deter our wildlife from their native land.

How Roads Impact Wildlife – Indirect Effects to Our Wildlife Species

rocarroll Wildlife June 9, 2020June 24, 2020chain reaction, degradation, disturbances, habitat loss, impacts from roads, impacts to wildlife, increased human exploitation, indirect effects, major transportation infrastructures, road avoidance, road ecology, roads, solutions, solutions for wildlife 0 Comment

Roads impact wildlife in a variety of ways, as seen through my many blog posts concerning this topic and issue. However, the one major thing I have not yet discussed about how roads impact wildlife is exactly what happens to our wildlife in terms of their diversity and size. Roads can cause a chain effect of reactions to occur in the environment, including diminishing species one by one, gradually decreasing the size of their population.

Wildlife are Gradually Disappearing

Major transportation infrastructures (i.e., roads, railways, and canals) are impacting our wildlife across an array of linear landscapes, making wildlife become disproportionate to the area of habitat they occupy. As we know, roads impose an array of impacts to wildlife, including wildlife mortality, wildlife-vehicle collisions, and limited movement from habitat to habitat. However, what is of major concern is the indirect effects roads cause to our wildlife populations, such as reduced access to habitat due to road avoidance or human exploitation. The indirect effects are the ones of major concern, especially those occurring from bigger transportation infrastructures such as highways. Highways present more serious and harmful threats to wildlife and impact a much larger range of wildlife species, presenting impassable barriers for species to move around their environment. The major concerns of highways, and transportation infrastructures in general, and their indirect effects include, but are not limited to, direct loss of habitat, degradation of habitat quality, road avoidance, and human exploitation.

The Indirect Effects

Direct loss of habitat is one of the indirect effects wildlife experience from our roads and highways. Construction of major transportation infrastructures changes the value of the habitat within the landscape. Areas that used to flourish in the environment that are now covered by pavement, rails, or travel lanes with dirt and/or gravel are now vastly diminished to be used by wildlife as habitat. Transportation infrastructures also cause the quality of a habitat to degrade, causing things such as storm water discharge, alterations in stream hydrology, air emissions, and invasive plant species to occur; this can degrade a habitat not just where the transportation infrastructure is placed, but several hundred meters or even miles away from the road itself.

Due to roads running through wildlife habitat or landscapes wildlife use, wildlife become accustomed to avoid roads. Some species of wildlife will avoid areas adjacent or close to highways or roads due to the amount of noise and/or human activity associated with roads in general. Avoiding areas near roads can cause wildlife to be restricted in their ability to move around in their environment, limit the resources they can access, and limit the amount of food they are able to forage for. Roads are also associated with human activity to wildlife, which means increased human exploitation in these areas; roads increase the access for humans to hunt or poach in the environment. This effect can potentially cause wildlife populations near roadway areas to be vastly reduced, leading to wildlife becoming more road avoidant in the future. How can these indirect effects to wildlife from roads be resolved, even just a little, to help our species of the earth?

The Solution to the Indirect Effects

Based off an article I found about this issue imposed onto our wildlife, there are already progressions being made with resolutions to the issue of indirect effects from road systems. One solution is to foster a greater appreciation for the issues caused by highways and railways; this is a challenge currently because it emphasizes the understanding people need to have for the scope and complexity transportation infrastructures pose on wildlife. The issue is sometimes too often viewed as incidental to the animal rather than a threat to wildlife populations. Wildlife must be able to move throughout their landscapes as it is one of the most important ecological processes that needs to be maintained for ecosystems to stay intact over time. Being able to foster an appreciation for this issue is important, as it could lead to appropriate planning and mitigation when roads are being constructed to prevent long-term degradation of wildlife populations and their habitats.

Another solution to this issue to be able to analyze the landscape’s connectivity zones; what this means is when a road is being planned for construction, comprehensive efforts must be taken to acknowledge and leave be the areas in the landscape that are deemed important travel corridors or connections for wildlife between significant habitat areas. If these steps are taken, planning for new transportation infrastructures can be more effectively and efficiently focused on how to minimize and mitigate the impacts to critical areas wildlife use. Though these solutions are still in the making, the causes of indirect effects from roads onto wildlife is an important topic that needs to be explored so we still have the wildlife we love and see all over the world.