impacts from roads

How Roads Impact Wildlife – The Environmental Impact

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How Roads Impact Wildlife – The Environmental Impact

Roads have become increasingly common across our globe as people utilize them to travel to places they want to go, increasing the reliability on cars for transportation needs. These large and wide networks of roads we know today severely alter a landscape and can impact wildlife in numerous ways. As seen in my previous blog posts, roads can cause impacts to wildlife such as mortality, wildlife-vehicle collisions, and limit their movement from place to place; however, roads can also shift the population demographic of a wildlife species and become a source of pollution into the environment. Roads impacts extend well beyond the surface of the road itself, causing many ecological impacts to the environment and the wildlife within it.

Habitat Fragmentation & Alteration

Roads can cause direct mortality to wildlife, causing other factors to occur such as wildlife shifting their population demographic farther away from the road, losing vital habitat space. Roads also pose a number of indirect effects onto wildlife, such as habitat fragmentation and alteration. This is due to either wildlife not being able to cross a road due to the risks of mortality or through avoiding the road altogether, shifting their habitat farther away.

Roads also create barriers that limit the movement of wildlife, one of the main issues being barriers prohibit gene flow. An example of this was seen when a group of researchers studied the genetics in timber snakes; snakes that were blocked in their movement from roads had a much lower genetic diversity than other snakes across continuous habitat types. Along with this, the male timber snakes are known to follow pheromone trails to find mates; roads disturb this trail and make it difficult for the males to be able to find mates, affecting reproduction and survival of the species.

Wildlife being affected from habitat fragmentation and alteration are also susceptible to not being able to access specific habitats. An example of this is during dry seasons; when there is a drought occurring, road prohibit wildlife from reaching vital water sources. Roads can also prevent some wildlife from reaching nesting sites, such as turtles; these species end up laying their eggs in habitats where there is more predation, meaning their is a decreased chance of reproductive success and survival of the species.

Constructing a road also alters the habitat altogether. If a road is running through a forest, the road creates an edge habitat along the parts of the road that fringe the forest itself. This can have severe consequences for wildlife, especially birds; when an edge habitat is created, birds become more susceptible to predation. This is due to predators being able to prey on birds much easier in the edge habitat, as the forest canopy at the edge offers less protection to the birds and their nests. Other wildlife susceptible to edge habitats are turtles; some species of turtle prefer to nest along edge habitats because it is an ideal habitat for their nest. However, turtles utilizing the edge habitat are now posed to a greater risk of mortality when crossing roads, and their hatchlings could also be susceptible to this when they disperse after hatching from the nest.

Pollution

While roads can alter habitats and cause fragmentation to occur, they can also channel pollutants onto the environment. Debris from tires on the road can cause things such as a decreased amount of time to metamorphosis for the wood frog species. Salt that is used to deice roads runs off the road and into adjacent ponds that can decrease the survivorship of species such as spotted salamanders and wood frogs. Deicing salts can also change frogs behavior and decrease their performance in locomotion. Frogs are one the species that have been shown to have greater skeletal abnormalities when they are closer to roads; researchers suggest this is a result from the road contamination. This is turn affects the frogs fitness, making them potentially less adept to catch prey or elude themselves away from predators.

Roads polluting the environment extend far beyond introducing chemicals into the environment; they also introduce noise and light, which can be detrimental to wildlife as well. The noise from traffic on a road can effect species of bird, causing declines in bird populations living in proximity habitats close to the road. However, not all species of bird are equally affected, such as how birds having song frequencies similar to that of a car frequency being found as absent from habitats near roadsides. Noise from a road can also change bird species’ community composition, meaning that some species of birds are differentially excluded from a particular habitat near a road.

Along with noise polluting the environment, light can as well. Some species of wildlife rely on light to control biological activities, and this can be impacted by lights along a road. For example, robins use sunlight as a cue to begin their morning songs and can mistake lights on a road for the sun and begin their song in the middle of the night. Lights from roads can also alter flying routes for bats, as well as expose some frog species to artificial light during the night that could delay their metamorphosis time. Along with this, sea turtle hatchlings use light in order to navigate themselves to the sea and can become confused by lights on a road and go toward a road instead of the ocean; this can cause the hatchlings to die from dehydration, predators, and /or wildlife-vehicle collisions, and they will never reach the ocean. This goes for the females that nest their hatchlings as well, sometimes becoming disoriented from road lights and have a difficult time getting back to the ocean.

A final note on pollution from roads is that is can facilitate the spread of invasive species when land is cleared for a road. An example of this was seen in Australia with cane toads; these species of toad are very invasive in the continent and use roadside areas to move, causing an increase in their range as a population. Along with this, species such as fire ants may also build their mounding nests by areas cleared for roads because this is an ideal habitat for them. Roads can facilitate the invasion of invasive species, and alter or fragment a habitat; all of this impacts are detrimental to both wildlife and the land they live in.

Mitigation Strategies

There are numerous solutions and mitigation strategies being developed to help decrease the amount of harmful impacts our roads cause to wildlife. In instances where the pattern of mortality can be predicted for a specific are during a specific time of year, roads are either closed or reduced in their speed limits to decrease the rates of wildlife mortality. Another solution is creating artificial nesting sites for gravid species that need them; this can reduce species from needing to potentially cross a road, the distance they need to travel, and/or their chances of mortality.

A main issue with roads is the traffic volume on them. Though decreasing traffic volume is not very likely to be effective for a mitigation strategy, constructing alternative methods to cross a road could become more successful. For example, culverts can be used for smaller animals to allow for a safe passage under a roadway; this has been shown to be highly effective in decreasing mortality rates of wildlife. For bigger animals, overpasses can be used to cross a road; this overpass would need to have specific features of the wildlife’s environment, such as vegetation planted over it to mimic the habitat type.

There are many factors that need to be taken into consideration when ensuring wildlife can effectively and efficiently cross our road structures. We need to implement and create new ways to protect and preserve our wildlife, as well as the environment they live in. From this post, we have learned that roads not only impact wildlife through things such as mortality or vehicle collisions, but roads also create very real and severe threats to the environment that in turn affect wildlife. We as humans have a job of conserving our planet, and that includes the wildlife within it. Without the wildlife, there would not be an environment for us to destruct upon, as wildlife naturally disperse seeds, nutrients, and vital resources the environment needs to keep going.

“We are part of the environment, just as much as wild animals are. They do not seek to kill us, we seek to kill them. It’s surely our responsibility to do everything within our power to create a planet that provides a home not just for us, but for all life on Earth.” – David Attenborough.

How Roads Impact Wildlife – Anthropogenic Noise

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How Roads Impact Wildlife – Anthropogenic Noise

From the major transportation infrastructures we use everyday of our lives, from highways to simple roads through the suburbs, we as humans may not notice the effects of a vehicle driving on a road. What is not noticed enough is the amount of anthropogenic noise produced from roads and traffic, and how this in turn effects the wildlife around us. How does anthropogenic noise effect our wildlife species, and how can we resolve this issue?

Roads & Traffic – Too Noisy?

Through human development, anthropogenic noise is introduced into the environment across multiple aspects of terrestrial landscapes; this includes, but is not limited to, airports, roads, and highways. Anthropogenic noise is known as a global phenomenon in today’s world, having the potential to impact wildlife species across every continent and habitat type.

Transportation systems are one of the most pervasive sources of anthropogenic noise across every landscape, including from sources such as roads and the traffic volume associated with it. Roads are very widespread and produce an increased amount of noise; though they may seem to cover a small surface area, the ecological impacts of roads and the noise associated with them extend well beyond a road itself. Anthropogenic noise from roads affects about one fifth of landscapes in the U.S., becoming problematic for wildlife due to the noise volume produced being very loud.

Anthropogenic noise also has varying characteristics that differentiate from the sources it comes from, such as the amplitude (or loudness), frequency (or pitch), and spatial and temporal patterns of the noise; this in turn determines the impact noise has on wildlife. This noise can affect wildlife both at an individual level and at a population level.

How Anthropogenic Noise Impacts Wildlife

On an individual level, wildlife are impacted by anthropogenic noise through the acute impacts noise can cause; these effects include physiological damage, masking of communication, disruption of behavior, and startling to an individual animal. Physiological damage to an individual animal can cause the animal’s inability to hear, either by permanently damaging the auditory system causing a permanent threshold shift (PTS) in the individual’s hearing, or by temporary reductions in the animal’s hearing sensitivity, known as temporary threshold shifts (TTS).

In terms of masking an animal’s communication, this happens when an animal perceiving a sound is impacted by the background noise (i.e., anthropogenic noise) and cannot make out the acoustic communication being relayed because it is masked. If this occurs, this will ultimately cause a decrease in acoustic communication between individuals or species. Acoustic communication is used by animals to attract and have mates, distinguish territory, promote social bonding, and alert others if a predator is nearby. If anthropogenic noise masks the acoustic communication, this can have dramatic effects on reproduction and survival of a species.

Anthropogenic noise can also cause an individual animal to suffer from chronic effects, such as elevated stress levels and associated physiological responses with it; this in turn can cause long-term welfare and survival consequences from anthropogenic noise effecting an animal.

Anthropogenic noise effects wildlife at a population level through how it can range from causing things such as population decline up to a regional extinction of a species. This is especially critical for species that are threatened or endangered due to habitat loss; if a species begins to avoid even more habitats due to anthropogenic noise, their status becomes more critical and could result in possible extinction.

Wildlife species have varied responses in their tolerability to anthropogenic noise due to their altered acoustic environments. For example, when a major transportation infrastructure is placed into an environment, studies have shown that the amount of species present near the road are greatly reduced from what they were before the road was placed; this majorly due to the road itself and the associated anthropogenic noise coming from it.

Anthropogenic noise coming from roads can also mask the communication of species, as stated above, and cause a decrease in their acoustic communication and in turn effect their reproduction and survival as a whole. However, how can we as humans reduce the amount of anthropogenic noise produced from our major transportation infrastructures to reduce the impacts it has on our wildlife?

Animals to humans: Be quiet!

Future Directions for Anthropogenic Noise

Though human development and the associated anthropogenic noise are rapidly spreading in our advanced world, there may not always be a logistically, politically, or economically feasible way to eliminate or even minimize anthropogenic noise altogether. However, there is a common approach that can be used, being to set noise standards for when major transportation infrastructures are implemented in hopes to limit the level of noise being produced into the environment. This would mean that when a road or highway is implemented, the noise production can be reduced either operationally or structurally to meet the noise standards.

An example of this can be shown through how road noise can be decreased by using specific types of asphalt, though this could also cause the road’s surface to have lower durability and traction. Another solution to reduce road noise could be to implement noise barriers along a road, however, these may also cut off migration routes and enhance rather than decrease the road impacts overall. So, how do we go about decreasing the anthropogenic noise imposed onto the wildlife around us?

Most of environmentalists researching this have discussed using a single noise standard that covers all anthropogenic noise situations; however, this does not account for all species and how the anthropogenic noise impacts each individual species. Rather than using a single noise standard, there should be a set of standards established that would be based off the measurement of sensitivities for species in specific concern or in a specific habitat location or type. If this set of standards were developed, this would be that wildlife would not suffer as much from the anthropogenic noise produced from human structures, while addressing how sensitive each species is to anthropogenic noise. We as humans don’t like hearing too much background noise and having it affect us daily, causing us things such as stress or not being able to effectively communicate with others. Why should let our wildlife be susceptible to this?

How Roads Impact Wildlife – Increased Human Exploitation & Recreation

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How Roads Impact Wildlife – Increased Human Exploitation & Recreation

The human footprint on the world is expanding more and more everyday, and people and wildlife are coming in greater contact with one another; this means that the areas humans use for activity or recreation could be simultaneously associated with the risks towards animals. Human recreation is one of the biggest exploitations to wildlife, including facets concerning public access on roads, motorized summer trails and winter trials, cross country ATV and snowmobile use trails, and/or water access trails.

Human Exploitation & Recreation on Wildlife

Wildlife experience many impacts from humans and roads in general, however, the impacts wildlife endure from human activities and disturbances can include the following: physically altering a habitat, removing vegetation or replacing native species with disturbance-tolerant non-native species, and increased noise, sight, or sound from people. Human recreation impacts wildlife through the exploitation, modification, disturbance, and pollution it imposes on the environment.

Any disturbances caused by human recreation or other activities by humans could cause wildlife species to elicit behavioral and physiological responses. These responses are usually influenced by the disturbance itself (i.e., activity type, distance away from the species, direction or movement , speed, frequency, predictability, and magnitude) and/or the location in relation to the animal itself. The type of behavioral response wildlife elicit is in the form of avoidance, habituation, or attraction; more times than not, wildlife will avoid areas where humans recreate or exploit. Examples of specific recreational activities that impact wildlife include:

  • Hunting – can alter the sex and age composition, distribution, reproduction, and behavior of wildlife
  • Viewing – can disturb wildlife through things such as close encounters, and cause changes in the animal’s energy expenditure, alter their nest or burrow site, and decrease the ability of their young to survive (i.e., animal’s will sometimes abandon their young when human’s are near because they are deemed as predators)
  • Backpacking/Hiking, etc. – can cause increased flight risk, stress, and/or displacement of wildlife
  • Boating – can alter the habitat quality or foraging quality for waterfowl species, and can also impact the quality of the water wildlife are exposed to
  • RMV’s – can cause wildlife to redistribute from disturbances such as flight or stress

How Human Recreation & Exploitation Stems from Roads

The impacts described above on how wildlife endure effects from human recreation and exploitation are accessible from one of two places: roads or trails. Public access roads disrupt the wildlife’s habitat continuity to one extent or another, usually dividing a big area of habitat into smaller patches. These types of roads can also inhibit movement for animals migrating, enhance linear openings of roads that are detrimental to wildlife, and cause habitat or forest fragmentation.

Motorized summer or winter trails for ATV’s, snowmobiles, RMV’s, or even water access trails, have negative effects to wildlife, including the following: physically altering the habitat area, removing vegetation, replacing native vegetation with non-native vegetation, increased noise disturbances, reduced habitat security, and sometimes resulting in direct injury and/or mortality to the wildlife. All of these impacts to wildlife species result from any form of human recreation and/or exploitation; yet, how can we as humans make the environment a better place for wildlife to live and thrive in?

Solutions to Human Recreation & Exploitation

A current solution being used to stop the human recreation and exploitation along motorized recreational trails is to identify the standard of the forest (i.e., low standard meaning there is little to no quality left; high standard meaning there is much quality) and deciding if the trail should remain opened or closed. This is dependent on local and national level ownerships of land, and whether or not the wildlife in the area being considered will benefit from the trail closing or not be affected whether it’s open or not.

Other solutions to the issue of human recreation and exploitation from roads and trails would be to have maintenance and public information available to people who utilize human recreation areas, roads, and trails; this would help improve the public’s knowledge of where it is okay and not okay to recreate. From these solutions, road related impacts to wildlife could considerably decrease due to more people taking the necessary precautions to protect an area of land and the wildlife within it.

An example of how to humanly recreate within an environmental area that wildlife are home to could be to follow the indicated trails when going on a hike instead of detouring away from the trail. Another example could be to take the time to research the area you’re going to be recreating in and understanding the precautions needed to ensure wildlife are not harmed and/or disturbed. Recreation should be utilized, to hike, explore, and be apart of different areas of nature, but should be done so in a safe and cautionary way to protect and not exploit upon the wildlife within our environment.

How Roads Impact Wildlife – Indirect Effects to Our Wildlife Species

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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.

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