Impacts of Roads on Wildlife

By: Brigette Wacker

What Do Roads Really Do to Our Environment?

Effects on wildlife Death by vehicles Enhanced stress (vehicle noise) Reproduction depletion Increased sedimentation in rivers and

streams Increase in Lead, oils, and chemicals Human activities Habitat fragmentation

Vehicle Mortality Estimated 1 million vertebrates

are killed in the U.S. Roads by wetlands have highest

mortality rates A roads width, length, and

speed limit effect road kills. Certain animals are more

susceptible to roads kills on certain roads.

-Amphibians on two lane roads with low to moderate traffic.

- Large and midsize animals are especially susceptible on two lane high speed roads.

- Birds and mammals are susceptible on wide high speed freeways.

Vehicle Mortality Do road kill rates effects

populations? -House sparrow in England

reproduces at higher rates. No effect.

- However other species are including the Florida Panther. Annual depletion of 10% in 1991. Due to mitigation efforts it reduced to 2%.

-Key Deer has an annual depletion of 16% .

-Other species that produce slower than other are also likely to have a decrease.

Vehicle Mortality Often hit vertebrates attracted to

spilled grain, road side plants, insects, basking animals, small mammals, road salt, or dead animals.

May be more frequent where traffic lanes are separated by barriers or between higher roadside banks.

Large natural patches between roads are also likely for road kill as well as wildlife movement areas. These include roads crossing drainage valleys or railway routes.

Landscape and spatial patterns also effects road kill location and rates since animals are linked to certain adjacent or surrounding areas.

Vehicle Noise and Their Effects

Impacts more than road kills. Main cause of avoidance but

also the risk of predators, visual disturbance, and pollution also effects the animals.

In the Netherlands, highways near woodlands and grasslands has showed a 60% decrease in bird density. This was mostly in grassland areas.

Vehicle density also effects the population. Example, with a roads with approximately 5000 vehicles or less, the grassland spices population decreased by road areas.

Vehicle Noise and Their Effects

Impacts include: hearing loss, increase in stress, change in behaviors, interfering with communication during breeding seasons, and decrease in food supply and/or habitat.

Vehicle vibrations for example effect when earth worms come out of the ground and the amount of crows.

The lights alongside roads also changed nocturnal frogs behaviors.

Causes more animals to move farther away and decreases population density.

Road Barriers Affect animal movement. The probability of small

mammals crossing a lightly traveled road is less than 10%.

Road width and traffic also effect the barrier effect.

The barrier effect, creates metapopulations.

Makes crossing more difficult and dangerous.

Increase in Lead, Pollution, and Chemicals

Chemicals Most chemical transport from roads occur

from storm water run-off. Run-off pollutants may be absorbed by

plants and affect stream ecosystems where they are dispersed and diluted.

Salt and heavy metals are most common in road run-off (pollutants.)

A popular deicing agent (NaCl sodium chloride) corrodes vehicles, bridges, contaminates water, and is toxic to many species of aquatic life.

Calcium Magnesium is a more effective deicer. It is less mobile in soil, biodegradable and less toxic to aquatic life.

Increase in Lead, Pollution, and Chemicals

Calcium Chloride, used to decrease dust may inhibit amphibian movement.

Deicing agents increase the mobility of chemical elements in soil, heavy metals. Due to dilution the chemical effects of road run off on surface water may be confined to smaller streams where they run adjacent to roads.

Heavy metals are relatively immobile and distributed on roadsides ( due to drainage flow.)

Surface by roads contain the most. Many other chemicals enter with out

exact cause including pesticides that kill plants.

Increase in Lead, Pollution, and Chemicals

Lead Elevated lead levels were found in the

tissues of small mammals, they lived by roads.

Higher lead levels are on busier roads. In the Netherlands , with a density of

traffic 11,000 – 124,000 veh/day had an increase of heavy metals on the downside

Road run off contributes to more heavy metals in water which helps with fish kills.

Pollution Nitrogen from NOX vehicle emissions

altered vegetation up to 100- 200m from a high way in Brittan.

Hazardous material transported each day in the United States, is often spilled slightly and contributes to server local effects.

Increased Sedimentation Sediment yield depends on sediment

supply and transport. Road surfaces, cutbanks, fill slopes,

bridge/construction sites, and ditches are all sources of sedimentation and increase the problem.

The exposed soil surfaces increase erosion rates and sediment yields.

Land slides caused by roads may increase the amount of sedimentation. Some of the sedimentation collects on a lower slope and accumulates and is subsequent to erosion. The rest goes into the rivers and streams, where it alters ecosystems.

Increased Sedimentation This process is natural but

elevated levels caused by roads help distribute aquatic ecosystems.

Logging roads also increases sedimentation and more erosion by mass wasting.

Increased Sedimentation Buffer strips between roads help

sedimentation problems. Less effective for landslides. Better road placement may help

this issue better than buffers. Road ditches may transport finer

sediments into streams. This disrupts aquatic ecosystems by inhibiting plants, macro-invertebrates, and fish.

Coarse deposits (logs and boulders) create deeper pools and habitat heterogeneity.

During low flow periods finer sediments tend to fill up pools and smooth gravel beds which degrade habitats and spawning sites.

Water Run-Off Altering flows have major consequences

of aquatic live and landscape. The external gravity and resistance

causes streams to create channels to transport chemicals and materials. In which are harmful to aquatic life,

Roads on upper hill slopes concentrate water flows which form higher channels on slopes than on roads.

This process leads to smaller and longer drainage basins and a longer total length of channels.

Increased runoff due to roads may increase the rates and extents of erosion, reduce percolation, aquifer replenishment, alter channel landscape and increase stream discharge.

Roads may also increase peak discharge rates.

Also road cover percentage rates correlate with floods.

Effects on Water Systems Roads may alter surface water flow including on wet land soils. Crossings on wet lands often blocks draining passages and

groundwater flows, which raises the up slope water table and killing vegetation by root inundation while they also raise lowering the down slope, causing more damage.

Human Activities Increase of trash and

pollutants. Humans feed the wildlife

causing them not being able to hunt on their own.

Human noise also effects wildlife.

Habitat Fragmentation The barrier effect. Divides

big populations into smaller more isolated populations.

Can increase with road increase or speed increase.

Genetics of populations

altered due to interbreeding. Cuts off resources and habitat. Increase of habitat

fragmentation means bigger increase in population problems.

Reduces road kills but emphasizes problems with small populations.

Success Story: Coal Cannon A building development tried to take

over Coal Cannon.

Conclusion Roads are altering our wildlife

negatively.