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Mitigation Measures for Mitigation Measures for Highway Impacts to WildlifeHighway Impacts to Wildlife

Amanda Hardy Amanda Hardy ahardy@coe.montana.eduahardy@coe.montana.edu

**modified by Sandra Jacobson for Innovative modified by Sandra Jacobson for Innovative Approaches to Wildlife and Highway Interactions Approaches to Wildlife and Highway Interactions

ShortcourseShortcourseNCTC 2008NCTC 2008

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Identify the ProblemIdentify the Problem

• MortalityMortality• Loss of habitat connectivityLoss of habitat connectivity

– Daily or seasonal habitat needs– Genetic diversity– Loss of habitat

• Pollution impactsPollution impacts• Disturbance Disturbance • Associated Linear InfrastructureAssociated Linear Infrastructure

– Invasive species

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• Low population Low population survival survival probabilityprobability

• Mass mortalityMass mortality• Public interestPublic interest

Mitigation Mitigation TriggersTriggers

• Safety concernsSafety concerns• Sensitive or Sensitive or

endangered endangered speciesspecies

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Ways to define what “works”Ways to define what “works”• ““Effectiveness” may be defined as:Effectiveness” may be defined as:

– Reduced animal-vehicle collisions (AVCs)– Number of crossings by target species– Adequate number of crossings (how many?)– Connectivity maintained to sustain

populations, communities, ecosystem functions

• Measures of effectiveness may be:Measures of effectiveness may be:– Specific goals (e.g. 50% reduction in AVCs,

cost-benefit ratio threshold >1)

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Effective Mitigation MeasuresEffective Mitigation Measures• Most effective for reducing mortality and Most effective for reducing mortality and

maintaining habitat permeability is a maintaining habitat permeability is a combination of fencing, crossing structure combination of fencing, crossing structure and escape structureand escape structure– Banff:

• Ungulate-vehicle collisions reduced by 96%• All animal-vehicle collisions by 80%

– Wildlife use of crossings increases over time

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More Information Needed to More Information Needed to Determine EffectivenessDetermine Effectiveness

• Herd reductionsHerd reductions• Roadside clearingRoadside clearing• SignsSigns• EducationEducation• At-grade crossingsAt-grade crossings• In-vehicle warning systemsIn-vehicle warning systems• Crossing structures for some Crossing structures for some

objectives such as genetic objectives such as genetic diversity or for low mobility diversity or for low mobility speciesspecies

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Methods with Limited Methods with Limited Demonstrated ‘Effectiveness’Demonstrated ‘Effectiveness’

• LightingLighting• Intercept feedingIntercept feeding• RepellentsRepellents

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Ineffective MethodsIneffective Methods

• ReflectorsReflectors• Deer whistlesDeer whistles• Flagging signs Flagging signs

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How mitigation performs over the long-term depends on accommodating changes in:

Wildlife distributions, abundance and behaviors;

Global warming effects;

Climate change

Ecosystems are dynamic and Ecosystems are dynamic and constantly changingconstantly changing

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General General Mitigation Mitigation

ApproachesApproaches

• Avoid roading good Avoid roading good habitathabitat– “Ausbau über

Neubau!”• Reduce (over-) Reduce (over-)

populationspopulations• Modify Modify

– Driver behavior – Animal behavior

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Modifying Driver BehaviorModifying Driver Behavior

• Reduced Reduced speed limitsspeed limits

• In-vehicle In-vehicle warnings warnings

• Increased Increased visibilityvisibility

• EducationEducation

• Signs: standard, enhanced, limited use (seasonal), real-time Signs: standard, enhanced, limited use (seasonal), real-time detection/warning activationdetection/warning activation

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Modifying Animal BehaviorModifying Animal Behavior

Two approaches:Two approaches:

• Sensory & Sensory & physical controlphysical control

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Modifying Animal BehaviorModifying Animal BehaviorSensory controlSensory control

• ReflectorsReflectors

• FlaggingFlagging

• WhistlesWhistles

• RepellentsRepellents

• Intercept feedingIntercept feeding

• Road salt Road salt alternativesalternatives

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Modifying Modifying Animal Animal

BehaviorBehavior

• Fencing with:Fencing with:

•Under- & Under- & overpassesoverpasses

•At-grade crossingsAt-grade crossingsPhotos: Anthony Clevenger

Physical controlPhysical control

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Steeper than necessarycut slopes

“Elk rock” @ $45 per linear foot

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FloridaFlorida

Tonto NF, AZTonto NF, AZ

Banff NP, CanadaBanff NP, Canada

BanffBanff

Photos: Anthony Clevenger

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