Mitigating reptile road mortality: fence failures compromise ecopassage effectiveness

Area of Science:

• Wildlife Ecology
• Conservation Biology
• Transportation Ecology

Background:

• Roadways significantly impact wildlife populations, particularly reptiles.
• Mitigation measures like exclusion fencing and ecopassages are increasingly implemented to reduce road-related mortality.
• Rigorous evaluations of these conservation tools' effectiveness are scarce.

Purpose of the Study:

• To evaluate the effectiveness of highway exclusion fencing and ecopassages in mitigating reptile road mortality and facilitating movement.
• To assess reptile abundance and road-crossing behavior before and after mitigation implementation.
• To quantify turtle behavioral responses to ecopassages.

Main Methods:

• A Before-After-Control-Impact (BACI) study design was employed.
• Reptile abundance and road mortality were monitored on mitigated and unmitigated highway sections.
• Radio telemetry, wildlife cameras, and automated PIT-tag systems tracked reptile movements and ecopassage use.
• Willingness-to-use experiments quantified turtle behavioral responses to ecopassages.

Main Results:

• No significant difference in turtle abundance on the road was observed between mitigated and unmitigated sections.
• An increase in dead snakes and turtles on the road was detected post-mitigation.
• While reptiles used ecopassages, road-surface crossings were more frequent.
• Turtle willingness to use ecopassages was lower than in previous studies, suggesting compromised effectiveness.

Conclusions:

• Exclusion fencing alone may be ineffective if not properly designed, potentially increasing road mortality.
• Ecopassage effectiveness can be diminished when alternative crossing options, such as gaps in fencing, exist.
• Designing and evaluating mitigation measures based on species-specific biology and behavior is crucial for successful wildlife conservation and adaptive management.