A Review of Wildlife–Vehicle Collisions: A Multidisciplinary Path to Sustainable Transportation and Wildlife Protection

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. The title is engaging, but it might benefit from clarifying that this is a review article—perhaps by adding "A Global Review" or "A Review on Wildlife–Vehicle Collisions"?
2. Can you elaborate more on how this review differs significantly from previous comprehensive reviews on road ecology, such as those by Coffin or Forman?
3. The paper effectively categorizes impacts and mitigation strategies. However, some subsections (like behavioral adaptations and scavenger effects) are dense—would subheadings or bullet-point summaries help here?
4. The impact of roadkill on endangered species is alarming. Have you considered highlighting this more prominently through a comparative table or an endangered-species-specific section?
5. Your coverage of AI, thermal imaging, and AV technology is excellent. However, could you add more critical analysis about the challenges of implementing such technologies in developing countries or rural areas?
6. You mention autonomous vehicles (AVs) briefly—do you see ethical concerns or potential unintended consequences of their deployment for wildlife that should be further discussed?
7. The section on emotional and psychological impacts is unique and compelling. Could you recommend how these insights might be integrated into driver education or public policy?
8. You mention that few driver training programs include wildlife collision prevention. Would it be useful to suggest a minimum global standard or checklist for such training?
9. The manuscript does an excellent job of demonstrating the complexity of roadkill impacts. Could you end with a more strongly worded call for international collaboration or policy action?
10. Consider developing a graphical abstract or a summary infographic to support knowledge dissemination among policymakers and general readers

Author Response

Reviewer#1 comments and answers

1. The title is engaging, but it might benefit from clarifying that this is a review article—perhaps by adding "A Global Review" or "A Review on Wildlife–Vehicle Collisions"?

Answer: we changed Title as recommended, using the second option.

 

1. Can you elaborate more on how this review differs significantly from previous comprehensive reviews on road ecology, such as those by Coffin or Forman?

Answer: The foundational works by Forman and Alexander (1998) and Coffin (2007) provide critical early insights into the ecological impacts of roads, particularly emphasizing habitat fragmentation, roadkill, and landscape-scale effects. However, these papers lack several elements that have since become essential in the study of wildlife–vehicle collisions (WVCs) and road ecology. They do not include a global perspective, focusing on North America, parts of Europe, and Australia. They do not incorporate recent technological advances such as drones, AI-based analysis, mobile apps, and citizen science tools, which have significantly improved roadkill monitoring and mitigation in recent years. Furthermore, they do not explicitly connect road ecology to broader sustainability goals or transportation policy, missing the opportunity to frame roadkill as both an environmental and socio-economic issue. Neither of these papers use a transparent, reproducible methodology for literature selection or gap identification. They omit newly emerged themes such as the use of roadkill data for disease surveillance, the ecological role of scavengers, and detailed cost-benefit analyses of mitigation strategies. These gaps highlight the need for updated, interdisciplinary reviews that reflect the global, technological, and policy-driven evolution of road ecology.

However, we find this too long to include, therefore present very short text added to Line 47:

The last two papers were foundational in road ecology but lack several key elements now considered essential. They have little global representation, and do not include recent technologies like AI, drones, or citizen science. They also miss connections to sustainability goals, economic impacts, and transportation policy. Unlike modern reviews, they lack systematic methodology and overlook emerging topics such as disease surveillance through roadkill, scavenger ecology, and cost-effectiveness of mitigation. These gaps underscore the need for updated, interdisciplinary approaches in road ecology research.

 

1. The paper effectively categorizes impacts and mitigation strategies. However, some subsections (like behavioral adaptations and scavenger effects) are dense—would subheadings or bullet-point summaries help here?

Answer: Thank you for this suggestion. We agree that the sections on behavioral adaptations and scavenger effects contain dense information. However, the manuscript already includes a substantial number of subheadings, and adding more could fragment the narrative flow. Mentioned issues, section 3.1.7 has only 2 paragraphs, and 3.2. – 3 short paragraphs. There is no point to introduce additional items.

 

1. The impact of roadkill on endangered species is alarming. Have you considered highlighting this more prominently through a comparative table or an endangered-species-specific section?

Answer: we suppose that separate chapter 3.1.4. Endangered Species at Risk is already a highlight. In fact, with nearly 100 threatened mammal species impacted by roadkills, the issue deserves separate analysis and review paper. Within the broad scope of the current review we do not see possible to give more space on the species vulnerability. We would be eager to cooperate with any other author outside Europe on the roadkill - -mammal vulnerability analysis.

 

1. Your coverage of AI, thermal imaging, and AV technology is excellent. However, could you add more critical analysis about the challenges of implementing such technologies in developing countries or rural areas?

Answer: Thank you for highlighting this important point. We have expanded our discussion to include a more critical analysis of the challenges associated with implementing advanced technologies such as AI, thermal imaging, and autonomous vehicle (AV) systems in developing countries and rural areas. Specifically, we now address barriers such as high initial costs, limited infrastructure, possibly the lack of reliable electricity and internet connectivity, and the need for technical expertise and maintenance capacity. While these innovations hold great promise, their deployment outside high-income settings often requires adaptation to local conditions and cost-effective alternatives. The revised text added as the final sentence of Discussion.

 

1. You mention autonomous vehicles (AVs) briefly—do you see ethical concerns or potential unintended consequences of their deployment for wildlife that should be further discussed?

Answer: We do not see potential negative consequences of AVs already analyzed, but there are theoretical thoughts outside the scope of our review. To address these, and answer your comment, we included text and two additional references, “Autonomous vehicles have the potential to reduce WVCs, but this benefit depends on the ethical and technical priorities of their design. Current frameworks call for integrating animal detection into AV decision-making systems, yet challenges remain in ensuring protection for a broad range of species, especially smaller or less conspicuous ones, which may be excluded due to algorithmic bias or cost constraints [289,290]. Without proactive consideration of wildlife in AV development, there is a risk that these vehicles will replicate or even reinforce harmful human driving behaviors toward animals.”

 

1. The section on emotional and psychological impacts is unique and compelling. Could you recommend how these insights might be integrated into driver education or public policy?

Answer: Driver education programs should incorporate emotional and ethical aspects of wildlife–vehicle collisions, highlighting the psychological impacts and ethical responsibility toward animals. Public policy should support targeted awareness campaigns and require wildlife hazard modules in licensing, especially in high-risk regions. Additionally, integrating mental health resources for drivers affected by severe WVCs can help address the often-overlooked psychological consequences.

We added a paragraph of text in the end of Section 4.3.

 

1. You mention that few driver training programs include wildlife collision prevention. Would it be useful to suggest a minimum global standard or checklist for such training?

Answer: such suggestion is out of scope of our review, and in the cited references there are no proposals as for the standard. Minimum global standard (checklist) for wildlife‐collision prevention in driver training programs is intended to address legal liability and regulatory compliance issues, not to manage or discuss wildlife roadkill.

 

1. The manuscript does an excellent job of demonstrating the complexity of roadkill impacts. Could you end with a more strongly worded call for international collaboration or policy action?

Answer: acknowledging your comment we add final sentence “Therefore, governments, scientists, and conservationists must collaborate on a global scale, sharing policies, resources, and binding agreements, to develop adaptive, local solutions that reduce extent of the wildlife–vehicle collisions.”

 

1. Consider developing a graphical abstract or a summary infographic to support knowledge dissemination among policymakers and general readers

Answer: we made timeline as GA

 

Reviewer 2 Report

Comments and Suggestions for Authors

The paper provides a comprehensive overview of the history and current state of research on wildlife-vehicle collisions (WVCs) and roadkill. However, it would be beneficial to include more specific examples of successful mitigation strategies and their impact on both wildlife populations and human safety. Can you provide some case studies or real-world examples of effective WVC mitigation measures?

1. The paper mentions the importance of interdisciplinary collaboration in addressing road ecology challenges. How can researchers and practitioners better facilitate communication and cooperation among different fields, such as transportation engineering, wildlife biology, and social sciences, to develop more holistic solutions?
2. The paper highlights the negative psychological effects of roadkill events on humans. Are there any ongoing initiatives or research projects focused on developing interventions or support systems to help people cope with these emotional impacts?
3. The paper discusses wildlife protection in transportation systems. Traffic flow modeling is one important technique in Intelligent Transportation Systems. There are a series of traffic flow forecasting models to improve traffic flow, such as GSA-KAN. Is accurate traffic flow forecasting may improve wildlife protection?
4. The paper suggests that data integration and dynamic modeling can improve our understanding of road ecology challenges. What specific types of data should be collected and analyzed, and what tools or techniques are currently available for integrating and analyzing this information effectively?
5. The paper emphasizes the need to balance infrastructure development and environmental conservation. How can policymakers and stakeholders make informed decisions regarding transportation infrastructure expansion while minimizing the adverse effects on wildlife populations and ecosystems?

Author Response

Reviewer#2 comments and answers

Comment: The paper provides a comprehensive overview of the history and current state of research on wildlife-vehicle collisions (WVCs) and roadkill. However, it would be beneficial to include more specific examples of successful mitigation strategies and their impact on both wildlife populations and human safety. Can you provide some case studies or real-world examples of effective WVC mitigation measures?

Answer: Number of case studies and examples are provided in the chapter 3.5.1. Measures Focused on Wildlife Protection, along with references to these studies. In most cases, effectivity is also shown, mostly as percent of WVCs reduction.

 

1. The paper mentions the importance of interdisciplinary collaboration in addressing road ecology challenges. How can researchers and practitioners better facilitate communication and cooperation among different fields, such as transportation engineering, wildlife biology, and social sciences, to develop more holistic solutions?

Answer: We add final sentence “Therefore, governments, scientists, and conservationists must collaborate on a global scale, sharing policies, resources, and binding agreements, to develop adaptive, local solutions that reduce extent of the wildlife–vehicle collisions.”

However, we are doubtful as for the practical implementation of such projects, as they face different legislation in cooperating countries, not speaking of financial problems and logistic. Currently there is an initiative titled Proposal for Establishing the IENE Working Group: Monitoring European Fauna Passages. This might become good example of very wide international cooperation (if succeeded).

 

1. The paper highlights the negative psychological effects of roadkill events on humans. Are there any ongoing initiatives or research projects focused on developing interventions or support systems to help people cope with these emotional impacts?

Answer: a number of both grassroots and formal research efforts to develop targeted interventions and support networks for eco-grief, eco-anxiety and related distress were developed, including

Climate Psychology Alliance (https://www.climatepsychologyalliance.org/)

Good Grief Network & Youth Programmes in partnership with Climate Cafés

Global Mental-Health Alliances (https://www.climatepsychology.us/),

There is a review on the Eco-anxiety, DOI:10.3390/ijerph18189636, and also Eco-Coping Qualitative Study, DOI:10.3390/ijerph19042461.

However, there aren’t any large-scale intervention or support programs that focus on roadkill-related distress. Wildlife-rescue volunteer organizations often offer informal peer support and training, but dedicated research-backed interventions for roadkill trauma have yet to be developed.

 

1. The paper discusses wildlife protection in transportation systems. Traffic flow modeling is one important technique in Intelligent Transportation Systems. There are a series of traffic flow forecasting models to improve traffic flow, such as GSA-KAN. Is accurate traffic flow forecasting may improve wildlife protection?

Answer: On an example of GSA-KAN (Lin, Z.; Wang, D.; Cao, C.; Xie, H.; Zhou, T.; Cao, C. GSA-KAN: A Hybrid Model for Short-Term Traffic Forecasting. Mathematics 2025, 13, 1158. https://doi.org/10.3390/math13071158), traffic flow forecasting models so far are not used in roadkill mitigation. We agree, that in the future there can be changes, and we would like to cooperate with scientists working in traffic planning, to get more use of our roadkill data. However, to include these models in the review is premature. To our best knowledge, Intelligent Transportation Systems so far omit roadkill issues.

 

1. The paper suggests that data integration and dynamic modeling can improve our understanding of road ecology challenges. What specific types of data should be collected and analyzed, and what tools or techniques are currently available for integrating and analyzing this information effectively?

Answer: We already answered this question. In short, our review highlights essential data types for road ecology studies, including: 1. wildlife mortality details (species, demographics, timing of collisions), 2. spatial and environmental data (GIS mapping, habitat connectivity, traffic, weather), 3. animal behavioral and ecological traits (movement patterns, responses to roads, species characteristics), and 4. human-related factors (collision reports, economic costs, psychological impacts). All these data will add also to mitigation success.

 

1. The paper emphasizes the need to balance infrastructure development and environmental conservation. How can policymakers and stakeholders make informed decisions regarding transportation infrastructure expansion while minimizing the adverse effects on wildlife populations and ecosystems?

Answer: we added near-final sentence, which partially answers your question. In addition, policymakers can balance infrastructure and wildlife conservation by using integrated ecological planning, adaptive management, and collaborative mitigation approaches like wildlife crossings. However, cross-sector cooperation remains difficult due to differing priorities, communication barriers, institutional differences, funding constraints, conflicting short- and long-term goals, and complex regulations.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors present a comprehensive review of roadkill research from published analyses in the 1930s from North America to a contemporary view of the last few decades. The review is based on a literature search which is well-illustrated in Figure 1 but a bit muddled in the text. The sample is biassed to Europe and USA and somewhat thin from other regions (e.g. few references to Oceania relative to effort). The tendency is to use a few exemplars from other regions (e.g. Brazil, East Asia) as case-studies to support or round-out the generalizations presented. The literature is summarised under several headings (some with sub-headings) that include impact on wildlife, wildlife behaviour, patterns and determinants, human dimensions, and mitigation. These provide an excellent overview not withstanding the bias in the fauna. In some instances, the examples tend to stray off topic. The discussion likewise is under several headings with an appropriate focus on gaps and future directions to arrive at interesting and pertinent conclusions.

The writing is a bit erratic with some sections peppered with grammatical errors, especially missing articles. One omission is to present common names only for all fauna species. The species binomial in italics should be included either with the first mention in the text or alternatively the authors could provide an appendix of all common and species names.

In the following, I suggest some revisions for minor errors.

L37: in the 1990s

L61: using a systematic

L63: defined the scope…to include

L66-7: a discussion of research gaps…ecology.

L67-8: The timeframe for the analyzed sources is the last…with a limited

L68-9: The taxonomic…and the geographical

L70: Papers were

L71: including a limited

L72: mainly “roadkill”

L75: Explain other?

L76: In looking

L78: hundreds of records…Scholar alone

L81: Therefore, most

L85: an AI-based

L86: check if

L88: After a draft

L89: the number of

L90: of the grey

L91: and finally papers

L104: roads expands

L107: the last two

L112: A multi-country

L144: in the Czech

L148: results contrast

L161: the largest

L165: a negligible

L168: increasing the

L182: and reduction

L185: as the population

L191: Inconsistent attribution of state to country which is USA, check other state references

L227: Seems off-topic why is it similar?

L226: intensity is exceeded…became impermeable

L287: Off-topic?

L317, 321: species names in italics

L325: Methodological

L379: is also

L444: see comment L191

L459: convert mile to km for consistency

L481: those truck drivers who reported

L482: did not change risky

L493: are the most

L536: explain term ‘at-grade’

L659: Their model – who are they?

L698: that despite

L702: How does identification inside vehicle prevent collisions?

L731: ‘herps’ is slang

 

 

Comments on the Quality of English Language

See above

Author Response

Reviewer#3 comments and answers

Comment: The authors present a comprehensive review of roadkill research from published analyses in the 1930s from North America to a contemporary view of the last few decades. The review is based on a literature search which is well-illustrated in Figure 1 but a bit muddled in the text. The sample is biassed to Europe and USA and somewhat thin from other regions (e.g. few references to Oceania relative to effort). The tendency is to use a few exemplars from other regions (e.g. Brazil, East Asia) as case-studies to support or round-out the generalizations presented. The literature is summarised under several headings (some with sub-headings) that include impact on wildlife, wildlife behaviour, patterns and determinants, human dimensions, and mitigation. These provide an excellent overview not withstanding the bias in the fauna. In some instances, the examples tend to stray off topic. The discussion likewise is under several headings with an appropriate focus on gaps and future directions to arrive at interesting and pertinent conclusions.

Answer: Thank you

Comment: The writing is a bit erratic with some sections peppered with grammatical errors, especially missing articles. One omission is to present common names only for all fauna species. The species binomial in italics should be included either with the first mention in the text or alternatively the authors could provide an appendix of all common and species names.

Answer: thank you for proposed solution of the problem we experienced while writing first version of the paper. As zoologists, we use species binomial in italics with the first mention, but this is obscuring readability of non-zoological text. Therefore, we are happy to provide the list of species as
Appendix A.1. List of species in the text, presented in the order of their first appearance.

Comment: In the following, I suggest some revisions for minor errors.

Answer: thank you very much for your time, all proposed changes were accepted.

L37: in the 1990s
Answer: corrected as proposed

L61: using a systematic
Answer: corrected as proposed

L63: defined the scope…to include
Answer: corrected as proposed

L66-7: a discussion of research gaps…ecology.
Answer: corrected as proposed

L67-8: The timeframe for the analyzed sources is the last…with a limited
Answer: corrected as proposed

L68-9: The taxonomic…and the geographical
Answer: corrected as proposed

L70: Papers were
Answer: corrected

L71: including a limited
Answer: corrected as proposed

L72: mainly “roadkill”
Answer: corrected as proposed

L75: Explain other?
Answer: deleted

L76: In looking
Answer: corrected as “When looking…”

L78: hundreds of records…Scholar alone
Answer: corrected as “As these searches yielded thousands of records in Google Scholar alone,”

L81: Therefore, most
Answer: corrected as proposed

L85: an AI-based
Answer: corrected as proposed

L86: check if
Answer: comma removed

L88: After a draft
Answer: corrected as proposed

L89: the number of
Answer: corrected as proposed

L90: of the grey
Answer: corrected as proposed

L91: and finally papers
Answer: corrected as proposed, thank you

L104: roads expands
Answer: corrected as “As highways and roads continue to expand”

L107: the last two
Answer: corrected

L112: A multi-country
Answer: corrected

L144: in the Czech
Answer: corrected

L148: results contrast
Answer: corrected

L161: the largest
Answer: corrected

L165: a negligible
Answer: corrected

L168: increasing the
Answer: corrected

L182: and reduction
Answer: corrected

L185: as the population
Answer: corrected

L191: Inconsistent attribution of state to country which is USA, check other state references
Answer: thank you for noticing, changed where “US” was used

L227: Seems off-topic why is it similar?
Answer: edited as “Another large-scale study in Brazil found that endangered mammals are also affected by vehicle collisions [98].”

L226: intensity is exceeded…became impermeable
Answer: this was Line 266 – then changed as requested

L287: Off-topic?
Answer: sentence deleted

L317, 321: species names in italics
Answer: corrected

L325: Methodological
Answer: corrected

L379: is also
Answer: corrected

L444: see comment L191
Answer: all changed to USA

L459: convert mile to km for consistency
Answer: then it will be “In Washington State, wildlife crossing structures are estimated to prevent approximately 0.6 to 1.9 collisions per kilometer”

L481: those truck drivers who reported and L482: did not change risky
Answer: corrected as proposed, thank you

L493: are the most
Answer: corrected

L536: explain term ‘at-grade’
Answer: An at-grade fauna passage is a type of wildlife crossing that allows animals to cross a road at the same level as vehicle traffic—essentially, it’s an opening or gap in fencing where wildlife can cross directly over the road surface. These are much less expensive to build than overpasses or underpasses and are typically used on smaller or intermediate-sized roads with lower traffic volumes. We changed text as “Similarly, Scandinavian research found no significant difference in crossing probability among wild boar, roe deer, and fallow deer between at-grade fauna passages (openings or gap in fencing where wildlife can cross directly over the road surface) and wildlife-specific structures, suggesting that cost-effective at-grade options may help mitigate barriers along fenced roads [222].”

L659: Their model – who are they?
Answer: they are Cunningham and coauthors, mentioned in previous sentence. We did requested change.

L698: that despite
Answer: mistype corrected

L702: How does identification inside vehicle prevent collisions?
Answer: thank you, we made mistake while editing, it was to mention that smart system is inside the vehicle: “For example, H. Guo et al. [287] introduce a Wi‑Fi‑based detection system installed inside vehicles that swiftly identifies humans and animals and thus prevent collisions.”

L731: ‘herps’ is slang
Answer: agree, apologies. Authors mention snakes, change done.

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for addressing my suggestions to improve your manuscript - well done!