Establishing wildlife corridors is a key conservation tool in many landscapes
Written by Annika Keeley & Jamie Faselt
July 15th 2025
Photo credit: NPS photo
Maintaining or re-establishing ecological connectivity is increasingly recognized as crucial for conserving biodiversity. Models of ecological connectivity are commonly used to predict how well different areas in the landscape allow animals to move between them. Corridor models specifically identify pathways where animals are most likely to travel between, for example, protected areas (Figure 1).
The authors of a recent paper (Iverson et al. 2024) suggest that improving landscape management and stewardship to ensure the permeability of a landscape to wildlife movement is a better approach to achieving conservation outcomes than protecting wildlife corridors between protected areas. In our comment paper, we argue that the optimal approach depends on the landscape context, conservation goals, and the species involved and suggest that corridor plans help prioritize specific places for protection, improved management, wildlife crossings, and additional monitoring. Discounting the importance of corridor plans could have grave consequences for connectivity conservation. We urge project planners not to mistakenly question the validity of corridor plans based on the results of a single study.
Figure 1. Output of a corridor model: Santa Monica-Sierra Madre Linkage in southern California (from Penrod et al. 2006). This corridor model is the union of least-cost corridors for mountain lions, mule deer, and badgers. It has informed land use plans, land acquisition, and management actions. Despite being in the vicinity of the Los Angeles Metropolitan Area the corridor is still a functional connection between the protected areas on either end.
Validating corridor models is important
We do agree with Iverson et al. (2024) on the importance of testing the assumptions and predictions of corridor models and applaud them for striving to assess the validity of modelled corridors identified in several state-wide and regional connectivity planning efforts in California. However, while the authors conclude that their results challenge the use of corridor models for species connectivity and related conservation decisions, we believe their findings actually support the effectiveness of corridor models for species sensitive to human changes. We explain that the reason may be the misalignment of the validation assumptions with model objectives.
Best practices for model validation studies
We offer our perspective on best practices for conducting validation studies, which include the following points.
1. Only single models, or multiple models with the same connectivity objectives, should be subject to validation because the validation metric must be tied to the original study objective.
2. Validation data sets need to match the objectives of the corridor model being used.
3. Data used to model corridors should be independent from the data used to validate the outputs.
4. The resolution at which validation data were collected needs to match the resolution of the corridor models.
5. When using wildlife-vehicle collision data for validation, accounting for factors such as traffic volume, human observation biases, species natural histories, and the terrain, is important.
6. Stratifying the study area is a recommended approach to evaluate whether corridor models do a better job in differently impacted landscapes.
Conclusion
Mapping and protecting corridors is critical to conserving wildlife, as is maintaining or increasing permeability to support landscape connectivity. Discounting the importance of corridor models is not warranted at this time and could hinder the development and implementation of landscape conservation plans. Further validation studies of corridor models in general are needed, and we would like to see new programs and funding aimed at collecting data to further improve them. Validating corridor models requires that researchers carefully consider model objectives, scale, and potential bias in data.
Author information
Annika Keeley, Center for Large Landscape Conservation (annika@largelandscapes.org). Annika is a conservation biologist specializing in connectivity science. She advises on connectivity projects and programs across the globe.
Jamie Faselt, Center for Large Landscape Conservation (jamie@largelandscapes.org). Jamie is a conservation science specialist. She provides technical support for connectivity conservation projects both in the United States and internationally.
Source citation
Keeley, A. T. H., Beier, P., Belote, R. T., Clark, M., Clevenger, A. P., Creech, T. G., ... & Zeller, K. A. (2025). Comment on Functional landscape connectivity for a select few: Linkages do not consistently predict wildlife movement or occupancy. Autum R. Iverson, David Waetjen, Fraser Shilling. Landscape and Urban Planning, 253, 105217.
Penrod, K., C. Cabañero, P. Beier, C. Luke, W. Spencer, E. Rubin, R. Sauvajot, S. Riley, and D. Kamradt. 2006. South Coast Missing Linkages Project: A Linkage Design for the Santa Monica-Sierra Madre Connection. Produced by South Coast Wildlands, Idyllwild, CA. www.scwildlands.org, in cooperation with National Park Service, Santa Monica Mountains Conservancy, California State Parks, and The Nature Conservancy.
Editor:
Julia Kintsch
Cite this summary:
Keeley, A. & Penrod, K. (2025). Establishing wildlife corridors is a key conservation tool in many landscapes. Edited by Kintsch, J. TransportEcology.info, Accessed at: https://transportecology.info/research/corridor-validation-best-practices