GIS and Wildlife Habitat Connectivity

Introduction

Wildlife corridors are sections of land that allow wild animals to move between the habitat that they utilize. These wildlife habitat connectivity corridors are vitally important in today’s world that is vastly dominated by humans and human development. Much of the habitat that many species use is fragmented, and it no longer allows for individuals to move around on the landscape. This prevents dispersal and growth of populations, it prevents gene flows and creates genetically poor populations, and it prevents many populations access to further resources. Most importantly, with the increasingly intense effects of climate change, it prevents many animals from moving to find more suitable habitat as the climate of the earth changes.

Wildlife road crossings are an important planning and mitigation tool for the Department of Transportation. They have increasingly utilized corridors and crossings to save money and prevent accidents when building and maintain our vast road system. Therefore, there is lots of research being done on best management practices for connecting wildlife habitat. The goal is to conserve areas that facilitate movement, and restore connectivity in areas that impede movement.  

Designing and planning wildlife movement corridors goes hand in hand with geographic information systems. GI systems help conservationists plan the best possible corridor systems by allowing planners to visualize and test alternatives for highest probability movement of species.

Annotated Bibiliography

Beckman, J.P., Clevenger, A.P., Huijser, M.P., Hilty, J.A. Safe Passages: Highways, Wildlife, & Habitat Connectivity. Island Press, 2010.

This book discusses the importance of scale in wildlife corridor & crossing planning. In general, it is more helpful to look at large scale, possibly state wide when planning. It’s the difference between project and system level approaches. You want to look at the big picture, it will save money in the long run, and it will make the habitat system better overall and in the long term and prevents the need for redesigns of systems later. It emphasizes the importance and need for good data to achieve these system level planning goals.

Beier, P. 2013. Corridor Design. http://corridordesign.org/

This website is an informative website about how to actually implement corridor and wildlife habitat connectivity design. The creators of the website have created an ArcGIS Toolbox to aid in creating and designing wildlife corridors. The creators are all experts in the field of wildlife & road ecology and felt the duty to share their knowledge with the general public. They wanted to share “conceptual steps and specific GIS methods” that had not been previously documented adequately. Their tools and insight offered on this website are designed with a large scale real-world heterogeneous landscape. The website also has many links to further information and research.

Beier, P., Majka, D.R., Newell, S.L. 2009. Uncertainty of Least-Cost Modeling for Designing Wildlife Linkages. Ecological Applications. 19(8). 836-851.

Least-Cost Corridor models look at a raster grid of resistance from many different factors that an animal will encounter when trying to move across a landscape. These factors include things such as road density, habitat type or canopy cover. These least-cost corridor models are often used when planning restoration or habitat connectivity projects. There is often uncertainty in these models when it comes to the weights assigned to resistance factors and the values assigned to each class in a feature. These values are usually interpreted from literature on habitat, but can range widely from model to model. There is also uncertainty in what focal species you utilize to target the design and placement of your corridor design. The study look at many different models as they pertained to a habitat linkage project in Southern California. They determined that there is a need to include and uncertainty analysis in the design of connectivity systems and other conservation models in order to evaluate the outcomes. They mentioned that uncertainty analysis is not currently often used in conservation planning, but is common in population abundance models, and that it should be an important factor in conservation planning, such as habitat linkage projects.

Beier, P., Majka, D.R., Spencer, W.D. 2007. Forks in the Road: Choices in Procedures for Designing Wildland Linkages. Conservation Biology. 22(4). 836-851.

What are your options when beginning the planning and design process of a wildlife corridor. This article discusses Many different geographic information systems processes you can utilize to accomplish your connectivity goals. It gives specifics on what different choices there are, and in what situation those processes would be the most useful and powerful. The processes are reviewed for multiple different focal species and for “umbrella” species, or a single species that is a generalist, and therefor it’s management strategies encompass many other species. Analysis area definition, focal species identification, what the model should include, factor metrics, how resistance is estimated, corridor width, and how to accommodate climate change in the design are all discussed in great depth.

Clevenger, A., Huijser, M., United States Department of transportation, Federal Highway Administration, Western Transportation Institute. Wildlife Crossing Structure Handbook: Design and Evaluation in North America. March 2011.

This is a manual for managers looking to design and plan wildlife crossing and habitat connectivity when it pertains to roads. It goes into depth about the field of road ecology. The field of road ecology relies heavily on geographic information systems to predict wildlife movement, the potential for habitat fragmentation by roads, and to identify where the ideal place for wildlife crossings would be. Geographic information systems are able to “facilitate the identification of wildlife habitat linkages and movement corridors.” (page 27). There is also a benefit of using a GIS with a combination of road network, traffic data, road kill data, and other useful data sets (such as looking at the compatibility of adjacent land use to the goals of the project). Combining multiple resources provides greater accuracy in identifying habitat linkages. The manual discusses the need for system-level large scale analysis to create a formal broad scale plan for wildlife connectivity.

Forman, R.T., Sperling, D., et al. Federal Highway administration, California Department of Transportation, The Nature Conservancy. Road Ecology: Science & Solutions. Island Press, 2003

This book is mostly a review of crossing structure types, and where they will be most effective depending on what habitat type you have and what species of animal is most abundant. It is also a review of mitigation strategies when beginning a new road project. The large takeaway from this book is the use of geographic information systems and models in analyzing current crossing structures, and determining where they are most effective. It’s really using a GIS as a tool to identify what is working and what is not in the field of wildlife road ecology.

Knopff, A.A., Knopff, K.H., Boyce, M.S., St Clair, C.C. 2014. Flexible Habitat Selection by Cougars in Response to Anthropogenic Development. Biological Conservation. 178. 136-145.

This was a study conducted to determine large predators, specifically cougars, ability & willingness to utilize a changing and human dominated landscape. The researchers heavily utilized a geographic information system to complete their analysis. They utilized a gradient of habitat “ruggedness” and cougar movements within that gradient to determine their ability to adapt to human presence. Anthropogenic disturbance was calculated for each pixel using a combination of buildings, roads, pipeline, well-density, & seismic lines. They found that the cougars in their study were “capable of adjusting their behavior to accommodate anthropogenic development” (pg 142). There was a difference between cougars that were identified as more rural and cougars that were more urban. The rural cougars would generally avoid anthropogenic changes more often than the urban cougars who may be more used to human development.

Loro, M., Ortega, E., Arce, R.M., Geneletti, D. 2015. Ecological Connectivity Analysis to Reduce Barrier Effects of Roads. An innovative Graph-Theory approach to Define Wildlife Corridors with Multiple Paths and Without Bottlenecks. Landscape and Urban Planning. 139. 149-162

This study was conducted to determine ideal locations for wildlife habitat movement corridors among a new highway development project. A geographic model was developed, and the landscape was simplified as nodes (habitat patches) and lines or links (wildlife movement corridors). The geographic information system model was developed to take a network level approach in order to look at all possible corridor options and their alternatives. Alternatives were developed based on habitat patch size, bottleneck potential, and cost. The researchers were evaluating paths for habitat patches to preserve connectivity and benefit both wildlife and humans.

McRae, B.H., Hall, S.A., Beier, P., Theobald, D.M. 2012. Where to Restore Ecological Connectivity? Detecting Barriers and Quantifying Restoration Benefits. PLoS ONE. 7(12).

There has been little effort to identify restoration opportunities by mapping barriers. Most movement corridor conservation efforts have been focused on acquiring new habitat for animals to inhabit. This study made the point that it is crucial to focus on movement barriers that are restorable, a triage of the landscape, fix what is able to be fixed in order to restore what we can in a very human dominated landscape. There are tradeoffs between restoring existing habitat and acquiring new land. These researchers used GIS mapping to identify areas that currently reduce connectivity between locations the most, these are areas that if restored would greatly increase movement on the landscape. Detecting barriers can increase conservation options available and result in more robust conservation plans. Looking at more than just the habitat patches can improve the movement system, save time, and save money.

Milanesi, P., Holderegger, R., Caniglia, R., Fbbri, E., Randi, E. 2015. Different Habitat Suitability Models Yield Differnent Least-Cost Path Distances for landscape Genetic Analysis. Basic and Applied Ecology. 17(2016). 61-71.

A habitat suitability model, or a species distribution model, associates locations of animals with many ecological variables in an analysis. They also give a probalistic identification of least-cost path distances within the field of landscape genetics. This study evaluated many different habitat suitability models that are often used in analysis. Specifically, the evaluated the accuracy of the models to predict the least-cost path distances across the landscape. The used a long-term monitoring program data on wolves in the Italian Apennines and western Alps, and were able to look at 923 individual wolves. This genetic data was used as the input data set to analyze each model and its outcomes. The study showed significant differences between models when it came to the least-cost distances, they suggest that these differences would be accentuated in further landscape genetic analysis.

Perkl, R.M. 2016. Geodesigning Landscape Linkages: Coupling GIS with Wildlife Corridor Design in Conservation Planning. Landscape and Urban Planning. 156. 44-58.

A model called the Automated Design Model (ADM) was designed with the intention of addressing the design of wildlife corridor interior. There is much research on how to select and implement wildlife connectivity corridors, but a lack of information on how to actually manage for the habitat in those corridors. This model gives detailed vegetation planting designs for the interiors of the corridors. This model is meant to be combined with a corridor design and delineation model. It helps to plan how a manager can manage the vegetation of their corridor so that the health of the habitat will persist into the future.

Richard, Y., Armstrong, D.P. 2010. Cost Distance Modelling of Landscape Connectivity and Gap-Crossing Ability Using Radio-Tracking Data. Journal of Applied Ecology. 47(3). 603-610.

The degree that a landscape allows movement between habitat patches is known as landscape connectivity. The goal of this study was to design a model that incorporated a cost-distance model, and step-selection functions, and show that cost distance modeling can incorporate animal’s ability to cross habitat gaps and not just move only through habitat. They wanted to test for the influence of various landscape features on movements of individual species. The study was interested in looking at structural connectivity, the physical spatial structure of landscapes, and functional connectivity, how the landscape actually influences movement on the ground. The study asked, “Given the fact that an individual moved a certain distance, what factors, if any, led this individual to choose the observed destination compared with other available alternatives of similar distance?”

Roger, E., Laffan, S.W., Ramp, D. 2011. Road Impacts a Tipping Point for Wildlife Populations in Threatened Landscapes. Population Ecology. 53(1). 215-227.

This study analyzed how much roads and other human development may affect wildlife populations from persisting into the future. Common Wombats in New South Wales, Australia in Kosciuszko National Park were analyzed. This species was chosen for its relative abundance and high roadside fatalities. The study created a “stage-structured and spatially explicit” GIS model to look at how different factors impacted the wombat population into the future. They focused on what would be the most effective factor to implement a mitigation technique to ensure continued population survival into the future. They found that mitigating road-kill was the most effective method for continued success of the wombat population, suggesting that structures such as wildlife undercrossings and overcrossings are a vitally important mitigation strategy.

Spens, J., Englund, G., Lundqvist, H. 2007. Network Connectivity and Dispersal Barriers: Using Geographic Information System (GIS) Tools to Predict Landscape Scale Distribution of a Key Predator (Esox Lucius) Among Lakes. Journal of Applied Ecology. 44(6). 1127-1137.

This study aimed to create a model that would accurately predict distribution by taking into account dispersal barriers and not just habitat requirements. The used Norther Pike (Esox Lucius) in lakes in the northern region of Sweden. The Northern Pike had previously been eradicated from many lakes, they were reintroduced in both upstream and downstream lakes during the study to determine their dispersal patterns. The model that they developed took at whole watershed approach in order to create a “whole drainage network distribution.”  They created their model using maximum stream slope as the potential for distribution barrier. The study found that connectivity is more important than habitat characteristics in determining species distribution and dispersal in a model. They hope for others to use their model to create a more accurate predictor of how reintroduced native fish will disperse back to their original ranges.

White, P., Defenders of Wildlife. Getting up to Speed: A Conservationists Guide to Wildlife & Highways. 2007.

This book on road ecology focuses on how to plan these types of large scale habitat connectivity projects. In one chapter, it emphasizes the types of data sets that are needed to help create a plan that will work effectively for both the wildlife and the humans. Aerial photos, land ownership, topographic maps, roadkill information, vegetation maps, wildlife habitat & range information, and wildlife behavior & movement patterns. This source is more of a broad overview of wildlife and highway problems and planning.

"Conservation is a state of harmony between men and land."

–Aldo Leopold