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15 CHAPTER 2 Phase 1 Summary 2.1 Literature Search and Database nearest pond to lay eggs, there is a continuous theme of daily and seasonal movement throughout the entire life cycle of all The research team searched the literature and spoke with faunal species. With the increased placement of road through knowledgeable professionals in an effort to gather into a data- the natural landscape, obstacles are created to both short- and base all publications related to the ecological effects of roads, long-distance movements in both aquatic and terrestrial wildlife mitigation measures, and AVCs in North America that species. To better accommodate species' needs to move freely, were published after 1999. Select older as well as international mitigation measures need to be brought into transportation papers were included in the database. All papers were linked programs and project plans at the inception of long-range with key words. The majority of entries have been read by team plans, and considered in the daily maintenance of roads and members; most have annotated descriptions of the research. railways. In North America, mitigation measures have been These entries have been linked to the search engine of the com- installed for wildlife along roads since approximately 1970. In panion website, The more than 370 the interim, crossings have been designed, built, monitored, entries are accessible through keyword searches and if the full and studied. While much has been learned, there is a need to paper is available on another website, a hyperlink will connect collect, organize, and better communicate current knowledge the user to that paper. in order to learn from failures and build on successes. One major theme in effective mitigation measures and in 2.2 The State of the Practice current scientific thinking of transportation corridors and and Science of Wildlife wildlife is the need for restoring permeability. As more is Crossings in North America learned about movement needs of different species in differ- ent ecosystems, it is becoming evident that efforts that help Introduction one or two focal species move under and over roads may not How well are the effects of roads being mitigated for adequately compensate for the lack of permeability that roads wildlife? Improvements in the science and practice of trans- and railways cause for the larger suite of species in an ecosys- portation (road) ecology have increased dramatically over the tem. Permeability is a guiding principle to consider in efforts past decade, yet overall only a small amount is known of what to accommodate wildlife in transportation corridors. Achiev- has been accomplished or how these efforts are helping to ing permeability begins when several different types of miti- make the roaded landscape more permeable for wildlife. In gation measures, e.g., different types and sizes of crossings, this chapter, the concept of permeability, the overall efforts are placed throughout the course of the transportation corri- and trends in North America to mitigate roads for wildlife dor so that most species and many individuals of nearby with wildlife passages, and trends and future needs in the prac- populations are able to use these crossings. These crossings tice and science of mitigating roads for wildlife are explained. would be placed in sufficient quantity so that most species, in Wildlife need to move to meet their basic requirements, and both day-to-day and specific seasonal movements, would be there is an imperative to evaluate current mitigation efforts able to find and use crossings within a single home range. The along transportation corridors to facilitate species in meeting intent of this research is to document North American efforts these needs. Whether looking at phenomena such as long- to mitigate the roaded landscape for wildlife movement; this distance caribou migrations, butterfly movements, fish re- report highlight projects where multiple passages appear turning to inland waters to spawn, or frogs trying to reach the successful in achieving permeability for wildlife.