title: Experimental study designs to improve the evaluation of road mitigation measures for wildlife.
abstract: An experimental approach to road mitigation that maximizes inferential power is essential to ensure that mitigation is both ecologically-effective and cost-effective. Here, we set out the need for and standards of using an experimental approach to road mitigation, in order to improve knowledge of the influence of mitigation measures on wildlife populations. We point out two key areas that need to be considered when conducting mitigation experiments. First, researchers need to get involved at the earliest stage of the road or mitigation project to ensure the necessary planning and funds are available for conducting a high quality experiment. Second, experimentation will generate new knowledge about the parameters that influence mitigation effectiveness, which ultimately allows better prediction for future road mitigation projects. We identify seven key questions about mitigation structures (i.e., wildlife crossing structures and fencing) that remain largely or entirely unanswered at the population-level: (1) Does a given crossing structure work? What type and size of crossing structures should we use? (2) How many crossing structures should we build? (3) Is it more effective to install a small number of large-sized crossing structures or a large number of small-sized crossing structures? (4) How much barrier fencing is needed for a given length of road? (5) Do we need funnel fencing to lead animals to crossing structures, and how long does such fencing have to be? (6) How should we manage/manipulate the environment in the area around the crossing structures and fencing? (7) Where should we place crossing structures and barrier fencing? We provide experimental approaches to answering each of them using example Before-After-Control-Impact (BACI) study designs for two stages in the road/mitigation project where researchers may become involved: (1) at the beginning of a road/mitigation project, and (2) after the mitigation has been constructed; highlighting real case studies when available.
authors.affiliation: Geomatics and Landscape Ecology Research Laboratory, Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6. Electronic address: trytwinski@hotmail.com.
authors.forename: Trina
authors.initials: T
authors.lastname: Rytwinski
authors.affiliation: Australian Research Centre for Urban Ecology, Royal Botanic Gardens Melbourne, C/-School of Botany, University of Melbourne, 3010 Victoria, Australia.
authors.forename: Rodney
authors.initials: R
authors.lastname: van der Ree
authors.affiliation: Geomatics and Landscape Ecology Research Laboratory, Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
authors.forename: Glenn M
authors.initials: GM
authors.lastname: Cunnington
authors.affiliation: Geomatics and Landscape Ecology Research Laboratory, Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
authors.forename: Lenore
authors.initials: L
authors.lastname: Fahrig
authors.affiliation: Institute of the Environment & Ottawa-Carleton Institute of Biology, 555 King Edward, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: C Scott
authors.initials: CS
authors.lastname: Findlay
authors.affiliation: Department of Biology, University of New Brunswick at Saint John, Saint John, 550, New Brunswick, Canada E2L 4L5.
authors.forename: Jeff
authors.initials: J
authors.lastname: Houlahan
authors.affiliation: Department of Geography, Planning and Environment, Concordia University Montreal, 1455 de Maisonneuve Blvd. W Suite H1255, Montreal, Quebec, Canada H3G 1M8.
authors.forename: Jochen A G
authors.initials: JA
authors.lastname: Jaeger
authors.affiliation: Australian Research Centre for Urban Ecology, Royal Botanic Gardens Melbourne, C/-School of Botany, University of Melbourne, 3010 Victoria, Australia.
authors.forename: Kylie
authors.initials: K
authors.lastname: Soanes
authors.affiliation: Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
authors.forename: Edgar A
authors.initials: EA
authors.lastname: van der Grift
mesh_terms: D063147:Animal Distribution; D000818:Animals; D000835:Animals, Wild; D003247:Conservation of Natural Resources; D004779:Environment Design
keywords: Before-after-control-impact; Effectiveness; Experimental design; Population persistence; Road impacts; Road planning